vol. 50 no. 3 summer 2016 colorado birds vol 50... · 2016. 8. 17. · colorado birds summer 2016...

Vol. 50 No. 3 Summer 2016

The Colorado Field Ornithologists’ Quarterly

Colorado Birds

Perch Deterrent to Save RaptorsThe Hungry Bird—Breakfast at Jane'sYellow-rumped Warbler ID

Colorado Field OrnithologistsPO Box 929, Indian Hills, Colorado 80454

cfobirds.org

Colorado Birds (USPS 0446-190) (ISSN 1094-0030) is published quarterly by the Col-orado Field Ornithologists, P.O. Box 929, Indian Hills, CO 80454. Subscriptions are obtained through annual membership dues. Nonprofit postage paid at Louisville, CO. POSTMASTER: Send address changes to Colorado Birds, P.O. Box 929, Indian Hills, CO 80454.

Officers and Directors of Colorado Field Ornithologists: Dates indicate end of cur-rent term. An asterisk indicates eligibility for re-election. Terms expire at the annual convention. Officers: President: Doug Faulkner, Arvada, 2017*, [email protected]; Vice Presi-dent: David Gillilan, Littleton, 2017*, [email protected]; Secretary: Chris Owens, Longmont, 2017*, [email protected]; Treasurer: Michael Kiessig, Indian Hills, 2017*, [email protected]

Directors: Christy Carello, Golden, 2019; Amber Carver, Littleton, 2018*; Lisa Ed-wards, Palmer Lake, 2017; Ted Floyd, Lafayette, 2017; Gloria Nikolai, Colorado Springs, 2018*; Christian Nunes, Longmont, 2019

Colorado Bird Records Committee: Dates indicate end of current term. An asterisk indicates eligibility to serve another term. Terms expire 12/31.

Chair: Mark Peterson, Colorado Springs, 2018*, [email protected]

Committee Members: John Drummond, Colorado Springs, 2016; Peter Gent, Boul-der, 2017*; Tony Leukering, Largo, Florida, 2018; Dan Maynard, Denver, 2017*; Bill Schmoker, Longmont, 2016; Kathy Mihm Dunning, Denver, 2018*

Past Committee Member: Bill Maynard Colorado Birds Quarterly:

Editor: Scott W. Gillihan, [email protected]

Staff: Christy Carello, science editor, [email protected]; Debbie Marshall, design and layout, [email protected]

Annual Membership Dues (renewable quarterly): General $25; Youth (under 18) $12; Institution $30. Membership dues entitle members to a subscription to Colorado Birds, which is published quarterly. Back issues/extra copies may be ordered for $7.50. Send requests for extra copies/back issues, change of address and membership renewals to [email protected]. Contributions are tax deductible to the extent allowed by law.

COPYRIGHT © 2016 by Colorado Field Ornithologists. Reproduction of articles is permitted only under consent from the publisher. Works by U.S. and Canadian governments are not copyrighted.

The Colorado Field Ornithologists’ Quarterly Vol. 50 No. 3 Summer 2016

PRESIDENT’S MESSAGE ....................................... 126Doug Faulkner

CFO BOARD MEETING MINUTES ......................... 128Larry Modesitt

ABSTRACTS FROM PAPERSSESSION IN lAMAR ............................................. 132Christy Carello

ROBERT S. WIllIAMSON ..................................... 138Bob Righter

THE HUNGRY BIRD ............................................. 141Dave Leatherman

NEWS FROM THE FIElD:WINTER 2015–2016 ............................................. 147David Dowell

CFO SAGEBRUSH SPARROW FIElD TRIPS .......... 157Mike Henwood

IN THE SCOPE ...................................................... 158Tony Leukering

SUCCESSFUl USE OF A PERCH DETERRENT ...... 166James F. Dwyer et al.

ON THE IMPORTANCE OF FOOTHIllSSHRUBlANDS ...................................................... 175Jameson F. Chace et al.

Lazuli Bunting, Fort Collins, Lar-imer County, 19 December 2015 Photo by Rachel Hopper

126 Colorado Birds Summer 2016 Vol. 50 No. 3

PRESIDENT’S MESSAGE

Doug Faulkner

The 52nd annual convention of the Colorado Field Ornithologists in Lamar was well attended with a record number of participants just shy of 230. For the past several years, each consecutive convention has set the record for number of participants. There was a time (say, 2013) when 160 participants was considered remarkable. We have

now had two consecutive conven-tions with over 200 participants. Conventions of that size present a unique set of challenges, but par-ticularly with finding facilities that can accommodate so many for the banquet and papers session. Fortu-nately, next year’s convention will be in Steamboat Springs—a town tailor-made for hosting large events.

The birding theme at the Lamar convention was quality over quan-tity. The level of activity, even for local breeders, was much lower than expected for that time of year. I sup-pose the upside to lower numbers of birds is that we had the opportunity to watch and study the ones we saw. Instead of flicking our binoculars frantically from bird to bird like a hummingbird flitting from flower to flower, field trip leaders could focus everyone’s attention to a particular bird. I think most of all those who saw lifers at the convention can ap-preciate the opportunity to study a

single bird for longer than a 3-year-old’s attention span. (For the re-cord, birding a major fall-out is a serious adrenaline rush and should be on everyone’s bucket list).

The highlights, however, did not disappoint. There could not have been a better start than having a Golden-winged Warbler at the Stulp’s Ranch. Unfortunately, that was one I missed by 20 minutes on a windy late afternoon. Ah well, such is birding. As expected for early spring migration, new species were discovered on a daily basis and each field trip had an opportunity to find this year’s newest arrivals.

Next year’s convention will be a very different flavor. We will be traveling to northern Colorado’s mountains in early summer. Vi-sions of Pine Grosbeak, Three-toed Woodpecker, and even Sandhill

Colorado Birds Summer 2016 Vol. 50 No. 3 127

Crane are already dancing in my head. Steamboat Springs also of-fers an opportunity to visit some relatively lower-elevation sites like the Walden area reservoirs. For state listers, Wyoming is tantalizingly close enough to merit a trip for Purple Martin and Flammulated Owl, where the only place to regularly find those species is in the Medicine Bow Mountains just across the state line. County listers should be able to round out their breeding bird species for Routt County during the convention (check out CFO’s County Birding webpage). For the rest of us, just enjoying whatever birds we see with our friends will be worth the trip to Steamboat by itself.

Similar to Lamar, I hope to sprinkle in a couple of trips that don’t focus only on birding. Early summer will be a good time for some butterfly, dragonfly, and botany explorations. Sorry, you will have to enjoy the local hot springs on your own time. Somehow, binoculars and bathing suits don’t go well together. Which reminds me, Steam-boat Springs will have plenty of activities for your non-birding com-panions so bring them along as well. While you are out taking in the natural scene, they can be touring the city and taking in the cultural scene.

Look for more convention details on the CFO website as we ramp up the planning process in earnest and start nailing down details later this year. If you have any interest in helping to organize or want to volunteer at next year’s convention, please reach out to me. I hope to see you there!

Photo Editor NeededAfter serving faithfully as this journal’s photo editor for five years,

Christian Nunes has stepped down. We have big shoes to fill, but fill them we must. If you are knowledgeable about Colorado’s birds, have experience with digital photos (including the skills and software to do basic editing: cropping, resizing, etc.), and have a few hours to spare for each quarterly issue, please consider volunteering as the Colorado Birds Photo Editor. If you are interested, please contact Scott Gillihan, Editor ([email protected]).


CFO BOARD MEETING MINUTES

9 April 2016Comfort Inn, Fruita, ColoradoLarry Modesitt

President Doug Faulkner called the April quarterly meeting to order at 11:06 a.m. after pre-meeting outings featuring Sagebrush Sparrows in both Colorado and Utah, a Long-billed Curlew, and the easiest-ever viewing of a Western Screech-Owl. Other Officers pres-ent were Vice President David Gillilan, Secretary Larry Modesitt, and Treasurer Michael Kiessig. Directors Christy Carello, Lisa Ed-wards, Ted Floyd, Mike Henwood, Bill Kaempfer, Christian Nunes, Chris Owens, and Mark Peterson also were present. Scott Gillihan sent his regrets.

Although we politely declined to dine at Mike Henwood’s recom-mended Feedlot Restaurant, Doug thanked Mike for arranging both the meeting and birding events in Fruita (near Grand Junction). Truth be told, all work and no play makes Directors a dull lot.

Secretary’s Report: Larry Mode-sitt’s minutes of the 23 January 2016 board meeting did not reflect correc-tions submitted, and were approved with the proviso of corrections on our website.

Treasurer’s Report: The board reviewed Michael Kiessig’s previously submitted budget. We are spending more on grants than normally, but we are well funded, especially with a high registration for this year’s convention. One of our ongoing requirements for fiscal responsibility is for bank state-ments to be sent, not only to the Trea-surer, but also to another board mem-ber. Lisa Edwards has been doing this review, and it now will transition to Chris Owens.

2016 Lamar Convention Plan-ning Roles and Responsibilities—Doug Faulkner

1. Registration: David Gillilan reported a record number of registra-tions, 224. Eclipsing the prior year’s total convention attendance is begin-ning to be the norm.

2. Field Trips: Doug reported that all day trips are fully planned, plotted, and staffed. Nocturnal trips, however, still require last-minute adjustments to be made when exact conditions, such as impassable conditions from high water, can be determined. There still are openings in field trips for late registrants. Ted Floyd will be sending instructions to leaders, plus a template for leaders to be sent to participants.

3 David Gillilan pointed out that 175 people are expected at the picnic. In case of rain, a backup pic-nic site will be available. Ted Floyd has notified local officials, and Lamar Mayor Roger Stagner will be welcom-ing us. David and Lisa will make an-other pre-convention trip to ensure that all arrangements for facilities and backups are properly organized.


We greatly appreciate that some local Lamar residents have donated $2,000 anonymously for the picnic.

4. Food arrangements: David Gil-lilan suggested, based upon the large quantity of banquet vegetarian din-ners ordered, ordering more veggie burgers for the picnic.

5. Papers session: Christy Carello reported that nine abstracts have been accepted. This means that each pre-sentation will be 15 minutes long.

6. Youth/Student Mixer: Christy and Ted will notify students about the mixer, which is free to students.

7. Exhibitors: Larry Modesitt an-nounced that exhibitors will be Birder’s Digest (Jeff Jones), Bird Conservancy of the Rockies, Denver Field Ornithol-ogists, Environment for the Americas (sponsor of International Migratory Bird Day), Front Range Birding (bin-oculars and spotting scopes), Sherrie York original art (Sherrie illustrated last year’s convention T-shirt Tree Swallows), and St Vrain Jam (diabet-ic- and picnic-friendly jams).

8. Christian Nunes has pur-chased new Jeopbirdy software. He announced, “It will work!”

9. Audio-Visual: As always, hav-ing compatible A/V equipment is a priority. We made arrangements to ac-quire and verify usage of all equipment for Jeopbirdy, paper sessions, and the banquet.

10. T-shirts: Lisa Edwards an-nounced she will approve the first run of T-shirts next week.

11. Awards: Chris Owens and Lisa Edwards announced that plaques have been ordered and recipients notified for them to attend the banquet.

12. Volunteer assistance: Chris Owens has received help from a large number of volunteers who will help with various functions, including “Ask Me.”

13. The Packet Stuffing Party was scheduled to provide a full packet of registration materials, maps, and local highlights.

Project Fund and Scholarships— Christy Carello reviewed requests sub-mitted for funding, a good occasion to review our process for supporting funding requests.

Every year, we set a budget for Projects and for Scholarships. Proj-ect requests are submitted by the 4 December deadline and reviewed at the January board meeting. Scholar-ship requests are submitted by the 31 March deadline and reviewed at the April board meeting. These deadlines have been set up to be early enough to assist individuals in planning for their events.

We are not required to spend the entire amount of the budget, and we frequently (such as this year) vote to exceed our budget, if the requests mer-it it. Occasionally, in special circum-stances, we fund requests both outside the budget and after their deadlines.

We favor specific requests that can be planned carefully in advance and documented afterwards. We also re-quire a report of the results achieved to be written in some publication, such as Colorado Birds, or presented in a convention papers session.

Based upon this discussion, Ted Floyd moved, and Larry Modesitt sec-onded, that Johanna Beam be award-


ed $825 for one-half her expenses to attend a bird camp, Camp Chirica-hua. The motion passed. In addition, Christy Carello moved that fifth-grade teacher Joseph Boyle, of Mon-roe Elementary School in Colorado Springs, be awarded $475 for partial funds to attend Cornell University’s Bird Sleuth training for educators. This motion was seconded by Lisa Ed-wards and passed also.

Directors want to ensure that ap-plicants whose requests were not funded do not feel discouraged but to try again with closer adherence to our policy guidelines. The guidelines are described more fully on our website, www.cobirds.org.

Nominations—Chris Owens af-firmed that successors to retiring Di-rectors Mike Henwood and Larry Modesitt will be Gloria Nikolai and Amber Carver.

Awards—Chris Owens announced that all is in place for awards to be given at the banquet.

Future 2017 Convention: Doug Faulkner announced a consensus around Steamboat Springs for our 2017 convention, in mid to late June. He will recommend a date after re-viewing timing favorable for bird ac-tivity, road access, and cost for facili-ties. He also noted that with Western Field Ornithologists’ convention in Colorado in September, there will be two convenient sessions for Colorado birders. Some features of WFO’s con-vention could be worth adopting for Colorado conventions. In addition, it

is possible for participants to exchange birding experiences and information from birders from different regions.

CFO–Western Field Ornitholo-gists (WFO) Partnership—Larry Modesitt said that WFO’s 2016 Con-vention in Fortuna, California, 28 September to 2 October, also has the opportunity for superb leader Jon Dunn to lead a CFO trip from Sac-ramento to Fortuna. It will feature a pelagic trip (with unexpected possibil-ities) and stops for California special-ties not readily available at the WFO convention following.

Good landbird possibilities are California Thrasher, Towhee, and Quail; Mountain Quail; Wrentit; Tri-colored Blackbird; Oak Titmouse; Yellow-billed Magpie; Bell’s Sparrow; and White-headed Woodpecker. In-terested CFO members should contact Larry Modesitt at [email protected]. WFO is requesting support for field trips from CFO leaders.

Colorado Bird Records Commit-tee (CBRC)—Mark Peterson said the website is working well, but future im-provements are being compiled. Mark suggested a change in the CBRC Bylaws to permit a simplification for birders in submitting documentation for rare birds. If eBird documentation for rarities has been accepted and con-tains physical evidence (photographic or audio), it would not need to be sub-mitted to CBRC, unless identification is problematic.

CFO Website—David Gillilan said all is working well.


Social Media Communications —Christian Nunes reported more growth to 1,528 Facebook followers; Twitter followers are approximately 300.

Additional Committee Reports

Colorado Birds—Scott Gilli-han emailed to board members an advance copy of the spring edition which is excellent as always. Scott greatly appreciates previous editor Peter Burke’s sharing his experience and insights.

Scott would like the publication to be able to offer more color pages, which are costly, so this is a proposal that will be considered carefully in the future.

Publicity—Ted Floyd reported additional convention publication is unnecessary. Afterwards, he will in-clude in the website convention sum-mary a listing of all of the birds seen during the official field trips.

Membership—Lisa Edwards re-ported that we have grown to dis-tributing 602 issues of Colorado Birds. Automatic renewal is working well.

CFO Field Trips—Mike Hen-

wood will be leading two different trips for Sagebrush Sparrow on 16 and 17 April. Bill Kaempfer will of-fer an overnight trip to Craig, head-ing back through Wyoming sometime in midsummer. He also will lead trips to the northeast at the end of August and to Wray in October.

COBBA II Marketing—Doug Faulkner noted we’ve been posting quizzes and other information both in Facebook and on our website. Mike Henwood posted information in the Western Slope Birding Network. Lar-ry Modesitt will work with Western Field Ornithologists for publicity.

New Business: Bill Kaempfer recommended increasing the size of the CFO Board, as activities for directors have become far more in-volved. Each convention is more so-phisticated with more people, more field trips, more papers, a picnic, and Jeopbirdy. Pinning down convention and membership details is more time-consuming, despite the gains we’ve made in online assistance. We run quarterly CFO field trips. CBRC is more professional. Our partnership with Western Field Ornithologists re-quires coordination. We are receiving more help from volunteers, but this is vinsufficient to prevent over-burden-ing directors. This will be studied in the future.

The next board meeting will be at 11:00 on 10 September somewhere on the Front Range.

President Faulkner adjourned the meeting at 4:02 p.m., just in time for all board members to seek a nearby Golden-crowned Sparrow. All were successful excepting the finder of the Zonotrichia flock, your Secretary.

Respectfully submitted, Larry Modesitt, Secretary


Abstracts from the Papers Sessionin Lamar, May 7, 2016Christy Carello, papers session moderator

Approximately 75 avid birders took the afternoon off from birding at the CFO annual conference to at-tend presentations from students and experts in the field of ornithology. The chips, buzz, and chatter is that these avid birders felt the time listening to experts in an area of field ornithology was well worth the sacrifice of an af-ternoon in the field.

Attendees enjoyed learning about studies that will advance our knowl-edge about birds that will ultimately contribute to our ability to protect them and their habitat. Five of the nine presenters have received either grant or scholarship money from your generous contributions to the CFO project fund.

If you missed the presentation ses-sion or just want to refresh your mem-ory of the talks, we have included the abstracts in this issue for your reading pleasure.

Attempted nesting by Lilian’s Mead-owlark, Sturnella magna lilianae, in Boulder County, Colorado: A new latitudinal record for the taxon

Johanna Beam1 and Ted Floyd2 1244 Wichita Road, Lyons, CO

80540; [email protected] South Fork Drive, Lafayette,

CO 80026; [email protected] Eastern Meadowlark, Sturnella

magna, is very rare or casual in Colo-rado, and the relative statuses in Col-

orado of subspecies S. m. lilianae (“Lil-ian’s” Meadowlark) and nominate S. m. magna are not understood. We here present documentation of the occur-rence of the “Lilian’s” Eastern Mead-owlark in northern Boulder County during the summer of 2015.

Multiple birds, including a female and dependent young, were discov-ered and documented by Beam during the period 21 July–31 August. Photos and audio, contributed by Beam and other observers, establish the identi-fication on the basis of plumage and call notes.

This record constitutes the third or fourth for well-birded Boulder County of Eastern Meadowlark, and the first for lilianae. It appears to be the farthest north record anywhere for lilianae, and is notable for involving an apparent hybrid pairing (lilianae × Western Meadowlark, S. neglecta).

Many Colorado bird species are ex-periencing range shifts, and expansion northward is a particularly prominent aspect of the phenomenon. The Boul-der County “Lilian’s Meadowlarks,” rather than being an isolated discov-ery, thus may be part of a broader pattern of population change at the community level. In that vein, we en-courage all birders and field ornitholo-gists to try to understand vagrancy and range expansions in the context of large-scale and long-term avian popu-lation dynamics.


Effects of flooding on avian commu-nities: A Colorado case study

Francis Commercon 9396 South Morning Glory Way, Highlands Ranch, CO 80130; [email protected]

Riparian forests tend to sustain greater wildlife abundance and diver-sity per unit area than other land uses and thus hold particularly high value for wildlife conservation. Water re-source development, however, has sig-nificant impacts on riparian habitats in arid regions. A recently approved project in Chatfield State Park, Colo-rado, will increase the reservoir level during high precipitation years, pe-riodically inundating over 500 addi-tional acres of park land. How does periodic understory inundation im-pact avian communities? In May–June 2015, when natural flooding in the park mimicked water levels predicted under future management, I employed standardized point count surveys to compare bird densities in flooded and non-flooded forests. I also compared the Shannon–Weiner diversity index between the two habitat types.

I found that inundated forests do not show lower bird diversity. Species showed a range of responses to inun-dation. Four species showed no effects of inundation, two species (Yellow Warbler, Setophaga petechia; Western Wood Pewee, Contopus sordidulus) had higher densities in flooded forest, and two species (House Wren, Troglodytes aedon; Yellow-breasted Chat, Icteria virens) had lower densities in flooded forest. Species’ foraging strategies may explain preferences. Much of the for-est at risk of inundation in the park

will be cleared. However, this study indicates that periodically inundated forest still sustains avian diversity and is even preferred by some species, sug-gesting that leaving forest to be flood-ed would benefit avian communities.

Does rock climbing activity affect cliff-nesting birds and their associ-ated communities?

Nora Covy, School of Biological Sciences, University of Northern Col-orado, Ross Hall, Room 2480, Cam-pus Box 92, 501 20th Street, Greeley, CO 80638; [email protected]

Cliffs increase the diversity of or-ganisms by adding structural hetero-geneity within landscapes and serve as refuges for many unique species, including cliff-specialist birds. The recent increase in the popularity of rock climbing represents a novel dis-turbance to cliff ecosystems. In this study, I used a holistic approach to examine how rock climbing activity influences the distribution and behav-ior of avian species at cliff formations in Boulder Open Space and Mountain Parks (OSMP), Colorado. I conduct-ed surveys of birds at 16 high- and 16 low-climbing–use formations.

I found that cliff aspect was the strongest predictor of both avian di-versity and cliff use within this sys-tem. Lower avian species richness and diversity characterized high climb-ing use sites, but this pattern was driven by birds near cliffs rather than on cliffs. Contrary to expectation, Violet-green Swallows, Tachycineta thalassina, and White-throated Swifts, Aeronautes saxatalis, spent more time on cliffs at high-climbing–use sites


compared to low-climbing–use sites. Canyon Wrens, Catherpes mexicanus, were present for an equal amount of time at high- and low-use sites, but spent more time singing and foraging at low-climbing–use sites. Overall, my work showed that rock climbing does not have a major negative impact on birds that use cliffs in Boulder OSMP.

Tchep, check, tchip, chet: Dif-ferences between the call notes of “Audubon’s” and “Myrtle” Yellow-rumped Warblers, Setophaga coro-nata auduboni and S. c. coronata

Ted Floyd, 2009 South Fork Drive, Lafayette, CO 80026; [email protected]

The Yellow-rumped Warbler, Setophaga coronata, is probably the most familiar and most frequently detected warbler in Colorado. It oc-curs statewide on migration, it breeds extensively in Colorado’s mountain forests, and it is the only warbler that occurs regularly in winter in Colo-rado. Two subspecies, the Audubon’s, S. c. auduboni, and the Myrtle, S. c. coronata, occur in Colorado. Plum-age differences between auduboni and nominate coronata are well known to birders, as are differences between the call notes (or “chip notes”). But how, exactly, do these chip notes differ? I here present evidence for a diagnostic spectrographic difference between the two taxa, with the chip note of the Myrtle Warbler consisting of a rising element followed by a falling element, but with the chip note of the Audu-bon’s Warbler consisting of a double-banded rising element not followed by a falling element.

Warbler chip notes are variable,

and so it is within the Yellow-rumped Warbler complex. In particular, some Audubon’s Warblers on the breed-ing grounds may give call notes with Myrtle-like spectrographic signatures. Also, Colorado birders and field or-nithologists are regularly confronted with Audubon’s × Myrtle hybrids, whose chip notes may be intermedi-ate between those of the parental taxa. Nevertheless, typical chip notes of the two taxa are instantly recog-nizable spectrographically. In many instances, then, spectrograms of chip notes—easily obtained with current technology—can valuably support records of Myrtle and Audubon’s war-blers out of range.

Interspecific communication between Rock Wrens, Salpinctes obsoletus, and Canyon Wrens, Catherpes mexicanus

TJ Hathcock, College of Natural and Health Sciences, University of Northern Colorado, Ross Hall, Room 2480, Campus Box 92, 501 20th Street, Greeley, CO 80639; [email protected]

The Canyon Wren, Catherpes mexicanus, and Rock Wren, Salpin-ctes obsoletus, are closely related bird species that coexist while exploiting similar ecological niches in cliff habi-tats. Because they fill similar niches, it might be beneficial for them to communicate to better partition re-sources when living in close proxim-ity. To investigate if they use vocal signals to communicate, we tested whether the two species respond dif-ferently to playback stimuli of conspe-cific and heterospecific male song. We


measured and compared how quickly and how close males of each species approached the speaker in response to songs of both species. All vocal re-sponses were recorded for 45 minutes after each playback and allowed us to measure each song’s high frequency, low frequency, frequency range, maxi-mum frequency, duration, and number of syllables.

Using the approach response data, we found that males of both species significantly respond to conspecific playback but not to heterospecific playback. However, some individuals of both species did respond strongly to heterospecific playback by both ap-proaching and singing, suggesting that there may be some communication happening between the two species. We are now in the process of quanti-fying the song recordings, which may show changes in singing patterns in response to the different stimuli.

The teal housewives of Monte Vista: Strategies of nesting Cinna-mon Teal, Anas cyanoptera, in the San Luis Valley

Casey Setash, Colorado State Uni-versity, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, 1484 Campus Deliv-ery, Fort Collins, CO 80525; [email protected]

The Cinnamon Teal, Anas cyanop-tera, is an iconic species of the West, and breeds in higher densities in Colorado than nearly any other state. The foundation of effective waterfowl management is an abundant and re-silient waterfowl population, which begins with an understanding of what

drives population size and growth. Population growth rate is the product of a number of vital rates, all of which remain relatively unknown for Cin-namon Teal. In order to augment the information that currently exists, I am in the process of investigating several environmental (e.g., visual obstruc-tion rating, clutch size, and distance to water) and temporal factors (e.g., nest age and timing of incubation ini-tiation) affecting nest success of Cin-namon Teal on Monte Vista National Wildlife Refuge.

In 2015, my colleagues and I found 40 Cinnamon Teal nests with a nest success rate of 22.9%. Environmental factors around the nest had a greater influence on whether the nest was successful than did temporal factors. These results have strong implications for habitat management and, to some extent, contradict expected waterfowl life history strategies. This research project is ongoing, and more nests will be monitored over the 2016 and 2017 breeding seasons.

Geographic variation in the worn-out, shabbily dressed trumpeter (better known as the Rock Wren, Salpinctes obsoletus)

Garth M. Spellman, Department of Zoology, Denver Museum of Nature and Science, 2001 Colorado Boule-vard, Denver, CO 80205; [email protected]

The Rock Wren, Salpinctes obsole-tus, is a ubiquitous constituent of arid, rocky habitats in North America and Central America. Rock Wrens in Col-orado and the western U.S. all pertain to the widespread nominate subspe-


cies obsoletus, but the situation south of the U.S. border involves consider-ably more geographic variation than is the case here. Taxonomists during the mid-1900s recognized 14 subspecies of the Rock Wren, although subsequent examination of specimens suggested that much of the variation appears clinal, with the result that the number of subspecies was reduced to seven.

I am currently engaged in research that combines analyses of morphology, genetics, and vocalizations to explore geographic variation in the Rock Wren. Preliminary results from the analysis of morphological data suggest that the two Central American sub-species and the oceanic island subspe-cies (Isla San Benedicto and Isla Gua-deloupe) are easily distinguished from their mainland counterparts. Unlike Rock Wrens in Colorado and else-where in the U.S. and Mexico, these island and Central American popula-tions have longer, thicker and wider bills and shorter, less-convex wings. I will discuss the taxonomic and evo-lutionary implications of this work: How does this affect your checklist (taxonomy), and how do morphologi-cal characters differ between island birds and migrants (evolution)?

Observations of Canyon Wren, Catherpes mexicanus, nestling diet during prey delivery

Nathanial Warning1 and David Leatherman2

1Natural Resources Department, City of Longmont, 7 South Sunset Street, Longmont, CO 80501; [email protected]

2612 Stover Street #7, Fort Collins,

CO 80524; [email protected] identified prey items being

delivered by adult Canyon Wrens, Catherpes mexicanus, to nestlings on public lands in northern Colorado us-ing digital photography. Adult wrens delivered single invertebrate prey items from 11 orders in four classes: Insecta, Arachnida, Malacostraca, and Chilopoda. Within Insecta and Chilopoda, we describe invertebrates from four families not previously doc-umented as Canyon Wren prey: Noc-tuidae, Rhaphidophoridae, Formici-dae, and Scutigeridae.

Our observations align with previ-ous studies in other locations indicat-ing that insects and spiders are key components of the Canyon Wren diet. Moreover, our data show that ad-ditional locally available invertebrates including centipedes, isopods, and winged ants are captured to provision nestlings. Prey identification from digital imagery is a non-destructive sampling technique which can effec-tively be implemented for songbirds, and may be suited for citizen science monitoring programs on public lands.

Breeding ecology and productivity of the Gray Vireo, Vireo vicinior, on Kirtland Air Force Base

Lynne E. Wickersham1 and John L. Wickersham2

1Animas Biological Studies, 138 Overlook Drive, Durango, CO 81301; [email protected]

2Animas Biological Studies, 138 Overlook Drive, Durango, CO 81301; [email protected]

The Gray Vireo, Vireo vicinior, breeds only in the arid Southwest,


mainly in piñon–juniper woodlands. Relatively few data exist on their breeding ecology in Colorado or else-where. We monitored 196 Gray Vir-eo breeding territories and 145 nests across 8 years (2008–2015) on Kirt-land Air Force Base in New Mexico.

Territory size (based on minimum convex polygons) ranged from 0.4 to 23.7 ha (mean=4.5 ha). Return rate of color-banded males ranged from 30.0% to 77.8%; most males returned to the same territory in sub-sequent years. Nest success, based on exposure days and daily survival rate (DSR), varied widely across years, from a low of 9.5% to a high of 84.0% (mean=26.9%). Almost half of unsuc-cessful nests (49.4%) failed due to pre-dation. Brown-headed Cowbirds para-sitized 13.7% of nests across all years, though the proportion of parasitized nests declined from 2008 to 2015.

Host adults abandoned 50% of para-sitized nests after cowbirds laid one or two eggs, suggesting egg recognition by Gray Vireos. Only 20% (4) of par-asitized nests fledged cowbird young, and 5% (1) fledged cowbird and vireo young.

Statistical modeling indicates that year, mean tree height around the nest, and aspect influenced daily nest survival (DSR). The most compelling data suggest a slight positive effect for mean tree height on DSR. Nest-scale habitat models also point to the im-portance of mean tree height around the nest site, and suggest that Gray Vireos nested in areas with taller trees relative to available habitat within their territories. In 2016 we will initi-ate a new study in southwestern Col-orado to evaluate Gray Vireo nesting ecology at the northern limit of the species’ range.

Christy Carello, [email protected]


Robert Stockton Williamson(1824–1882)Bob Righter

The story of how the Williamson’s Sapsucker was discovered starts in the early 1800s with John Bell, a distinguished taxidermist and naturalist working out of his shop on Broadway and Worth Street in New York City. In 1843 Bell was invited to join John J. Audubon on his epic upper Missouri expedition. While on that expedition, Bell collected a previously unknown bird, which Audubon classified as a new vireo, naming it Bell’s Vireo. Even though Bell was always on the go, he nevertheless found time to teach an eleven year-old boy the skills of how to prepare bird skins—a boy who would later be known to the world as Teddy Roosevelt.

In 1849 Bell traveled to California on a collecting trip and re-turned with a female woodpecker he had never seen before. In 1852 John Cassin, the ornithologist at the Academy of Natural Sciences in Philadelphia, classified the new woodpecker, naming it Brown-headed Woodpecker Picus thyroideus. When Cassin’s book Illustra-tions of Birds of California was published, for some inexplicable rea-son he changed the name and sex of Bell’s original Brown-headed Woodpecker to a male Black-breasted Woodpecker, thus paving the way for decades of woodpecker confusion. Some wondered if the Brown-headed and Black-breasted woodpeckers were separate spe-cies or could it be that the Brown-headed was the female and the Black-breasted the male? Read on!

In 1849 Robert Stockton Williamson, after graduating from West Point, was assigned as one the topographic engineers surveying po-tential routes through the mountain passes of the Sierra Nevadas for a new Pacific Railroad route. Williamson was assigned to Captain William Warner’s expedition, which was surveying routes around the Yreka–Klamath region in California. While Captain Warner was on a reconnaissance mission, he was savagely attacked, his body riddled with arrows from a band of Pit River Indians. Williamson stepped up, took charge, located Warner’s body, took possession of the topo-graphic maps from his jacket, and gave him a dignified burial. He heroically continued with the survey, establishing his reputation as a trustworthy expedition leader.

In 1855 Williamson was assigned to lead an expedition assessing a railroad route from Los Angeles to San Francisco, and to Oregon and Washington. Williamson became sick along the way and returned to


San Francisco. Lieutenant Abbot, the new leader of the expedition, carried on with John Newberry, a Smithson-ian Museum–trained geologist and naturalist. On 23 August 1855, on the shores of Upper Klamath Lake, Oregon, Newberry collected a male woodpecker that was black and white with a yellow belly and a bright red chin. Newberry described and named this woodpecker Williamson’s Wood-pecker, Picus williamsoni. In 1860 Baird, Cassin, and Lawrence’s Birds of North America adequately described the male Williamson’s Woodpecker but naively declared that the female Williamson’s Woodpecker was like the male but its chin was less red and more whitish. Also in this publication, Spencer Baird reclassified the genus of the Brown-headed and Williamson’s woodpeckers from Picus (which con-tains such woodpeckers as the Hairy and Downy) to Melanerpes (which contains such woodpeckers as the Red-bellied), as being morphologi-cally and behaviorally different than other birds in the Picus genus.

With the beginning of the Civil War in 1860, Williamson was ordered to return east where he served on General Burnside’s staff and was commended for gallantry during the battle of New Bern, North Carolina. Then as a Lieutenant Colonel he joined General McClellan’s Army of the Potomac as chief Topographical Engineer. After the war he returned to the west coast, becoming an engineer with the lighthouse service.

As of 1873 there was no doubt within the ornithological com-munity that the Williamson’s Sapsucker and the Brown-headed Sapsucker were separate species. In 1873 Henry Henshaw, an experi-enced biologist assigned to the Wheeler Survey, was stationed in Fort Garland in the San Luis Valley, Colorado. One June day he decided to check out Mt. Baldy and see what birds were around. While trek-king in the mixed aspen and conifer forest, to his shock he found two different woodpecker species, the Williamson’s Sapsucker and Brown-headed Sapsucker, interacting and engaging in inappropriate behavior, one mounting the other! It didn’t take long for Henshaw

Robert S. Williamson. Photographer unknown, Library of Congress


to realize that the Brown-headed Sapsucker was actually the female of the Williamson’s Sapsucker. He couldn’t wait to get the word out, knowing the shock and awe other ornithologists would feel as a result of his discovery. In the first check-list of the American Ornitholo-gists’ Union in 1886 the name sapsucker became standardized in the Sphyrapicus genus, thus Williamson’s Sapsucker became the standard name we know today.

In June of 1882 Williamson, age 54, retired from the lighthouse service because of illness and died on November 10th while con-valescing in San Francisco. His name lives on, immortalized by his association with a most distinguished sapsucker.

FURTHER READINGGyug, L. W., R. C. Dobbs, T. E. Martin, and C. J. Conway. 2012. Williamson’s Sapsucker

(Sphyrapicus thyroideus). The Birds of North America Online (A. Poole, Editor). Cor-nell Lab of Ornithology, Ithaca, NY. http://bna.birds.cornell.edu/bna/species/285

Mearns, Barbara and Richard. 1992. Audubon to Xantus. Academic Press, San Diego, CA.

USGS. 2016. Henry Wetherbee Henshaw. http://www.pwrc.usgs.gov/resshow/perry/bios/henshawhenry.htm

Wikipedia. 2016. John Strong Newberry. https://en.wikipedia.org/wiki/John_Strong_Newberry

Wikipedia. 2016. Robert S. Williamson. https://en.wikipedia.org/wiki/Robert_S._Wil-liamson

Wikipedia. 2016. Wheeler Survey. https://en.wikipedia.org/wiki/Wheeler_Survey

Robert Righter, Denver, Colorado, [email protected]


THE HUNGRY BIRD

Breakfast at Jane’sDave Leatherman

Audrey Hepburn was a wonderful actress who considered her role in the 1961 Academy Award–winning movie “Breakfast at Tiffany’s” as among her most difficult. In the film this self-described introvert was asked to play an extrovert, Holly Golightly. I think Jane Stulp would say the same about the contrast between her own quiet per-sonality and her recent role as host to hungry birds and bird-hungry birders. During the 2016 Colorado Field Ornithologists Convention, 4–9 May in Lamar, birders paid over 400 visits to her yard!

Generally, those pilgrims were motivated by the hope of seeing eastern migrants and specifically, as luck would have it this year, a gorgeous, singing male Golden-winged Warbler. This taxon by most accounts has a troubled future due to habitat loss and genetic domi-nance by a relative, the Blue-winged Warbler. Considering both our prospects, each Golden-winged Warbler my aging eyes see takes on increasing significance.

This essay is about a minute creature that sustained the Golden-winged Warbler during its multi-day “Breakfast at Jane’s,” other birds targeting the same food item this spring, and details of how the prey was obtained. The insect, European elm flea weevil (Orchestes alni), was this column’s subject in the July 2012 (vol. 46 no. 3) issue of “Colorado Birds.” Like all good food, it is worth revisiting.

By way of review, the overwhelming majority of elms in Colorado are of two types: large-leafed American elm (Ulmus americana) and the smaller-leafed Siberian elm (U. pumila). Both trees are intro-duced in Colorado, the American from eastern North America, the Siberian from Asia.

American elm suffered major losses throughout most of its North American range to Dutch Elm Disease (DED), caused by a wilt fun-gus vectored by various bark beetles. However, due to an aggressive control program here and with the aid of an arid climate not all that conducive to fungal growth, many large-leafed elms survive in this state.

Following the droughts of the Dust Bowl in the 1930s and the Texas drought in the 1950s, Siberian elm was massively planted in Colorado, both east and west of the Continental Divide. This was mostly because they were one of the few trees capable of surviving our tough growing conditions. While not generally considered par-ticularly beautiful or special by standard human value systems, Sibe-rian elm persists in adversity and is the common tree in many parts


of rural Colorado. Somewhat of a “weed,” yes, but what would the streetscapes and farmyards of low-elevation Colorado look like with-out Siberian elm? And there is no denying their benefit to birds as nesting sites and hosts to edible arthropods.

Three insects commonly defoliate elms in Colorado: the elm leaf beetle (Xanthogaleruca luteola), the elm leafminer (Profenusa ulmi) and the European elm flea weevil. All are important diet items of Colorado birds in one or more of their life stages.

The elm leaf beetle (ELB) was introduced from Europe multiple times to North America in the 1800s. It was first reported as a pest in Baltimore, Maryland, over a century ago (Drooz 1985). It had spread to Colorado by the early 1900s and in the early years of my career as a tree entomologist beginning in 1974, it was the #1 “phone call in-sect.” The adult beetles chew round holes in leaves. The larvae skel-etonize leaves by chewing the green surface material (chlorophyll) between veins. The dingy yellow-green adults cause an additional problem by coming inside homes to overwinter. For many decades ELB dominated the leaf surfaces of Colorado elms and essentially had that niche to themselves. Likewise, birds learned to utilize ELB lar-vae and adults in their diets. The elm grove north of the main picnic shelter at Crow Valley Campground near Briggsdale in Weld County has traditionally been full of ELB and many good autumn migrant songbirds have been discovered by birders because of them.

Elm leafminer is another species introduced from Europe with an interesting history in Colorado. My early personal experience with it accrued almost entirely as a defoliator of American elm. Of late, it has expanded its ac-tivities to include Siberian elm. This species is in the group of stingless wasps that go by the common name of “sawflies.” Sawflies are flylike and get their name from the serrated egg laying organ of females. The blackish purple female elm leafminer lays her eggs in late spring along the central vein of an elm leaf. The resultant larvae make individual mines that radiate out from the main vein at roughly 45-degree angles, each mine bounded by major secondary veins. The resultant pattern looks like rather straight, wide, brown fingers coming off both sides of the main vein (Fig. 1). In my experience, few primetime migrants on the move extract the larvae from these mines because these birds are

Fig. 1. Elm leafminer larval mines in American elm in mid-summer at Grandview Cem-etery, Fort Collins. Photo by Dave Leatherman


mostly gone by the time the mines become conspicuous. Our nesting birds DO get them in late spring/early summer when the larvae drop out of the mines to the ground to pupate and transform into adults. I have seen species like robins and grackles readily chicken-picking larvae from sidewalks and other bare sur-faces that make the fallen larvae findable.

But what about “Breakfast at Jane’s”? European elm flea weevil (EEFW) is an Old World insect first reported in the Northeast of America in 1982 (Cranshaw 2006). It rather quickly spread to the Midwest, but its westward spread seemed to stall for decades (Drooz 1985). For unknown reasons, its march resumed and it was first reported from Colorado in my Fort Collins yard on 4 July 2006. Upon arriving here rather unexpectedly, quietly, and in huge numbers, it displaced ELB. What!? That is like a baseball team other than the New York Yankees dominating the American League. But dominate they did. No doubt the chant “Flea Weevils Rule!!!” could be heard throughout the crowns of Siberian Elms if you had freakish hearing like Mark Peterson, Duane Nelson, and Ted Floyd.

In another twist of the soap opera that is our natural world these days, EEFW suddenly disappeared and we began to see a resurgence of ELB. This is perhaps the result of the lowlands finally getting much-needed rain the past two sum-mers, but the mechanism for how these species shifts occurs remains a mystery. In yet another reversal of prominence, now in 2016 EEFW is “back.” As we all know, every year is Colorado is different and the word “typical” usually does not apply to anything involving the weather or natural organisms.

The EEFW winters as a tiny weevil in the soil and leaf litter under elms (see photos at various online sites). These weevils hop when disturbed, thus the descriptor “flea” in their common name. Shortly after the leaves come out in spring, the weevils fly up and lay eggs along the leaf margin, just a few per leaf. The eggs hatch and the larvae make meandering, ever-widening mines that usually terminate in a blotch near the leaf tip. A complete mine is a brown, somewhat oval area near the edge of the blade that on close examination shows a narrow meander where the freshly hatched larva began its feeding track (Fig. 2). Most of the feeding activity of the larval weevils within the mine takes place in late April and May. Pupation is within mines, with adults emerging in early summer. Adult weevils feed on leaves all summer, riddling them with nearly round holes. The jumpy adults are sought at this time by early fall migrant birds including Chipping Sparrows and Townsend’s Warblers. In late summer and autumn the weevils go to the soil for overwintering.

Many spring migrant birds have figured out elms are worth checking. One of the three defoliators mentioned above is usually present. In the case of EEFW, by keying in on the brown “defect” of mined leaves, a tiny morsel is usually available at the time of spring migration. Heavily infested trees can have weevil larvae in nearly every leaf (Fig. 2A). Despite their tiny size, apparently the effort to get them out of their hiding places within mines is worth the effort.

I watched the Golden-winged Warbler for a couple of hours on 5 May 2016


and, as usual with studying food acquisi-tion by birds, was impressed with the in-genuity and skill directed at this particu-larly difficult task. While certainly not a precise esti-mate, my guess would be lar-vae were being pulled from leaf mines at

the rate of 5–10 per minute. To see just what the larvae looked like and to get an apprecia-tion for what was involved in getting at them, I took a branch of infested leaves home to Janeal Thompson’s kitchen (don’t tell her). There, with good lighting, no wind, an insect pin dissection tool, and a glass of iced tea, I was a Golden-winged Warbler wannabe. I am humbled to say that what took me two hours to obtain (Fig. 3) took the little bird less than two minutes! But I learned something that enabled interpretation of recent field observations and photographs. The easiest way to get the larva out from each mine was to slice the surface of each mine along one edge with the tip of the pin. Then, one surface of the mine could be peeled back and the larva within easily seen and pulled out. What I kept seeing clearly in the field and photos was use of a foot by the

warbler while it fed. Once a mine with a telltale dark blob in the middle of a pale brown mine was in its sights (“locked on,” if you will), the bird held its position on a small branch with one foot and raised up the other foot to the mine. I do not have a viral video to prove it, but I strongly believe the slitting of the mine was carefully executed by a claw, and then the very sharp bill peeled it open and

Fig. 3. European elm flea wee-vil larvae and one pupa (up-per left, developing wing pads evident). Extraction by the au-thor of these larvae with an in-sect pin took about two hours. Photo by Dave Leatherman

Fig. 2A. A Siberian elm heavily infested by European elm flea weevil showing mul-tiple dark leaf mines. Lamar Community College Woods. May 2016. Photo by Dave Leatherman

Fig. 2. Individual Siberian elm leaf showing mine with Eu-ropean elm flea weevil larva within (dark object in center). Photo by Dave Leatherman


nipped the larva, all in one deft motion (Figs. 4 and 4A). Being blown away by this probably qualifies me for ridicule (at best) on Main Street in Lamar as “eas-ily amused,” but too bad, boys.

Further observation this spring has led me to believe that not all warblers are attracted to EEFW-infested elms, or at least have not mastered the techniques necessary to make the effort to obtain them worth it compared to the things they historically/instinctively know how to find. Yellow-rumped Warblers, for example, only rarely seemed interested in elm leaves this spring. Ditto for Or-ange-crowned Warblers. Other warblers that did seem interested were a Blue-winged at Tempel Grove, Northern Parulas, and Yellows. Had our experiment included all 50 or so North American warblers, my prediction would be interest in EEFW would have fallen out along generic lines.

Additional species that were clearly feasting on EEFW this spring in south-eastern Colorado were Lazuli Buntings, Indigo Buntings, Rose-breasted Gros-beaks, Black-headed Grosbeaks, Pine Siskins, American Goldfinches, House Finches, and House Sparrows. Interestingly, the finches, unlike the methodol-ogy of the warblers, tended to just bite into the entire mined area and pull out a bit of “salad.” Sort of like the seafood Caesar salad I like down at the bistro, within the greens were bits of protein. In the case of the birds and elm leaves, the protein was in the form of weevil larvae and pupae. After obtaining some practice at checking infested leaves, those fed upon by finches tended to have a big bill-shaped “V” chomped out of the tip and very little to no brown mined areas showing (Fig. 5).

This story is one that will surely continue to change and evolve. It involves a mix of native and introduced birds, introduced trees, and introduced insects. Clearly birds are opportunists capable of figuring out most of the hands we and Mother Nature deal. Native plants and native insects normally work best for native birds, but a world featuring a predominance of such interactions seems increasingly elusive. In the interim, as birders it behooves us to simply try and figure out the real world, as messed up as it is. By so doing, maybe we can slowly skew things back in the right direction with more intelligence than we would if simply not paying attention to anything more than checklists.

Meanwhile back at Stulp Farms, I am sure the lucky kids of Jane and John Stulp found breakfast inside their home to be a nurturing experience. Outside in the yard, the birds seemed to agree.

LITERATURE CITEDCranshaw, W. 2006. European elm flea weevil. Colorado Insect of Interest Series (http://

bspm.agsci.colostate.edu/files/2013/03/European-Elm-Flea-Weevil.pdf), Colorado State University, Fort Collins, CO.

Drooz, A. T. (Ed.). 1985. Insects of eastern forests. USDA Forest Service Miscellaneous Publication No. 1426. U.S. GPO, Washington, DC.

Dave Leatherman, [email protected]


Fig. 5. Leaf infested by European elm flea weevil showing V-shaped notch at leaf tip where an unknown bird, probably a House Finch, removed in one bite most of the mine and the larva within. 5 July 2008, Fort Collins. Photo by Dave Leatherman

Fig. 4. Golden-winged Warbler using foot to assist removal of a Eu-ropean elm flea weevil larva from elm leaf at the Stulp Farms yard on 5 May 2016. Photo by Janeal Thompson

Fig. 4A. Golden-winged Warbler at the moment of European elm flea weevil larva re-moval from an elm leaf at the Stulp Farms yard on 5 May 2016. Photo by Janeal Thompson


NEWS FROM THE FIElD

Winter 2015–2016(December–February)David Dowell

“News from the Field” contains reports of rare birds found in Colorado. These reports are compiled from eBird (ebird.org), the

American White Pelican, John Martin Reservoir, Bent County, 10 Febru-ary 2016. Photo by Dave Leatherman

Cooper’s Hawk, Centennial Trail, Boulder County, 5 March 2016. Photo by Jane Baryames

Northern Shoveler, Rocky Mountain Arsenal, Adams County, 27 February 2016. Photo by Jane Baryames

American Woodcock, Bobcat Ridge Nat-ural Area, Larimer County, 21 January

2016. Photo by Dave Leatherman


Lazuli Bunting, Gardens on Spring Creek, Fort Collins, Larimer County, 21 December 2015. Photo by Dave Leatherman

Yellow-throated Warbler, Mountain Av-enue, Fort Collins, Larimer County, 21 December 2015. Photo by Dave Leatherman

Red-bellied Woodpecker, Padroni, Lo-gan County, 28 December 2015. Pho-to by Todd Deininger

Ladder-backed Woodpecker, Hasty Lake, Bent County, 13 February 2016. Photo by Janeal Thompson


COBirds listserv ([email protected]), and the West Slope Birding Network ([email protected]). The reports contained herein are largely unchecked, and the editors do not necessarily vouch for their authenticity. Species in capitals are those for which the Colorado Bird Records Committee (CBRC) requests documen-tation. Please submit your sightings of these “review” species through the CFO website at coloradobirdrecords.org.

Season OverviewWinter 2015–2016 was a relatively mild one in Colorado—cold

but not extremely cold. Presumably this mild weather was a factor in the surprising winter bird finds described below. Although the state did not experience extremely cold weather, lakes still remained ice covered throughout the winter because nights were cold enough and winds were lighter than usual.

For the second year in a row, an American Woodcock found a winter home at Bobcat Ridge Natural Area, feeding in a spring-fed stream in the foothills near Masonville (Larimer). A second Ameri-can Woodcock was found in the same area soon after the first bird was discovered, and both birds remained in the area for a month. Colorado bird fans eagerly await the sequel American Woodcock III in winter 2016–2017.

For the first time, White-throated Swifts were documented win-tering in Colorado: 200 late swifts seen on 1 Nov near Pueblo Reser-voir (Pueblo) were a first indicator of this unusual event. At various times between 23 Nov and 16 Feb, the swifts were observed in the same area. Several were typically seen at any one time, but over 100 were observed on 20 Dec. A single White-throated Swift seen on 24 Dec in the canyon country south of La Junta (Otero), far away from Pueblo Reservoir, could indicate that the swifts wintered at multiple locations in southern Colorado.

Other surprising finds in winter 2015–2016 included Lazuli Bun-ting in Larimer (unprecedented in winter), Western Tanager (La Plata), Lark Sparrow (Mesa), Ovenbird (La Plata), Eastern Phoebes (El Paso and Pueblo), and Spotted Sandpipers (found at five different locations!). Also, birders were treated to good looks at long-staying rare birds on private property: Yellow-throated Warbler (Larimer), Carolina Wren (Jefferson), and Varied Thrushes (Grand and Lar-imer). The hospitality of the homeowners at these locations is greatly appreciated.

In the list of reports below, county names are italicized, and the fol-lowing abbreviations are used: CFO – Colorado Field Ornithologists; CG – campground; m.ob. – many observers; NA – Natural Area;


Sharp-tailed Grouse, northwest of Crook, Logan County, 27 December 2015. Pho-to by Kathy Mihm Dunning

NHS – National Historic Site; NP – National Park; NWR – National Wildlife Refuge; Res. – Reservoir; SP – State Park; STL – State Trust Lands; SWA – State Wildlife Area.

Greater White-fronted Goose: 380 near Prewitt Res., Washington, 20 Feb (Kathy Mihm Dunning, Da-vid Dowell). Other reports from Ad-ams, Arapahoe, Bent, Boulder, Denver, Douglas, El Paso, Fremont, Jefferson, Larimer, Logan, Morgan, Prowers, Pueblo, Sedgwick and Weld, 2 Dec–28 Feb.

Greater White-fronted x Cackling Goose (hybrid): 1 at Fort Logan Cem-etery, Denver, 6 Dec (Art Hudak). 1 at Memorial Park & Prospect Lake, El Paso, 10 Dec (Bill Maynard). 1 at Windsor Res., Weld, 26 Feb (Steven Mlodinow, Kathy Mihm Dunning).

Trumpeter Swan: 10 (4 Dec)

and then 5 (29 Dec–3 Jan) at High-line Lake State Park, Mesa (Eileen Cunningham, Carol Ortenzio, Mike Henwood, Leon Thurmon, Denise & Mark Vollmar, m.ob.). 7 at Loma, Mesa, 6 Dec (David Price). 1 at Union Res., Weld, 6–8 Dec (Jack Bushong, Ryan Bushong, Holden Maxfield, m.ob.). 2 near Hygiene, Boulder, 9–13 Dec (Carl Starace, m.ob.). 2 at South Platte Res., Jefferson/Arapahoe, 29–31 Dec (Mark Chavez, Steve Miller, m. ob.). 2 at LUNA Res., Weld, 31 Dec (William Kaempfer). 2 at Standley Lake, Jefferson, 1–2 Jan (Jen Ottinger, m.ob.). 1 at Sands Lake SWA, Chaffee, 1 Jan (Jack Harlan, Sherrie York). 2 at Wheat Ridge Greenbelt, Jefferson, 4 Jan (Dick Schottler, m.ob.). 5 at Jerry Creek Res. SWA, Mesa, 5–13 Jan (Denise & Mark Vollmar, m.ob.). 4 in Grand Junction, Mesa, 22 Jan–12 Feb (Carol Ortenzio, Nic Korte). 6 at Parachute, Garfield, 5–9 Feb (JoAnn Riggle, Scott Somershoe).

Tundra Swan: 3 at Sweitzer Lake, Delta, 2 Dec (Scott Jorgensen). 1 at Valmont Res., Boulder, 4 Dec–16 Feb (Jeff Parks, m.ob.). 1 at McIntosh Res., Boulder, 5 Dec (Steve Frye). 2 at Douglas Res., Larimer, 19 Dec (Denise Bretting, Casey Setash). 5 at Elev-enmile SP, Park, 22 Feb (David Sud-djian).

Mallard x Mottled Duck (hybrid): 1 at Denver City Park, Denver, 7 Feb (Ted Floyd).

Blue-winged Teal: 2 at Valco Ponds SWA, Pueblo, 3–5 Dec (Steven


Sharp-shinned Hawk, LCC Woods, La-mar, Prowers County, 3 February 2016. Photo by Janeal Thompson

Greater Yellowlegs, private Lake Mc-Clave, Bent County, 13 February 2016. Photo by Janeal Thompson

Mlodinow, Dale Adams). 2 near Fort Collins, Larimer, 19 Dec (Denise Bret-ting, Casey Setash).

Surf Scoter: 2 at Chatfield SP, Jef-ferson, 1 Dec (David Suddjian).

White-winged Scoter: 1 at Hol-brook Res., Otero, 2–16 Dec (Stanley Oswald, m.ob.). 1 at South Platte Res. and nearby McLellan Res., Jefferson/Arapahoe, 7–26 Dec (Nelson Ford, m.ob.)

Black Scoter: 1 at Holbrook Res., Otero, 7–16 Dec (Stanley Oswald, m.ob.).

Long-tailed Duck: 8 at Pueblo Res., Pueblo, 1–3 Jan (Joey Kellner, Kathy Mihm Dunning, Cheryl Teu-ton, Charles Lawrence, Dean Shoup, Joe Roller, David Dowell, Loch Kil-patrick, Glenn Walbek). Other re-ports from Arapahoe, Douglas, El Paso, Fremont, Jefferson, Logan, Mesa, Moffat, Pueblo, Sedgwick and Weld, 3 Dec–26 Feb.

Ring-necked Pheasant: 149 near Crook, Logan, 3 Jan (Kathy Mihm Dunning, Joey Kellner).

White-tailed Ptarmigan: As many as 28 at Guanella Pass, Clear Creek, 14 Jan–10 Feb (Doug Kibbe, Judith Hen-derson, Melissa James, Chuck Aid).

Pacific Loon: 1 at Rawhide En-ergy Station/Hamilton Res., Larimer, 6–7 Dec (Andy Bankert, m.ob.). 1 at John Martin Res., Bent, 15 Dec–1 Jan (Duane Nelson, Mark Peterson, Kathy Mihm Dunning, Janeal W. Thompson).

Common Loon: Reports from Arapahoe, Bent, Boulder, Denver, Douglas, Huerfano, Jefferson, Larimer, Pueblo, Routt, and Weld, 1 Dec–28 Feb.

Red-necked Grebe: As many as 3 at Pueblo Res., Pueblo, 25 Nov–13 Feb (Chris Knight, Brandon Percival, Bill Maynard, m.ob.). 1 at Rawhide En-ergy Station/Hamilton Res., Larimer, 6–7 Dec (Andy Bankert, m.ob.). 1 at Douglas Res., Larimer, 16 Dec (Andy Bankert). 1 at Lory SP, Larimer, 19


Dec (Andy Bankert). 1 at Horsetooth Res., Larimer, 19 Dec (Andy Bankert). 1 at Black Hollow Res., Weld, 22 Feb (Steven Mlodinow).

Sora: 1 at Mogeson Ponds SWA near Mesa, Mesa, 1 Dec (Mike Hen-wood). 2 near Mack, Mesa, 4 Dec (Carol Ortenzio, Eileen Cunningham, Mike Henwood). 1 at John Martin Res., Bent, 15 Dec (Lisa Edwards). 1 at Rocky Ford SWA, Otero, 16 Dec (Lisa Edwards, Kathy Mihm Dunning). 1 at Cherry Creek SP, Arapahoe, 4–24 Jan (Loch Kilpatrick, Gene Rutherford). 1 in Colorado City, Pueblo, 17 Jan (Dave Silverman).

White-faced Ibis: 1 at Lake Hasty, Bent, 11 Dec (Duane Nelson).

Spotted Sandpiper: 1 in Pagosa Springs, Archuleta, 1 Dec (Ben Bai-ley). 1 in Glenwoood Springs, Gar-field, 4 Dec–25 Jan (JoAnn Riggle). 1 in Grand Junction, Mesa, 20 Dec (JoAnn Riggle). 1 in Durango, La Pla-ta, 23 Dec (m.ob.). 1 at Pueblo Res., Pueblo, 14 Feb (Brandon K. Percival).

Dunlin: 2 at Lake Loveland, Lar-imer, 29 Nov–11 Dec (Irene Fortune, m.ob.).

AMERICAN WOODCOCK: 1 (1Jan–15 Feb) and then 2 (4 Jan–7 Feb) at Bobcat Ridge NA, Larimer (David Wade, Cole Wild, Heather Wild, m.ob.).

Red Phalarope: 1 at Pueblo Res., Pueblo, 18 Jan (Bill Maynard, Richard Bunn, Stephany McNew).

Bonaparte’s Gull: 210 at Pueblo Res., Pueblo, 3 Dec (Steven Mlodi-now).

Mew Gull: 1 adult at Cherry Creek SP, Arapahoe, 21 Nov–13 Dec (Glenn Walbek, m.ob.). 1 juvenile at Cherry

Creek SP, Arapahoe, 6–14 Dec (Scott Somershoe, m.ob.). 2 adults at Valco Ponds SWA, Pueblo, 3 Dec (Steven Mlodinow). 1 adult at Douglas Res., Larimer, 6–10 Dec (Andy Bankert, David Wade). 1 subadult at Larimer County Landfill, Larimer, 12 Dec (Nick Komar, Andy Bankert, David Wade). 1 first cycle and 1 subadult at Horseshoe Res., Larimer, 20 Dec (Nick Komar, Jon Cobble, Georgia Doyle). 1 adult and 1 immature at Anthem Ranch Ponds, Broomfield, 23 Dec (Steven Mlodinow). 1 adult at John Martin Res., Bent, 1 Jan (Steven Mlodinow). 1 adult at Pueblo Res., Pueblo, 17–29 Jan (Stephany McNew, m.ob.). 1 immature at Valmont Res., Boulder, 26 Jan (David Dowell). 1 first cycle at Windsor Lake, Weld, 17 Feb (Steven Mlodinow). 1 adult at Windsor Lake, Weld, 20–22 Feb (Da-vid Dowell, Kathy Mihm Dunning, m.ob.). 1 first cycle at Black Hollow

Long-eared Owl, Tamarack Ranch, Lo-gan County, 30 January 2016. Photo by Kathy Mihm Dunning


Res., Weld, 22–23 Feb (Steven Mlodi-now). 1 adult at Union Res., Weld, 29 Feb (Steven Mlodinow).

ICELAND GULL: 1 (Dec 18) and then 2 adults (Jan 5) at Aurora Res., Arapahoe (David Dowell). 1 adult at Windsor Lake, Weld, 13 Feb (David Dowell, Steven Mlodinow). 1 adult at Boyd Lake, Larimer, 21 Feb (Glenn Walbek, Mark Peterson, Steve Larson).

GLAUCOUS-WINGED GULL: 1 first cycle at Boyd Lake and Lake Loveland, Larimer, 21–22 Feb (Steve Larson, Mark Peterson, Glenn Wal-bek, Joe Mammoser).

Glaucous Gull: Reports from Arapahoe, Bent, Denver, Douglas, Jef-ferson, Larimer, Pueblo, and Weld, 1 Dec–26 Feb.

Great Black-backed Gull: 1 adult female, returning for the 22nd consec-utive winter, at Pueblo Res., Pueblo, 23 Nov–20 Feb (Stephany McNew,

Brandon K. Percival, m.ob.). 1 adult at Chatfield SP, Douglas, 5–7 Dec (Jesse Casias, Christine Alexander). 1 adult and 1 first cycle at John Martin Res., Bent, 4–8 Feb (Duane Nelson, Steven Mlodinow, Kathy Mihm Dunning). 1 adult at Lake Loveland, Larimer, 26 Feb (Janeal Thompson).

Band-tailed Pigeon: 2 near Flor-ence, Fremont, 5–12 Feb (Dale Ad-ams). 1 in Maysville, Chaffee, 14 Feb (Jeff Guy).

Western Screech-Owl: 86 in Grand Junction, Mesa, 20 Dec (Nic Korte).

Northern Saw-whet Owl: 10 in Big Thompson canyon, Larimer, 1 Jan (Andy Bankert).

SNOWY OWL: 1 near Denver International Airport, Denver/Adams, 5–9 Dec (Bill Hutchinson, Jonnie Thompson, m.ob.). 1 juvenile near Chatfield SP, Douglas, 20 Dec (Steve Stachowiak). 1 near Sedgwick, Sedg-wick, 29 Dec (Lori Zabel). 1 in Colo-rado Springs, El Paso, 12 Jan (Tena & Fred Engleman).

Burrowing Owl: 1 near Denver International Airport, Denver, 7 Dec (m.ob.). 1 at Big Johnson Res., El Paso, 12–27 Feb (Alan Versaw, m.ob.).

White-throated Swift: Several to over 100 near Pueblo Res., Pueblo, from 23 Nov–16 Feb (Stephany Mc-New, Margie Joy, Aaron Driscoll, m.ob.). Perhaps many of the ap-proximately 200 swifts seen on 1 Nov (Brandon K. Percival) remained in the area. Another White-throated Swift was seen south of La Junta, Otero, on 24 Dec (Duane Nelson).

Belted Kingfisher: 18 near Fort Morgan, Morgan, 16 Dec (Doug Kibbe).

Hermit Thrush, Tamarack Ranch, Lo-gan County, 30 January 2016. Photo by Kathy Mihm Dunning


ACORN WOODPECKER: 1 in Colorado Springs, El Paso, 18 Dec–18 Feb (Marty Wolf, m.ob.). Other reports of ongoing birds in Durango (La Plata) and Pueblo Mountain Park (Pueblo).

Black Phoebe: 1 near Grand Junc-tion, Mesa, 2–26 Dec (Mike Henwood, Eileen Cunningham, m.ob.). 1 near Pueblo Res., Pueblo, 9 Dec–6 Feb (Jane Stulp, m.ob.). 1 in Pueblo, Pueblo, 19–29 Dec (John Drummond, Dan-iel Maynard, Van Truan). 1 in Cañon City, Fremont, 20 Dec–21 Feb (Lisa Edwards, Rich Miller, Dale Adams). 1 near Florence, Fremont, 13 Dec–6 Feb (SeEtta Moss, Dale Adams, m.ob.). 1 near Hotchkiss, Delta, 2–9 Jan (Dennis Garrison, Bill Harris, Jason Beason).

Eastern Phoebe: 1 near Fountain, El Paso, 14 Dec (Mark Peterson). 1 near Pueblo, Pueblo, 27 Feb (Brandon K. Percival).

Red-breasted Nuthatch: 150 in Ai-ken Canyon Preserve, El Paso, 18 Jan (Alan Versaw).

House Wren: 1 in Pueblo, Pueblo, 19 Dec–23 Jan (Daniel Maynard, Kathy Mihm Dunning, Joey Kellner). 1 near Colorado City, Pueblo, 25 Dec (Dave Silverman). 1 at Brett Gray Ranch, Lincoln, 30 Jan (Mark Peterson).

PACIFIC WREN: 1 near Rye, Pueblo, 24 Dec (Dave Silverman). 1 at Carrizo Canyon Picnic Area, Baca, 13 Feb (Jeff Calhoun).

Winter Wren: Reports from Baca, Boulder, Denver, Douglas, El Paso, Fre-mont, Jefferson, Larimer, Mesa, Pueblo and Washington, 7 Dec–19 Feb.

Carolina Wren: 1 in Wheat Ridge, Jefferson, late Nov–12 Feb (Patty Ech-elmeyer, m.ob.). 1 in Beulah, Pueblo, 3 Jan (Van Truan).

Blue-gray Gnatcatcher: 2 near Pueblo Res., Pueblo, 5 Dec–18 Jan (Dale Adams, Charles Hundertmark, Paul Slingsby).

Golden-crowned Kinglet: 26 at Deer Creek Canyon Park, Jefferson, 19 Dec (Kathy Mihm Dunning). 24 at Lory SP, Larimer, 19 Dec (Andy Bankert). Numerous reports elsewhere, including on the eastern Colorado plains.

Eastern Bluebird: 1 near Carbon-dale, Garfield, 16 Jan (Dick Filby); first county record.

Hermit Thrush: Reports from Baca, Boulder, Denver, Douglas, Fre-mont, Jefferson, La Plata, Logan, Mesa, Morgan, Otero, Pueblo, San Miguel, Washington, and Yuma, 2 Dec–28 Feb.

Varied Thrush: 2 in Granby, Grand, 29 Nov–29 Jan (Cathy Craig, m.ob.). 1 in Lakewood, Jefferson, 17–19 Dec (Robert Raker). 1 near Cherry Creek Res., Arapahoe, 1 Jan (Rebecca Camp-bell). 2 in Larimer northwest of Lyons, 11–31 Jan (Donna Nespoli, m.ob.).

Gray Catbird: Reports from Boul-der, El Paso, Jefferson, Kit Carson, Lar-imer, Logan, Otero and Weld, 7 Dec–22 Feb.

Brown Thrasher: 1 at Rocky Ford SWA, Otero, 16 Dec (Kathy Mihm Dunning, Lisa Edwards). 1 near Ster-ling, Logan, 28 Dec (Jeff Dawson). 1 at Two Buttes SWA, Baca, 1 Jan (Steven Mlodinow). 1 near Boulder, Boulder, 17 Jan (Jeff Parks). 1 in Colorado City, Pueblo, 24 Feb (Dave Silverman).

Northern Mockingbird: 1 along Colorado River north of Dotsero, Ea-gle, 13 Dec (Cait Boyd). Other reports from Fremont, Larimer, Otero, Pueblo, and Yuma, 12 Dec–23 Jan.


Cedar Waxwing, Chautauqua Park, Boulder County, 26 February 2016. Photo by Jane Baryames

European Starling: 150,000 near Kersey, Weld, 27 Jan (Kathy Mihm Dunning, Steven Mlodinow).

Bohemian Waxwing: 10 west of Livermore, Larimer, 24 Dec (Morris Clark).

Lapland Longspur: 12,000 near Grover, Weld, 10 Jan (Chris Wood).

Snow Bunting: Reports from Ad-ams and Weld, 8 Dec–10 Jan.

Ovenbird: 1 in Durango, La Plata, 24 Dec (Kristi Dranginis).

Yellow-throated Warbler: 1 in Fort Collins, Larimer, 5 Dec–28 Feb (Luke Caldwell, Jeffrey Birek, m.ob.).

Pine Warbler: 1 in Littleton, Arap-ahoe, 16–18 Dec (Carol Blackard).

Field Sparrow: 1 at Higbee, Otero, 12 Dec (Stanley Oswald). 1 near Jules-burg, Sedgwick, 14 Dec (Steven Mlodi-now).

Lark Bunting: 20 near Pueblo, Pueblo, 9 Feb (Clark Jones).

Lark Sparrow: 1 in Mack, Mesa, 21 Jan (Nic Korte).

Fox Sparrow: 1 (Slate-colored) at No Name, Garfield, 7 Dec–6 Feb (Thomas C. McConnell). 1 (Red) in Wellington, Larimer, 15 Dec (Fawn Si-monds). 1 near Weldona, Morgan, 16 Dec (William Kaempfer). 1 (Red) near Idalia, Yuma, 17 Dec (Glenn Walbek). 1 (Red) near Bonny SWA, Yuma, 18 Dec (Glenn Walbek). 1 (Red) at Bear Creek Park, Denver, 19 Dec (George Mayfield, Michael Kiessig, Martha Eu-banks). 1 in Durango, La Plata, 23 Dec (Marlene Pixler). 1 (Slate-colored) at Fruitgrowers Res., Delta, 7–15 Jan (Dave Galinat).

Golden-crowned Sparrow: 1 adult, returning for its sixth consecutive win-ter, at Teller Farm & Lakes, Boulder, 25

Oct–8 Jan (David Dowell, m. ob.). 1 at Olive Marsh in Pueblo, Pueblo, 19 Dec (Daniel Maynard). No sightings at Red Rocks Park (Jefferson) this winter.

Harris’s Sparrow: 1 in Meeker, Rio Blanco, 24 Dec (H. David Chapman). 1 in La Veta, Huerfano, 27 Dec (Gwen Moore). 1 in Delta, Delta, 5 Jan (Ja-son Beason). 1 in Rifle, Garfield, 4 Feb (Art Dahl). Other reports from Adams, Bent, Boulder, Denver, El Paso, Fre-mont, Jefferson, Larimer, Morgan, and Otero, 5 Dec–13 Feb.

White-throated Sparrow: 1 at State Forest SP, Jackson, 6 Dec–16 Jan (Kevin Keirn, Brent Thordarson, Brandon Nooner, Todd Deininger). 1 in Nucla, Montrose, 13 Dec (Coen Dexter). 1 in Carbondale, Garfield, 8 Jan–20 Feb (Dick Filby). 1 in Ouray, Ouray, 20 Jan (Lillian McMurrin). Other reports from Adams, Arapahoe, Boulder, Denver, Douglas, Fremont,


Bullock’s Oriole, Willow Creek south of LCC Woods, Lamar, Prowers County, 11 February 2016. Photo by Dave Leatherman

Huerfano, Jefferson, Las Animas, Mesa, Morgan, Otero, Prowers, and Pueblo, 1 Dec–21 Feb.

Vesper Sparrow: 1 near Las Ani-mas, Bent, 8 Feb (Steven Mlodinow, Kathy Mihm Dunning). 1 near Ar-riba, Lincoln, 17 Feb (Glenn Walbek).

Savannah Sparrow: 1 near Ar-riba, Lincoln, 8 Dec (Glenn Walbek). 1 at Big Johnson Res., El Paso, 24 Feb (Alan Versaw).

Swamp Sparrow: Reports from Adams, Arapahoe, Boulder, Douglas, Fremont, Jefferson, Kiowa, Larimer, Logan, Morgan, Otero, Pueblo, and Weld, 3 Dec–19 Feb.

Green-tailed Towhee: 1 at Bear Creek Lake Park, Jefferson, 18 Dec (Mark Amershek, Bruce Neuman). 1 in Steamboat Springs, Routt, 10 Dec (Lisa Williams). 1 at Cottonwood Canyon, Baca, 21 Dec (Sean Walters, Steven Mlodinow). 1 near Hotchkiss, Delta, 6 Jan (Jason Beason, Dennis Garrison). 1 near Yuma, Yuma, 24 Jan–21 Feb (Jane Stulp).

EASTERN TOWHEE: 1 near Pueblo, Pueblo, 22 Dec (Mark Peter-son).

Western Tanager: 1 in Durango, La Plata, 17 Dec (Riley Morris).

Lazuli Bunting: 1 in Fort Collins, Larimer, 19 Dec (Rachel Hopper).

EASTERN MEADOWLARK: 1 near Deer Trail, Arapahoe, 13 Feb (Gene Rutherford).

Rusty Blackbird: 2 at Barr Lake SP, Adams, 30 Nov–1 Dec (Norm Er-thal). 1 near Pueblo Res., Pueblo, 3 Dec (Brandon Percival). 1 at Florence River Park, Fremont, 20 Dec (Dale Adams). 1 in Pagosa Springs, Ar-chuleta, 29 Dec–6 Jan (Byron Greco,

Ben Bailey). 1 at South Platte Park, Arapahoe, 2 Jan (Doug Shoffner, Chip Clouse, Pablo Quezada). 1 near Foun-tain, El Paso, 16 Jan – 17 Feb (Bill Maynard, Mark Peterson, m.ob.).

Common Grackle: Reports from Bent, Boulder, Delta, Denver, Douglas, Jefferson, Kiowa, Larimer, Logan, Mor-gan, Pitkin, Pueblo, Sedgwick and Weld, 7 Dec–29 Feb.

Bullock’s Oriole: 1 near Pueblo, Pueblo, 22 Dec (Lisa Edwards, Mark Peterson). 1 in Lamar, Prowers, 10 Feb (Jill White Smith, Dave Leatherman).

PURPLE FINCH: 1 female type at Fountain Creek Regional Park, El Paso, 14–16 Dec and 10 Jan–3 Feb (Ted Floyd, Robb Hinds, m.ob.).

Common Redpoll: Found at many locations this winter, particularly in northern Colorado; reports from Ad-ams, Bent, Boulder, Clear Creek, Doug-las, El Paso, Garfield, Grand, Jackson, Jefferson, Larimer, Logan, Montrose, Routt, Sedgwick, Summit, Weld, and Yuma, 13 Dec–18 Feb.


ACKNOWLEDGMENTSThe sightings reported by contributing observers to eBird, COBirds, and the West Slope Birding Network are greatly appreciated. Volunteer compilers contributed significantly to this report: Jim Beatty (southwest), Coen Dexter (west), John Drummond (south-east), Forrest Luke (northwest), Rich Miller, Brandon Percival, and David Silverman. Much of the information in this report was obtained from the eBird Basic Dataset from the Cornell Lab of Ornithology, Ithaca, New York.

David Dowell, [email protected]

CFO Sagebrush Sparrow Field Trips: 16 & 17 April 2016Mike Henwood

When planning the Sagebrush Sparrow field trips, I envisioned walking down a dirt road on a sunny morning with Sagebrush Spar-rows singing from both sides of the road. Cold reality turned out to be quite the opposite with a weekend of cold and snow across the state. Snow closed the mountain passes and most of the folks from the East-ern Slope were forced to cancel their trips across the mountains. One participant from Denver made it for the Saturday trip, and one on Sunday, plus we had three other local birders on the Sunday trip.

Saturday was a tough day and Robert Beauchamp and I battled snow, cold, wind, and rain during most of the day. We were con-cerned about the condition of the dirt roads west of Mack, so we headed to the Glade Park area above Colorado National Monument to look for Sagebrush Sparrows and ran into blowing snow. On Sun-day our group battled cold and windy conditions, but everyone was able to see a Sage Thrasher at close range and several singing Sage-brush Sparrows. Other highlights included flushing a group of six Long-billed Curlews, a first-of-the-season Northern Mockingbird, a pair of courting Loggerhead Shrikes, a singing Brewer’s Sparrow, mi-grating Mountain and Western Bluebirds moving through the desert area, and a male Cassin’s Finch in the junipers. We also were able to observe a Bald Eagle, Great Horned Owl, Red-tailed Hawk, and Common Raven all sitting in nests.

Mike Henwood, Grand Junction, Mesa County

CFO FIElD TRIP REPORT


IN THE SCOPE

Yellow-rumped Warblers: AnUnder-Appreciated FieldIdentification ProblemTony Leukering

When is a Colorado Yellow-rumped Warbler (Setophaga coronata) referable to neither Myrtle nor Audubon’s? When it combines genes of both!

In Colorado, we birders are fairly savvy when it comes to identify-ing birds to the subspecies level, what with birding in a biogeographic wonderland of East meets West. We are also fairly comfortable with the incredible variety of hybrids that we encounter (geese, ducks, gulls, woodpeckers, warblers, sparrows), which is also due, at least partly, to that aforementioned wonderland. In fact, Colorado’s birders can claim a few first reported occurrences of bird hybrids: Downy × Hairy Woodpecker, Hooded × Yellow Warbler, and American Tree × Harris’s Sparrow. So, what better, here, than hybridizing subspecies?

In this essay, “Yellow-rumped Warbler” refers to the species as a whole, that is, the term includes both subspecies discussed, while “Myrtle” refers solely to the “eastern” subspecies (S. c. coronata) and “Audubon’s” refers solely to the “western” subspecies (S. c. auduboni). I here follow the taxonomic treatment of the species by Pyle (1997), which considers each “subspecies group” to be comprised of just a single subspecies. Both subspecies share the large, well-defined yellow patch on the rump and, when present, yellow patches on the upper sides of the underparts (occasionally erroneously termed “shoulder”), and black streaking on backs of brown (basic plumage) or bluish-gray (alternate plumage; see Leukering 2010 for discussion of plumages). Beware that Magnolia Warbler shares a fair few plumage characters with Yellow-rumped Warbler (particularly Audubon’s), including a yellow rump. However, Magnolia has a smaller, less-obvious yellow rump patch; extensive yellow on the sides; more-extensive streaking below; and, in males, the back is black or extensively so. Finally, due to the difficulty in describing sounds in a textual medium, I treat vo-calizations here only briefly, though acknowledge that the call notes of the two subspecies are easily separable, particularly with experi-ence.

The ProblemBecause both Myrtle and Audubon’s warblers are common and

Scott

Text Box

Note: This is a corrected version of this article. The original article was published online on 30 June 2016; this corrected version was published online on 17 August 2016.


widespread in the state (though with proportions of the two vary-ing from east to west), and because Yellow-rumped Warblers are so distinctive among the family, many birders tend to focus little actual identification effort on them. We hear the distinctively different call notes or see the distinctively different throat colors, make a quick assessment of subspecies, and move on in the search for the next, more-interesting warbler in the flock. However, the main problem that is discussed here is that hybrid Myrtle × Audubon’s Warblers are frequent in Colorado during migration (Figure 1). Given that such hybrids can express virtually any combination or blending of parental plumage characters, a yellow throat does not necessarily an Audubon’s Warbler make.

The SolutionAs for virtually all field-identification problems, the solution is

simply paying more and closer attention, with the various field char-acters firmly in the brain’s forefront. As a basis for detecting hybrid Yellow-rumped Warblers (or Yellow-rumpeds), I provide a synopsis of the many characters that enable differentiation of Myrtle and Audu-bon’s subspecies in Colorado (and most of the rest of the country). As in most taxa in which one can (fairly) easily determine the sexes in the field, discerning the subspecies of adult male Yellow-rumpeds is easier than in immature females, some very drab individuals of which may be impossible to assign without superb, extended, close-range views. For illustration of the following characters delineation, refer to Figures 2–6.

Forehead coloration is blue-gray in most Yellow-rumpeds, though extensively black in at least some male Audubon’s in alternate (breeding; see Leukering 2010) plumage.

The supercilium is typically obvious and white, whitish, or pale buff in Myrtle, but reduced to a more-or-less faint hint immediately above and behind the eye in Audubon’s.

The ear surround, which is the extension of the throat coloration to the back and upward partially behind the auriculars, is white, whitish, or pale buff in Myrtle (though can be nearly absent in some immature females) and absent in Audubon’s.

Throat color is typically white in Myrtle (though see below) and yellow in Audubon’s, with females of both subspecies having this color duller. This character seems often to be the primary (or only?) character used in identifying Yellow-rumpeds to subspecies in the field. In fact, it seems a widespread belief that any Yellow-rumped in the fall without a yellow throat is a Myrtle, when, in fact, many (most?) immature female Audubon’s lack yellow on the throat at that


time (pers. obs., Stephenson and Whittle 2013, Sibley 2014), the throat being a dull buffy color. As some immature female Myrtles sport throat color nearly as dull as this, paying attention to other characters is critical to correct identification of such birds.

The chest color and pattern in alternate-plumaged adult males is nearly solidly black in Audubon’s, while more streaky in Myrtle. In females, the chest is variably streaky, but with Audubon’s perhaps averaging streakier.

The greater coverts are extensively fringed with white in Audu-bon’s, with those fringes so wide on adult males as to create a nearly solid block of white color (then called a “wing panel”). The nar-rower fringes of these feathers on female Audubon’s typically create a “venetian-blind effect” of alternating vertical bands of pale and dark connecting the two wing bars. Myrtle completely lacks obvious white edges to the greater coverts (though they are pale gray), creating two obviously separated wing bars. Juveniles and immatures in formative plumage (see Leukering 2010) of both subspecies sport dull tips (not white) to at least some of the greater and median coverts (the two tracts of feathers forming the wing bars).

Tail spots – By age-sex class, Audubon’s averages more and larger white tail spots than does Myrtle—adults and males having larger and more tail spots than immatures and females. The individual vari-ability in this feature and the general difficulty in counting tail spots makes this character difficult to use. If one gets a chance to both determine the bird’s age/sex class and count individual tail spots, the feature is probably useful, although if one has seen an individual that well, there are probably numerous other characters that would point to the correct identification well before the tail spots are counted. Regardless, those with five tail spots per side are certainly adult male Audubon’s, those with four spots per side are probably Audubon’s, and those with just two per side are probably female Myrtles.

HybridsVocalizations – Though there has been little effort put into ana-

lyzing vocalizations of hybrid Yellow-rumpeds, two points suggest that these may have little usefulness in differentiating between hy-brids and “pure” parental types, except where there is a mismatch between call and plumage. The first is that call notes of most oscine passerines (that is, most everything in an ABA-area field guide af-ter the flycatchers) are thought to be innate, coded on the genes. Presumably, a hybrid could inherit its call notes from either parent, perhaps both. Since we know not whether vocalizations are coded on the same genes as is plumage, it is entirely possible that a virtually


Fig. 1. Distribution in eBird (www.ebird.org) of Myrtle × Audubon’s Warbler hy-brids in Colorado and surrounding area (accessed 27 May 2016). The preponderance of occurrence in eastern Colorado versus that of elsewhere on the map is primarily due to the much greater abundance of birders there relative to elsewhere on the map.

Fig. 2. This alternate-plumaged adult male Myrtle Warbler is typical in exhibiting fairly extensive white on the head—superciliary, ear surround (arrow), and throat—and a streaky chest. Franklin County, Maine, 20 May 2012 (http://ebird.org/ebird/view/checklist?subID=S10802095). Photo by Ian Davies


Fig. 3. This alternate-plumaged adult male Yellow-rumped Warbler shows the characters typical of Audubon’s: dearth of white on the face (lacking a contrasting superciliary and ear surround; compare latter to bird in Figure 1); solid black chest; and large, white wing panel. Chatfield S.P., Douglas County, CO, 27 April 2009. Photo by Loch Kilpatrick

Fig. 4. In basic plumage, the age and sex of Yellow-rumped Warblers, such as this adult male Myrtle Warbler, can be difficult to determine in the field. However, note the bit of gray on the upper scapulars and at the wrist. Particularly note the upper tail coverts, which are mostly black (arrow). Immature Yellow-rumped Warblers ex-hibit only narrow black shaft streaks on otherwise brownish upper tail coverts, while adult females of such show an intermediate pattern. The subspecies is readily deter-mined, with assistance of the known age and sex, by the obvious superciliary (despite its non-white color), noticeable ear surround, and whitish throat. Cape May Point S.P., Cape May County, NJ, 31 October 2010. Photo by Tony Leukering


Fig. 5. This Yellow-rumped Warbler’s dearth of white on the head (excepting eye arcs)

and bright yellow throat, but otherwise dullish plum-

age identify it as a female Audubon’s Warbler. Note

the wide, white fringes to the greater coverts (arrow). San

Diego, San Diego County, CA, 4 April 2014. Photo

by Glenn Giroir

Myrtle-like hybrid could give Audubon’s call notes. The second is that most oscine passerines learn their songs from conspecifics, often from the father, with some apparent genetic basis to the recognition of the song as the one that it should sing (Pettingill 1970, Kroodsma 2005:43). Thus, a hybrid could learn the song of whichever subspe-cies (or hybrid) represented by the male parent.

Appearance – As one might expect, the appearance of hybrid Yellow-rumpeds can vary from virtually Myrtle-like to virtually Audubon’s-like, with only close and extensive scrutiny of some such birds enabling differentiation from parental forms. However, they are not all tricky; some are quite obvious, even to those birders who look only at the throat. In Figures 7–10 (back cover), I present four examples of hybrid Yellow-rumpeds that run much of the gamut of appearance of such birds. Those figure captions provide explanation as to how the birds are determined to be hybrids.AcknowledgmentsI greatly appreciate a thoughtful review of a previous draft of this essay by Ted Floyd.

literAture citedKroodsma, D. 2005. The Singing Life of Birds. Houghton Mifflin Co., New

York, NY.Leukering, T. 2010. Molt and plumage: A primer. Colorado Birds 44:135–

142.Pettingill, O. S., Jr. 1970. Ornithology in Laboratory and Field, 4th ed. Bur-

gess Publishing Co., Minneapolis, MN.


Fig. 7 (back cover). The strong ear surround, streaky chest, and well-separated wing bars on this adult male Yellow-rumped Warbler suggest the Myrtle subspecies. How-ever, note that the supercilium is reduced relative to that of typical Myrtle Warblers and that even a quick glance at this bird’s mix of yellow and white on the throat would enable the determination of this bird as a hybrid Myrtle × Audubon’s Warbler. Flagler S.W.A., Kit Carson County, CO, 27 April 2013. Photo by Steve Mlodinow

Fig. 8 (back cover). With its extensively white throat, streaky chest and, at-least-partial ear surround, this male Yellow-rumped Warbler might readily be identified in the field as a Myrtle Warbler. However, note that the supercilium is nearly absent, there is some yellow in the throat, the ear surround is reduced, and the greater coverts have fairly wide white fringes, all features pointing to the correct identification as a Myrtle × Audubon’s Warbler hybrid. Stulp Farm, Prowers County, CO, 14 April 2016 (http://ebird.org/ebird/view/checklist?subID=S28939674). Photo by Tony Leukering

Fig. 9 (back cover). This yellow-throated Yellow-rumped Warbler might very well be identified as an Audubon’s in the field, but note the extensive supercilium and the sug-gestion of an ear surround on this Myrtle × Audubon’s Warbler hybrid. Longmont, Boulder Co., CO, 20 October 2011. Photo by Steve Mlodinow

Fig. 10 (back cover). This bird’s mostly white throat might suggest Myrtle Warbler to many. However, note the lack of a supercilium, nearly no ear surround, and the bit of yellow on the throat on this Myrtle × Audubon’s Warbler hybrid. Estero San Jose, Baja California Sur, Mexico, 11 January 2016. Photo by Steve Mlodinow

Pyle, P. 1997. Identification Guide to North American Birds, part I. Slate Creek Press, Bolinas, CA.

Sibley, D. A. 2014. The Sibley Guide, 2nd ed. Alfred A. Knopf, New York, NY.Stephenson, T., and S. Whittle. 2013. The Warbler Guide. Princeton Univ. Press, Princ-

eton, NJ.

Tony Leukering, 1 Pindo Palm St. W, Largo, FL 33770 ([email protected])


Fig. 6. Representing about the dullest of plumage of the subspecies, this immature female Audubon’s Warbler has only a suggestion of yellow on the throat and sides. Note also the lack of white on the head, except for the eye arcs and that some im-mature female Myrtle Warblers can approach this appearance, though generally lack the suggestion of yellow on the throat. As the observer noted, “The call note was help-ful!” Boston, Suffolk County, MA, 3 December 2012 (http://ebird.org/ebird/view/checklist?subID=S12212408). Photo by Marshall J. Iliff


Successful Use of a Perch Deterrent to Manipulate Raptor Perchingon Model Power PolesJames F. Dwyer, Michael C. Tincher, Richard E. Harness,Gail E. Kratz

IntroductionAvian electrocution on overhead power lines is an ongoing con-

servation concern globally (Harness et al. 2008, Harness et al. 2013, Martín et al. 2015), throughout the United States (e.g., Dwyer and Mannan 2007, Lehman et al. 2010, Dwyer et al. 2013), and in Colorado (Harness and Wilson 2001, Dwyer et al. 2015, Dwyer et al. 2016a). Concerns range from impacts in specific areas (Harness 2007, Dwyer 2009, Mojica et al. 2009) to population-level effects (Dawson 1988, López-López et al. 2011, Boschoff et al. 2011). Elec-trocutions occur because most overhead power lines are constructed with bare wire to reduce wire cost and weight (APLIC 2006). Power poles (poles) are designed to support specific loads, so reducing wire weight allows greater spacing between poles, reducing the number of poles needed per line, and thus reducing costs for poles and in-stallation. These savings allow lower energy costs for users, but can place birds, particularly raptors, at risk of electrocution when perch-ing on poles. Electrocution (or electric shock injury; Wendell et al. 2002, Dwyer 2009) can occur when a bird simultaneously contacts two conductive components of different electric potential. This can include two energized wires, an energized wire and a grounded wire, or an energized wire and any grounded component. Because birds can safely touch a single wire without risking electrocution, approaches to prevent electrocution focus on preventing birds from contacting two components simultaneously.

Prevention of simultaneous contact can be achieved through cov-ering energized components (Dwyer and Mannan 2007) or through separating components from one another (Harness 2004, APLIC 2006, Harness 2007). Covering energized components prevents birds from contacting them, but in some cases this approach is precluded by pole design parameters (Dwyer et al. 2016a) or does not solve un-related perching concerns (Dwyer and Doloughan 2014, Dwyer et al. 2016b). Separating components can involve framing structures to provide sufficient clearance for at-risk bird species (APLIC 2006, Dwyer et al. 2016a), and is primarily used for new construction or


reconstruction. Separation is usually impractical for existing lines, so perch deterrents are sometimes used to create physical barriers to pre-vent birds from contacting more than one component simultaneously.

Studies of perch deterrents are minimal and inconsistent to date, with some showing positive effects (Slater and Smith 2010, Dwyer and Doloughan 2014) and others not (Lammers and Collopy 2007, Harness and Gombobaatar 2010, Prather and Messmer 2010). Given the sparse and inconsistent evaluation of perch deterrents in the sci-entific literature, and the ongoing use of perch deterrents despite this lack of clarity, we conducted this study to investigate whether perch deterrents might be effective if used judiciously to cover specific elec-trocution risk points.

MethodsWe conducted our study at the Rocky Mountain Raptor Program

(RMRP) in Fort Collins, CO. The RMRP is a raptor rehabilitation facility supported primarily by private donors within Colorado, and through donation of more than 44,000 volunteer hours annually. The RMRP admits approximately 300 injured, sick, or orphaned wild raptors annually. Each admitted bird is evaluated, and if likely to be able to survive in the wild, rehabilitated, and released. Prior

Fig. 1. The flight enclosure contained two model poles, each supporting one 2.4 m (8 ft) long crossarm, three insulators, one conductor cover, and three perch deterrents.


to release, each rehabilitated raptor is placed in a flight enclosure to ensure the bird can fly, maneuver effectively, and hunt live prey. Two flight enclosures at the RMRP include model electric utility poles. These poles do not include any wires or energized components, but serve as a freestanding obstacle raptors maneuver around and perch upon, practicing and demonstrating flight skills prior to release.

To investigate the potential for a perch deterrent to serve as an ef-fective physical barrier between power line components, we modified the existing poles in one flight cage to a C9-1 neutral-down tangent configuration (Fig. 1). A C9-1 tangent pole is designed to support two wires on each side of a 3 m (10 ft) long crossarm (USDA 1983), but is often modified in practice to support two wires on one side of a 2.4 m (8 ft) long crossarm, and only one wire on the other side, with a neutral wire installed below the crossarm (Fig. 2). The wires sup-ported by the crossarm are energized; the wire below the crossarm is not energized. In this configuration, and in the absence of any pole-mounted equipment, electrocution risk typically exists only between the wires on the side of the crossarm supporting two wires.

To evaluate whether we could prevent raptors from perching in this specific risk location, we installed three Preformed Line Products

Fig. 2. On this pole configuration (C9-1 neutral down tangent), avian electrocution risk typically exists only between the two wires together on the same side of the cros-sarm (black arrows).


(Cleveland, OH) BPD-XARM Bird Perch Deterrents between the wires on the two-wire side (Figure 3). Each perch deterrent inter-locked with the adjacent deterrent(s) to form a fence with 20 cm (8 inch) separation between 33 cm (13 inch) tall spikes. Perch deter-rents are sometimes evaluated without additional mitigation mea-sures in place (Lammers and Collopy 2007, Harness and Gombo-baatar 2010, Dwyer and Doloughan 2014), but electric utilities often use combinations of mitigation measures, and previous research has suggested that birds struggling to perch on deterred surfaces may be at increased electrocution risk (Dwyer and Doloughan 2014). Conse-quently, we also installed a Preformed Line Products conductor cover where the center wire would be on a functional pole. We did not include wires on the poles so we could eliminate concerns that rap-tors recovering flight skills might accidentally collide with wires in the confined space of the flight enclosure, potentially undermining rehabilitation efforts.

We quantified perching by introducing raptors to the flight enclo-sure, and then after a 24-hour acclimatization period, we recorded at least 10 perching locations over at least 24 hours. To avoid affect-ing perch locations, RMRP volunteers recorded perch locations from outside the flight enclosure while conducting regular duties (feeding

Fig. 3. Raptors avoided perching between the spikes of the Preformed Line Products (Cleveland, OH) perch deterrents.


raptors, cleaning flight enclosures, etc.). Perch locations were record-ed as “a” through “g” (Figure 4). Staggered data collection over at least 24 hours minimized lack of independence between sequential observations. This approach allowed us to test the null hypothesis that each perch option was used in proportion to surface area avail-ability (insulators 23%, perch deterrents 23%, undeterred crossarm 46%, and pole top 8%) against the alternate hypothesis that perch deterrents were perched on less than their proportional contribution to the total perching surface.

We used compositional analysis (Aebischer et al. 1993, Manly 1997) to test our null hypothesis, ensuring that individual raptors were the sampling unit. Compositional analysis implements a log-ra-tio approach to comparing two sets of data. This approach accommo-dates the unit-sum constraint wherein proportions of use or availabil-ity sum to 1 over all resource types (Aebischer et al. 1993), in this case perch location options. This facilitates comparison of perch events when for any given observation, perching in one place eliminates the possibility of perching somewhere else during the same observa-tion. Compositional analysis may not provide ideal habitat analyses in field studies where available resources are unknown. However, be-cause our resource of interest, perch location on the model poles, was known with certainty, compositional analysis was effective in this

Fig. 4. Perch locations were identified as “a” through “g.”


study. We used the Microsoft Excel tool ComposAnalysis version 5.1 (Smith Ecology Ltd., Monmouthshire, Wales, UK) to conduct com-positional analysis comparing perch location data between used and available locations. We determined the significance of Wilk’s lambda with 1,000 iterations, and substituted a value of 0.01 for zero values in the matrix of perch locations (Aebischer et al. 1993, Manly 1997).

ResultsWe evaluated perching by nine Red-tailed Hawks (Buteo jamai-

censis), six Great-horned Owls (Bubo virginianus), and one Swain-son’s Hawk (Buteo swainsoni) from 27 March 2015 through 20 March 2016. We recorded 175 perching events, including one perching event by one Red-tailed Hawk on the perch deterrent. Across all perching events, 36.6% were on insulators (locations a, c, and g), 0.6% were on perch deterrents (location b), 34.2% were on unde-terred portions of crossarms (locations d and f), and 28.6% were on pole tops (location e). Perch use was disproportional to perch site availability (Λ = 0.27, χ2

2 = 22.10, P < 0.001), with pole tops used the most in proportion to availability, followed by insulators, and un-deterred portions of crossarms. Deterrents were used significantly less than all other perch options, and were used significantly less than expected given their proportional availability.

DiscussionThe Preformed Line Products BPD-XARM Bird Perch Deterrent

was effective in preventing raptors from perching between insula-tors on the two-insulator side of the crossarm. On an energized C9-1 neutral down tangent, this would almost completely eliminate elec-trocution risk. However, numerous other pole configurations exist (USDA 1983, APLIC 2006), including many where deterrents alone may not effectively mitigate risk at all dangerous perch locations. For example, electrocution risk is also associated with the short wires (jumpers) connecting energized equipment to conductors (APLIC 2006, Dwyer et al. 2013, Harness et al. 2013). This risk has not been successfully addressed via perch deterrents. Where pole-mounted equipment exists, perch deterrents may be useful on the crossarm, but should be paired with insulated jumpers and equipment cov-ers (APLIC 2006, Dwyer et al. 2013, Harness et al. 2013). Because equipment covers can be more expensive than perch deterrents, this coordinated approach may simultaneously maximize cost-effective-ness and reduce avian electrocution risk. In another example, perch deterrents installed on poles constructed with grounded metal cros-sarms, or constructed of grounded metal or concrete poles, likely


would not prevent avian perching at all potential points of contact between energized components and paths to ground. In these cases, conductor covers such as the one included on the poles studied here would be needed on all energized wires to fully address avian elec-trocution risks (Cartron et al. 2005, Harness et al. 2013, Servicio Agrícola y Ganadero 2015).

Consistent with APLIC’s (2006) observation that perch deter-rents are intended to shift perching locations, but not entirely pre-vent perching, we found that when only a portion of a crossarm was fitted with deterrents, birds readily perched on the undeterred por-tions of the crossarm. Dwyer and Doloughan (2014) tested perch de-terrents on similar pole configurations to that evaluated here, but did so by covering all potential perching surfaces (crossarm, insulators, and pole-top). Spike-type perch deterrents were most effective at preventing perching (Dwyer and Doloughan 2014). However, when all perching surfaces were fitted with deterrents, electrocution risk was hypothesized to increase because birds intent on perching did so despite the presence of deterrents, potentially increasing contact with pole-top components (Dwyer and Doloughan 2014). This is one of the few consistent findings in studies of avian perch deterrents on poles: when all horizontal surfaces on a pole are covered with perch deterrents, electrocution risk may not be reduced, undermining con-servation efforts.

The spike-type perch deterrent tested here was composed of 33 cm (13 inch) tall spikes spaced 20 cm (8 inches) apart. The spike-type deterrent Dwyer and Doloughan (2014) evaluated was composed of 46 cm (18 inch) tall spikes spaced 10 cm (4 inches) apart. Both were effective. Commercially manufactured spike-type deterrents of alter-native heights and spacing are also available. Future research should compare the relative effectiveness of various spike patterns to iden-tify the most effective parameters, or to identify a range of parameters within which effectiveness is equivalent.

We found that, when installed according to manufacturer’s rec-ommendations, including sizing deterrents to fit the crossarm used, securing the terminal deterrent on each end with a UV-resistant zip tie, and sizing the conductor cover to the insulator used, the deter-rents and covers we tested remained in place as intended. This was true despite almost daily exposure to perching raptors over 12 months of study. Perching on functioning power poles is likely less frequent in most cases, but may be offset by wear related to wind, weather, and solar exposure. The durability we documented in a controlled setting is likely indicative of durability on functioning poles, but should be validated in a field setting.


ACKNOWLEDGMENTSWe thank M. Burns, Preformed Line Products, and Poudre Valley Rural Electric As-sociation for supporting this study. We are also grateful to the volunteers and interns at the Rocky Mountain Raptor Program, without whom this study would not have been possible.

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Harness, R. E., and S. Gombobaatar. 2010. Perch discouragers and raptor electrocutions: Mongolian perspective. In Proceedings: 2010 Southeastern Utility Pole Conference and Tradeshow, Memphis, TN (H. Michael Barnes, Editor). Mississippi State Uni-versity Publication No. 7217-10.

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James F. Dwyer, Fort Collins, CO, [email protected]


On the Importance of Foothills Shrublands to Colorado BirdsJameson F. Chace, Alexander Cruz, Heather Swanson

Often overlooked in the northern, east slope of the Front Range, foothill shrub is squeezed between the expansive grasslands to the east and equally dramatic coniferous forests rising from the plains west to alpine tundra. Foothill shrub is highly variable across western North America in both structure and species composition (Keeley 2000), but all shrubland communities exist in rocky, xeric sites that lack perennial stream flow (Vestal 1917, Armstrong 1992, Benedict 2008). In many areas shrublands can be extensive, such as south of Morrison, Colorado, where Gambel’s oak (Quercus gambelii) is the dominant shrub (Vestal 1917, Keeley 2000, Benedict 2008). Along the Colorado Front Range north of Morrison (Jefferson County), however, foothill shrub communities generally consist of skunkbrush (Rhus trilobata), mountain mahogany (Cercocarpus montanus), choke-cherry (Prunus virginiana), wild plum (P. americana), bitterbrush (Pur-shia tridentata), and hawthorn (Cratageus sp.; Vestal 1917, Armstrong 1992, Cushman et al. 1993). Despite the limited and patchy distribu-tion of foothill shrub along the northern Front Range it is important to a variety of wildlife including ants (Gregg 1963), butterflies (Fer-ris and Brown 1981), reptiles (Hammerson 1982), mammals (Arm-strong 1972, 1992), and birds (Berry and Bock 1998).

Birds have been surveyed and documented in Boulder County, Colorado, since 1909 (Henderson 1909). Based on the extensive, unpublished field notes (1883–1893) and nest collection of Dennis Gale, Henderson (1909), Betts (1913), and Alexander (1937) up-dated the annotated bibliography of the avifauna surrounding the University of Colorado and city of Boulder. With the expansion of the Boulder Open Space and Mountain Parks program in 1973, fur-ther systematic surveys were conducted (e.g., Thompson and Strauch 1987). In a region that has experienced rapid urbanization and an expansion of lower treeline of ponderosa pine into the grassland (Ve-blen and Lorenz 1991, Mast et al. 1997, League and Veblen 2006), there is well-documented population- and community-level impacts on raptors (Berry et al. 1998, Schmidt and Bock 2004), grassland songbirds (Bock et al. 1999, Haire et al. 2000, Jones and Bock 2002), and forests (Chace et al. 2003) of Boulder County. The Berry and Bock (1998) study has been one of the few to explicitly explore the current habitat relationships of the foothill shrub avifauna. Here we


review this rich historical coverage of an often overlooked commu-nity and add our own perspectives.

Focal Area of StudyBoulder County, Colorado, lies at the western edge of the Great

Plains and eastern edge of the Front Range of the Southern Rocky Mountains. Foothill shrublands are rare, comprising approximately 1% of the 188,108 ha of Boulder County, ranging 1,600–2,200 m in elevation. In Boulder Valley since 1897 the average monthly tem-perature has been 10.7°C, with an average daily high of 18°C and low of 3.6°C; average annual precipitation was 46.8 cm (1.1 SE, n = 117 years; NOAA/ESRL, NCAR weather station).

Early checklists of Boulder County birds were published by Hen-derson (1909), Betts (1913), and Alexander (1937), based on field notes, University of Colorado Museum collections and records, and personal observations. A significant contribution was the unpub-lished notes of Dennis Gale (1887 to 1893). The early annotated checklists of Henderson (1909), Betts (1913), and Alexander (1937) describe species as “abundant” (or “very common”), “common,” “un-common” (or “infrequent”), or “rare.” While not specifically limited to, or identified as “shrubland,” these historical notes provide an important benchmark of the Front Range avian community. Three Breeding Bird Atlas I blocks were covered in the lower forests/grass-land ecotone of Boulder County (1987–1994): Eldorado Springs NE, Lyons SE, and Lyons NE (Kingery 1998). While not specific to a single habitat type, the exhaustive coverage of breeding information provides valuable comparative information. Avian surveys (1984–1986) by Thompson and Strauch (1987), an extensive study by Berry and Bock (1998), and our own point count surveys conducted in the foothill shrub west of Boulder (1999–2001) add to growing recent information on avifauna of this community.

We specifically avoided coverage of breeding raptors, nighthawks, swifts, and swallows. These were removed from analysis because the home range size of these far-ranging birds exceeds the patchy distribu-tion of shrubland habitat, even though this community may provide an important habitat component for some species. We recognize the confidence limitations in a qualitative measure of bird abundance over the past 100 years in Boulder County; however, we feel that there is value in attempting to understand avifaunal changes and responses to a changing landscape in this often overlooked bird community.

Species Associated with Foothill Shrublands of Boulder CountyWe report on 23 species commonly found in this habitat. The list


Annotatedbibliography

20-ha plots Point Counts

Breeding Bird Atlas I, Boulder County

(1987–1994)

Species 1909 1913 19371984–1986

1996–1997

1999– 2000 Confirmed Reported

Western Scrub-Jay Aphelocoma californica

1 1 2 0 3 0 2 2

Black-billed Magpie Pica hudsonia 3 3 4 4 4 4 (0.49) 3 3

Rock Wren Salpinctes obsoletus 3 3 3 4 3 1 (0.02) 2 2

House Wren Troglodytes aedon 3 3 3.5 4 3 3 (0.15) 2 2

Blue-gray Gnatcatcher Polioptila caerulea 1 1 1 3 4 2 (0.12) 1 2

Gray Catbird Dumetella carolinensis 3 3 3.5 2 3 0 0 2

Sage Thrasher Oreoscoptes montanus 2 1 2 0 0 0 0 2

Virginia's Warbler Oreothlypis virginiae 3 3 3 4 4 3 (0.30) 1 3

MacGillivray's Warbler Geothlypis tolmiei 2 3 3 3 3 2 (0.07) 0 2

Yellow-breasted Chat Icteria virens 3 3 2 4 4 4 (0.60) 1 2

Green-tailed Towhee Pipilo chlorurus 3 3 3 4 4 3 (0.13) 0 3

Spotted Towhee Pipilo maculatus 4 4 4 4 4 3 (0.13) 3 3

Canyon Towhee Melozone fusca 1 1 1 0 0 0 0 0

Brewer's Sparrow Spizella breweri 1 1 2 3 2 0 0 0

Dark-eyed Junco Junco hyemalis 4 4 4 1 1 3 (0.30) 0 1

Black-headed Grosbeak Pheucticus melanocephalus

2.5 3 3 3 4 4 (0.36) 2 3

Blue Grosbeak Passerina caerulea 1 1 1 2 1 0 0 0

Lazuli Bunting Passerina amoena 3 2 3 4 4 0 2 3

Indigo Bunting Passerina cyanea 0 0 0 1 2 0 0 1

Western Meadowlark Sturnella neglecta 4 4 4 4 4 2 (0.05) 2 3

Brewer's Blackbird Euphaguscyanocephalus

4 3 3 3 1 0 3 3

Common Grackle Quiscalus quiscula 1 1 2 1 2 0 2 3

Brown-headed Cowbird Molothrus ater 3 3 3 4 4 4 (0.36) 1 3

Table 1. Relative abundance of montane shrub bird species in Boulder County, Colo-rado, from 1909 to 2001; 4 = abundant, 3 = common, 2 = uncommon or infre-quent, 1 = rare, 0 = not reported. Relative abundance scores applied to 20-ha plot surveys (n = 8) 1984–1986 (Thomson and Strauch (19v87) and 84 point counts conducted 1996 and 1997 (Berry and Bock 1998). Mean point count results are also reported from 20 point count surveys in Boulder Foothill shrub 1999–2000 (relative abundance). Breeding confirmation from Breeding Bird Atlas blocks (1987–1994) completed in lower foothills of Boulder County (n = 3: Eldorado Springs NE, Lyons SE, Lyons NE).


includes species that are more restricted to foothill shrublands (e.g., Spotted Towhee) and species that also commonly occur in other ad-jacent habitats (e.g., Black-billed Magpie). The probability of find-ing these species provides the serious birdwatcher and ornithologist with a comparative benchmark to examine changes in the Boulder County foothill shrubland avifaunal assemblage (Table 1). The spe-cies most commonly found in foothill shrublands are Black-billed Magpie, Black-headed Grosbeak, Virginia’s Warbler, Yellow-breasted Chat, Dark-eyed Junco (gray-headed form), Lazuli Bunting, Green-tailed Towhee, Spotted Towhee, and Brown-headed Cowbird.

Between 1909 and 2000 the most significant changes in abun-dance occurred among two species that increased and eight species that decreased; the majority exhibited no major change in abun-dance during this time period (Table 1). Increasing species included, most notably, Blue-gray Gnatcatcher (Table 1). Very uncommon in the past and rare today in Boulder County are the Sage Thrasher and Canyon Towhee (Table 1). However, birders taking time to carefully work through the foothill shrublands might be able to document the presence of these two rarities while also further documenting the ex-pansion of the Blue-gray Gnatcatcher.

Blue-gray Gnatcatcher. Observing a Blue-gray Gnatcatcher in Boulder County was noteworthy in the early 1900s (Henderson 1909). Henderson’s 12 May 1905 observation was the singular re-cord until as late as 1937 (Alexander 1937) despite being quite com-mon along the Front Range foothills near Pueblo and farther south. Northward range expansion was documented in Andrews and Right-

er’s (1992) assessment (“lo-cally common to rare in the foothills from Jefferson to Lar-imer County”), which would include Boulder County. Six nests were found between 1993 and 1999 in sparse, low-eleva-tion ponderosa pine savannas (Walsh et al. 1998). According to the Breeding Bird Survey, Blue-gray Gnatcatcher popula-tions have increased annually between 1966 and 2011 sur-vey-wide (0.6%, n = 2,125), in Southern Rockies (3.5%, n = 134), and in Colorado (0.6%, n = 60; Sauer et al. 2012). Re-

Blue-gray Gnatcatcher. Illustration by Alex Cruz Jr.


cent range expansion may be due, at least partially, to fire suppression and the consequent increase of ponderosa pine into declining foot-hill shrub and foothill grasslands (Veblen and Lorenz 1991, Walsh et al. 1998). In the west, gnatcatchers are likely to nest in conifer forests and dense thickets with scattered trees (Barcelo and Faaborg 2012, Kershner and Ellison 2012). Blue-gray Gnatcatcher range expansion is tied to climate change and nesting habitat availability (Kershner and Ellison 2012). Foothills of Boulder County are likely to see an increase of this species, some of which may be nesting in the pine-encroached foothill shrublands (Walsh et al. 1998).

Rare Species of Notable InterestSage Thrasher. A summer breeding resident, although never

common, this species has been observed at the base of the foothills (Henderson 1909, Betts 1913) and at least once over 3,050 m at Cari-bou, 22 July 1933 (Alexander 1937). According to the Breeding Bird Survey, Sage Thrasher populations have decreased between 1966 and 2011 survey-wide (−0.5%, n = 454), in the Southern Rockies (−1.2%, n = 120), and in Colorado (−0.8%, n = 49; Sauer et al. 2012). It was a rare breeder nesting locally along Coal Creek (1987) and in Hall Ranch near Lyons in the 1990s, the same location where a pair was observed by Kingery in 1960 (Hallock and Jones 2010). Sage Thrash-er was detected during the breeding season on two Breeding Bird Atlas blocks near Lyons, but only considered a possible breeder. Sage Thrasher was not detected during any of the more recent surveys re-ported here, consistent with a rare species nesting in a relatively rare vegetation type. Foothill shrub is not a preferred habitat type (Braun et al. 1976); Sage Thrashers in Colorado are largely found west of the Front Range in the intermountain sagebrush (Artemisia) and west slope desert shrub (Kingery 1998). Although fairly tolerant of habi-tat fragmentation (Knick and Rotenberry 1995), Sage Thrashers are eliminated where sagebrush is converted to grasslands (Reynolds and Trost 1980). Their preference for sagebrush makes their recoloniza-tion of Boulder County foothill shrub unlikely. This rare species is infrequently observed during the breeding season, as well as other times of the year, in eastern Boulder County.

Canyon Towhee. A single record in 1895 was reported by Hen-derson (1909) and repeated as the northernmost state record by Betts (1913) and Alexander (1937). Despite available shrub habitat the Canyon Towhee is extremely rare in Boulder County, a situation not likely to change if national decline continues. Canyon Towhee abun-dance has declined during Breeding Bird Surveys between 1966 and 2011: −1.3% (n = 174) survey-wide and −1.6% per year in the South-


ern Rockies (n = 34; Sauer et al. 2012). They still occur rare-ly in Boulder County, with the latest record on 12 July 2011 in shrubby grassland adjacent to the buildings and visitors park-ing lot of City Boulder Open Space and Mountain Parks of-fices in Boulder.

Foothill Shrub CommunityThe foothill shrub avian

community is functionally and structurally composed of five common species that are habitat generalists and a mix of habitat specialists that vary in their relative abundance but

tend to be most common in foothill shrub compared to their abun-dance in adjacent ponderosa pine forests or grasslands. Some spe-cies are more common in adjacent habitats than in shrublands; the foothill shrubland is a minor, but potentially important, component of some breeding populations. This latter group of species includes Black-billed Magpie, American Robin, Dark-eyed Junco, Lazuli Bun-ting, and Brown-headed Cowbird, all of which tend to be omnivo-rous ground foragers (DeGraaf et al. 1985) that can take advantage of available resources in the foothill shrub habitat, perhaps quickly responding numerically when food resources are high (Ostfeld and Keesing 2000). Specialists or species primarily confined to foothill shrub include the Western Scrub-Jay, Virginia’s Warbler, Yellow-breasted Chat, Black-headed Grosbeak, Green-tailed Towhee, Spot-ted Towhee, and Brewer’s Sparrow. These species tend to be insectiv-orous foliage gleaners or ground foragers (DeGraaf et al. 1985), and therefore not especially adapted to foraging in adjacent grasslands, the open understory of the ponderosa pine forest, or among the nee-dle foliage of pine forests. The Western Scrub-Jay is one exception and may possibly be ecologically excluded from adjacent habitats by Steller’s Jay (Cyanocitta stelleri) in the ponderosa pine, and Blue Jay (Cyanocitta cristata) and Black-billed Magpie in riparian habitats. Foothill shrub provides migratory stopover habitat for a number of species, including the Sage Thrasher, as well as potential breeding habitat for some relatively rare species in Boulder County such as the Indigo Bunting and Blue Grosbeak. There are several species in Table

Canyon Towhee. Illustration by Alex Cruz Jr.


1 that primarily use adjacent grassland or forested habitats, but are commonly found in foothill shrub, and therefore we have included, for instance, the Western Meadowlark and Black-billed Magpie. If we were to include all the species that utilize foothill shrub in Boul-der County in part of their breeding home range the list would easily exceed 50 species. This combination of species is a unique assem-blage in Boulder County and representative of foothill shrub com-munities along the Front Range from Morrison north to just north of the Colorado/Wyoming border.

Foothill shrub is naturally patchy and embedded in a landscape mosaic of grassland, ponderosa pine, and linear riparian forests along the east slope foothills of the Front Range. Habitats of the North American west are more naturally fragmented (Franklin et al. 2002) than their anthropogenically fragmented eastern counterparts that have received more attention (George and Dobkin 2002). Bird spe-cies in the foothill shrub have evolved with the patchy distribution of their preferred habitat type, and are capable of utilizing the resources of spatially distributed shrublands as well as the adjacent grassland and forest resources. Adaptation to naturally fragmented habitat does not necessarily pre-adapt a species for anthropogenic fragmentation, however. Some of the same species found in foothills of Boulder County are negatively impacted in shrub habitat that is fragmented by urbanization. For example, Crooks et al. (2004) found that across an urban gradient in the coastal southern California scrub, Spotted Towhee and Lesser Goldfinch were sensitive to urbanization. Evolu-tionary adaptations to patchiness do not provide an ability to evade human commensal predators (Wilcove 1985, Berry and Bock 1998), such as the Common Raven (Corvus corax), American Crow (Cor-vus brachyrhynchos), and brood-parasitic Brown-headed Cowbird that respond positively to urbanization (Crooks et al. 2004). The foothill shrub of Boulder County is in an urban corridor and under threat of residential development, or when protected often is utilized for rec-reation trails. A relatively rare vegetation type along the Front Range of Colorado with a unique assemblage of species deserves greater study and further protection from both residential and recreational development.

Management of Shrub Habitats on Public Land in Boulder CountyMuch of the intact shrubland habitat within Boulder County that

has been protected from residential development is publicly owned by the USDA Forest Service, at higher elevations, and by the Coun-ty and City of Boulder, at lower elevations. Shrubland habitats and the bird communities within them are focal areas for conservation


by these agencies. The importance of these small, isolated habitats is highlighted by the Boulder County Comprehensive Plan (http://www.bouldercounty.org/property/build/pages/bccp.aspx) that in-cludes areas of shrubland in several of the designated critical wildlife habitats. In addition, several shrubland bird species including Indigo Bunting, Lazuli Bunting, Western Scrub-Jay, Sage Thrasher, Virgin-ia’s Warbler, and Brewer’s Sparrow are included as species of special concern.

On county and municipal open space lands, with the threat of development removed, the largest remaining threats to these habi-tats come from fragmentation due to recreational development and loss of habitat through encroachment of conifer forests due to fire suppression. Because of the small, patchy nature of these habitats, they are particularly susceptible to reduction in patch size due to trail development. As a result, in planning for recreational use, land managers work to avoid placing trails through these shrub patches whenever possible. City of Boulder Open Space and Mountain Parks has included the guild of shrub-nesting birds as a conservation tar-get in recent trails planning processes, striving to maintain and con-serve the shrubland habitat. In addition, there is an increased effort to increase public education and interpretive signage explaining the importance of these habitats and the species that live within them. Where trail placement is not able to avoid shrub habitat patches, trails near, but not within, shrub patches allow an opportunity for us-ers to observe and better understand this rare and important habitat and the diverse bird community that lives there. Because of high de-velopment pressure on private land, conservation of this unique and sensitive habitat and associated bird community along the northern Front Range will largely rely on public land management agencies and the support of the public for these efforts.

ACKNOWLEDGMENTSA. Vinton assisted with literature reviews for which we are very thankful. S. Jones pro-vided comments on early drafts and our work benefited tremendously from his in-depth knowledge of Boulder County birds and their habitats. C. Bock provided valuable com-ments on an earlier draft. A. Cruz Jr. graciously supplied the wonderful artwork to ac-company this paper. J. F. Chace was financially supported by Salve Regina University, and greatly appreciates the research support provided by the University of Colorado-Boulder, during his sabbatical. We greatly appreciate the insightful comments by an anonymous reviewer on an earlier draft of the manuscript.

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Jameson F. Chace, Newport, RI, [email protected]


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