audobon state of the birds 2013

7/29/2019 Audobon State of the Birds 2013

1/21

CONNECTICUT STATE OF THE BIRDS 2013

20112013CONNECTICUT STATE OF THE BIRDS

THE SEVENTH HABITAT


2/21

CONNECTICUT STATE OF THE BIRDS 2013 CONNECTICUT STATE OF THE BIRDS 2013

CONNECTICUT AUDUBON SOCIETYThe Connecticut Audubon Society conserves Connecticuts environment through

science-based education and advocacy focused on the states bird populations and theirhabitats. Founded in 1898, Connecticut Audubon Society operates nature facilities inFaireld, Milford, Glastonbury and Pomfret as well as an EcoTravel ofce in Essex andan Environmental Advocacy effort in Hartford. Connecticut Audubon Society manages 19wildlife sanctuaries around the state, preserves over 2,600 acres of open space in Connecticutand educates over 200,000 children and adults annually. Working exclusively in thestate of Connecticut for over 100 years, Connecticut Audubon Society is an independentorganization, not afliated with any national or governmental group. For membership andother information, please visit www.ctaudubon.org.

Connecticut Audubon Society Ofces

STATE HEADQUARTERS2325 Burr Street, Faireld, CT 06824

203-259-6305Hours: Monday-Friday, 9 am-5 pm

CAS ECOTRAVEL30 Plains Rd., PO Box 903, Essex, CT 06426860-767-0660 800-996-8747Hours: Monday-Friday, 9 am-5 pmDirector: Andrew Griswold

Connecticut Audubon SocietyBoard of Directors 2012-2013

Ralph Wood, ChairmanDeirdre Silberstein, Vice Chair

Christina Clayton, SecretaryJoe Mallory, TreasurerWilliam Cotter, Assistant Secretary

Stephen B. Oresman, Chairman EmeritusRobert Martinez, President

Letter From The President

The air column above us is dense with bugs. It forms ashifting mass of protein as important for many b ird species as theplankton of an estuary is for sh. Spiders, beetles, ies, termites,aphids, wasps, midges: they and other organisms populate anaerial habitat that is just starting to be studied.

Many of our most beautiful and thrilling birds, includingBarn Swallows, Common Nighthawks, Eastern Kingbirds,Purple Martins, and Wood Pewees foray into that habitat to feed.Unfortunately, many of those aerial insectivores are declining innumber, some signicantly. Our Connecticut State of the Birds2013 report, The Seventh Habitat and the Decline of Our AerialInsectivores, is an effort to consolidate what we know about thisissue for the general reader interested in conservation.

In our previous seven Connecticut State of the Birds reportswe have assembled and digested well-established research tomake specic recommendations about, for example, protectingforest birds or prioritizing conservation strategies. The dearth ofscientic knowledge on this years subject means those kinds ofrecommendations are harder to make this year. Instead, we intendConnecticut State of the Birds 2013 to be a wake-up call. A seriousproblem exists: aerial insectivores are in critical decline. But thereis not nearly enough research to know for sure why. So lets get down to the serious business ofidentifying the causes and working toward solutions.

The bulk of this year s Actions & Recommendations acknowledge that we need to know moreabout the Seventh Habitat. We are calling for more research and for a greater recognition amongornithologists, entomologists, policy makers, and concerned citizens that the air above us is richwith lifeand that our birds depend on it. We will organize a special conference to bring togetherleaders in the eld for a broader and deeper u nderstanding of the issue. We are calling on the Stateof Connecticut to be a leader in the reduction of the use of harmful pesticides. And we will workwith landowners to manage their habitat so more of our aerial insectivores have places to nest.

As always, we thank our authors for their generous assistance. We hope you nd The SeventhHabitat and the Decline of Aerial Insectivores not just interesting, but worth acting on as well.

Sincerely,

Robert Martinez,President

Robert Martinez

President, Connecticut Audubon Society

CONNECTICUT STATE OF THE BIRDS

David Blagys

Scott Isherwood

Peter Kunkel

Larry Lunden

Judith F. Richardson

Edward Rodenbach

John Salisbury

Thomas Sweeney

Lawrence Walsh

DeVer G. Warner

Benjamin Williams

Connecticut Audubon Society Centers

CAS BIRDCRAFT MUSEUM314 Unquowa Road, Faireld, CT 06824203-259-0416Hours: Tuesday-Friday, 10 am-5 pm

Saturday, Noon-5 pmDirector: Nelson North

CAS COASTAL CENTER AT MILFORD POINT1 Milford Point Road, Milford, CT 06460203-878-7440Hours: Tuesday-Saturday, 10 am-4 pmSunday, Noon-4 pmAssociate Director: Frank Gallo

CAS CENTER AT FAIRFIELD2325 Burr Street, Faireld, CT 06824203-259-6305, ext. 109Hours: Tuesday-Saturday, 9 am-4:30 pmDirector: Nelson North

CAS CENTER AT GLASTONBURY1361 Main StreetGlastonbury, CT 06033-3105860-633-8402Hours: Tuesday-Friday, 1-5 pmSaturday, 10 am-5 pm; Sunday, 1-4 pmDirector: Cindy Bartholomew

CAS GRASSLAND CENTER AT POMFRET

189 Pomfret Street (Rte. 169)

Pomfret Center, CT 06259860-928-4948Hours: Wednesday-Sunday, Noon-4 pmDirector: Sarah Heminway

CAS AT TRAIL WOOD

93 Kenyon Road, Hampton, CT 06247860-928-4948Hours: 168-acre sanctuary open dawn to duskDirector: Sarah Heminway



3/21


CONNECTICUT STATE OF THE BIRDSTHE SEVENTH HABITAT & THE

DECLINE OF OUR AERIAL INSECTIVORES

Table of Contents

Connecticut Audubon SocietyBoard of DirectorsConservation Committee

Scott Isherwood, Chair

Christina Clayton, Co-Chair

Michael Aurelia

Milan G. Bull

Robert Martinez

Stephen B. Oresman

Frederick D. Schroeder

Kathleen Van Der Aue

Connecticut Audubon Society

2325 Burr Street

Faireld, CT 06824

203-259-6305

Connecticut State of the Birds

Editorial Director

Milan G. Bull

Editorial Support

Charles Watson

Graphic Design

Paul J. Fusco

Julian Hough

Photography

Paul J. Fusco

Julian Hough

Printing

Graphic Image, Milford, CT

Acknowledgements

Anthony Vogl, BSA, CT Council

Gina McCarthy, EPA

The Seventh Habitat ........................................................................ 3

Stephen B. Oresman, Chairman Emeritus, CAS

The Mysterious Decline of Aerial Insectivores ........................... 6

Jon D. McCracken, Director of National Programs, Bird Studies Canada

In Thin Air ....................................................................................... 10

Milan G. Bull, CAS Senior Director of Science and Conservation

Thoughts on the Air & the Birds That Make Their Living There ...12

David Ward Winkler, Professor, Ecology and Evolutionary Biology, Cornell

University

Chimney Swifts in Connecticut ................................................... 18

Margaret Rubega, Associate Professor, University of Connecticut, State

Ornithologist

Shannon Kearney-McGee, Avian Population Analyst, Connecticut Department

of Energy and Environmental Protection

Tanner Steeves, Research Assistant, School of Public Health, Yale University

The Purple Martin, A Classic Aerialist ......................................... 22

John Tautin, Executive Director, Purple Martin Conservation Association

Bulbat in the Sky: The Legacy of a Loser? ................................ 26

Wayne R. Petersen, Director of Important Bird Areas, Massachusetts

Audubon Society

Master Aerial Insectiviores: Bats ................................................. 29

Jenny Dickson, Supervising Wildlife Biologist, Connecticut Department of

Energy and Environmental Protection

Recommendations and Observations ........................................ 33

Milan G. Bull, CAS Senior Director of Science and Conservation

Front cover:

Common Nighthawk.

Photo by Julian Hough.

Back cover:

Eastern Kingbird.

Photo by Paul Fusco.

Copyright 2013

Connecticut Audubon Society2325 Burr Street, Fairfeld, CT 06824www.ctaudubon.org


About The Authors

JON McCRACKENhas been studyingbirds since he wasknee-high to aGrasshopper Sparrow.He obtained his honorsBSc in zoology at theUniversity of WesternOntario in 1977. Aftergraduating, he workedas an environmentalconsultant for avariety of Canadiangovernment agencies,non-governmentorganizations, andindustry. In 1989, hejoined the staff of Bird Studies Canada a national non-governmental organization that focuses on the study andconservation of birds. He is the Director of National Programs,and has helped lead the development of a wide variety ofresearch, monitoring, conservation, and educational programslocally, regionally, nationally, and internationally. He is also theco-chair of the national committee that assesses the status ofbirds at risk in Canada.

DAVID WINKLER grew up as a naturalist in the CentralValley of California. After a Bachelors degree in zoology atDavis and a PhD at Berkeley (working on gulls at Mono Lakeunder Frank Pitelka), he did post-docs at the University ofGothenburg (Sweden) and Oxford University (UK) beforecoming to Cornell in1985 as a Lecturer,Post-Doc, and thenprofessor startingin 1988. Ever sincecoming to Ithaca,Winkler has beenstudying Tree Swallowsthere, and these studieshave branched out intocomparative studiesof swallow breedingbiology and movementsthroughout the WesternHemisphere. Accusedrightly of having hishead in the clouds attimes, he has long beenfascinated by the three-dimensional world inhabited by thetiny masters of the air that he studies.

STEPHEN B. ORESMANis a retired managementconsultant, businessexecutive, and corporatedirector. He has a lifelonginterest in birds andconservation starting asa research assistant forthe U.S. Fish and WildlifeService. He is a pastpresident of the ConnecticutOrnithological Association,and is currently chairmanemeritus of the ConnecticutAudubon Society.

MILAN G. BULL is seniordirector of science andconservation for theConnecticut AudubonSociety and is a long-time expedition leader todestinations throughout theAmericas, and to Australia,Antarctica, and Africa. Hehas a BS degree in wildlifemanagement from theUniversity of Connecticutand a MS degree in biologyfrom the University ofBridgeport. He currently isa member of the CitizensAdvisory Council to

Connecticuts Department of Energy and Environmental Protection,and was a founding director and past president of the ConnecticutOrnithological Association. He has also published numerousarticles and speaks statewide on topics relating to ornithology andthe environment. Milan and his wife, Cathy, reside in Faireld.

MARGARET RUBEGA is an associate professor in theDepartment of Ecology and Evolutionary Biology at theUniversity of Connecticut,and is the ConnecticutState Ornithologist. Whileattending Robert E. FitchHigh School in Groton,she spent many hoursat Bluff Point State Parkwhen the adults thoughtshe was elsewhere. Shereceived a BS in Biologyat Southern ConnecticutState University and aPhD from the Universityof California, Irvine. Shestudies structure, function,and mechanics in birds,especially in the matterof how and what they eatand in the context of degrading habitats. Recent projectshave focused on hummingbirds, Monk Parakeets, andChimney Swifts in CT.


4/21


The Seventh HabitatStephen B. Oresman

Chairman Emeritus


About The Authors

The mission of the Connecticut Audubon Societyis the conservation of birds and their habitat.Birdsbecause of our Audubon heritage, and

because birds are colorful, frequently easy to observe,and excellent indicators of the health of our environ-ment. Habitatbecause habitat supports all wildlifestarting with the plants and insects that make up thebase of the food chain all the way up to the top preda-tors.

The initial issues of State of the Birds concentrated

on the six key habitats and the birds that use them innesting, feeding, and migration. These major habitatsare probably familiar to most of us through visits andobservation, and Connecticut Audubon managessanctuaries that contain each of them. They are:

Coastal beaches and offshore islands Tidal salt marshes Shrublands Grasslands Inland wetlands Forests

There is a seventh habitat, however, which nonus have ever walked through and that is probablyleast known and certainly the least studied. Whithe aerial habitat. This habitat has been brought ously to our attention by the work of Canadian sctists who show that aerial insectivores, the birdsfeed in the sky on the wing, are in serious declinefollowing article by Jon D. McCracken of Bird StuCanada has outlined the startling results of this wFor example, the familiar Barn Swallow is now on

endangered list in Canada. The causes of this deare not yet clear.

The Aerial Habitat

But before talking about the birds, we need towhat the aerial habitat is and what it contains. dently it is full of small organisms, mostly tiny arnids (predominantly spiders but also mites, etchas been estimated that a square mile of sky fromfeet to 500 feet contains 32 million arthropods. O

JOHN TAUTIN is executivedirector of the Purple MartinConservation Association.

He is a native ofNorthwestern Pennsylvaniawhere growing up on adairy farm put him in closetouch with the outdoorsand instilled a life-longinterest in wildlife and theenvironment. In 1974 hejoined the US Departmentof Interiors Fish andWildlife Service at Laurel,Maryland, for a career inmigratory bird conservation. During his career, he held a varietyof staff and administrative positions at the Patuxent WildlifeResearch Center and at the Washington, D.C. headquartersofce of the Service. In his last position with Interior, John wasChief of the U.S. Bird Banding Laboratory.

JENNY DICKSON is Supervising Wildlife Biologist at theConnecticut Department of Energy and Environmental Protection.As leader of the DEEPs Wildlife Diversity Program (WDP), shespecializes in songbirds, inland and freshwater wetland birds, andsmall mammals, including bats. She received a BS degree in naturalresource conservation with a specialty in wildlife from the Universityof Connecticut and a MS degree in wildlife management from WestVirginia University. Jenny has also worked as a research biologist forthe federal EnvironmentalProtection Agency on

songbird toxicology and asa naturalist at the KelloggEnvironmental Center inDerby, Connecticut. She hasserved as vice-chair of theNortheast Partners in FlightWorking Group, president ofthe New England Chapterof The Wildlife Society,and is on the executivecommittee of the NortheastBat Working Group.

TANNER STEEVES is a research associate at Yale Universitywith the Vector Ecology Lab where he studies the role of birds,small mammals, and ticks in the natural cycling of humanpathogens. He previously spent several years working with theConnecticut Department ofEnergy and EnvironmentalProtection-Wildlife Divisionwhere he participated ina wide variety of projectsincluding research andmonitoring of raptors, forestbirds, grassland birds, andshrubland birds.

SHANNON KEARNEY-MCGEE is an avianpopulation analyst with the ConnecticutDepartment of Energy andEnvironmental Protection-Wildlife Division. Herprimary focus is researchand monitoring of birdspecies of greatestconservation need.She has initiated manymonitoring and researchprograms focusing onspecies such as woodlandraptors, owls, whip-poor-wills, Chimney Swifts,nighthawks, and shrublandbirds.

WAYNE R. PETERSEN is director of the Massachusetts Important BirdAreas (IBA) Program at the Massachusetts Audubon Society. Among hismany writing projects he is co-author ofBirds of Massachusetts (1993)and co-editor of the Massachusetts Breeding Bird Atlas (2003). He isalso closely associated with the seasonal distribution of New Englandbird life and with the Important Bird Areas of Massachusetts and beyond.Wayne leads international birding tours for Mass Audubon and FieldGuides, Inc. and serves onthe advisory committee ofthe Massachusetts NaturalHeritage and EndangeredSpecies Program and theStellwagen Bank NationalMarine Sanctuary. He wasthe recipient of the AmericanBirding AssociationsLudlow Griscom Award foroutstanding contributions inregional ornithology.


5/21


smaller scale a typical clothes closet of about 10 cubicyards would contain 6.

Milan Bull, Connecticut Audubon Societys SeniorDirector of Science and Conservation, calls this aerialhabitat the invisible habitat. His article (p. 10) de-scribes what is known about the huge number andvarious types of organisms that make it up.

Another term used to describe this biomass in thesky is aerial plankton. Just as the microorganismscalled plankton are the base of the food chain in theoceans, so are the arachnids the plankton of the sky.In his article Dr. David Winkler of Cornell University(p. 12) describes what we know about aerial planktonand the similarities and differences between aerialplankton and the much better known and studiedoceanic plankton.

That the air is full of food is not surprising if youhave ever watched Tree Swallows around their nestboxes. They are constantly in the air swooping and

darting for it seems like hours at a time. They mustbe catching something, as they have plenty of placesto perch and rest and they would not expend all thatenergy ying if they werent catching food. Also, al-though it is now a rarer sight, Common Nighthawksand Chimney Swifts spend the evening hours in con-stant ight high over our cities and towns obviouslyfeeding in the air. Such birds are logically enoughcalled aerial insec-tivores. A completelisting of thosefound in Connecti-cut is displayed inthe centerfold.

Aerial insecti-vores are a particu-larly interesting anddiverse group ofbirds. They includeswallows and swiftsand the CommonNighthawk andWhip-poor-will and

are called Cours-ers, a term thatdescribes how theyfeed. Aerial insecti-vores also includebirds that perch intrees and feed bylaunching forth intothe air. This groupconsists of various

where we disturb them going in and out and they payus back by making a mess of droppings. They alsobuild under bridges and in woodsheds and the like.

The decline of aerial insectivores is not limited toCanada. In Connecticut the Chimney Swift is in seri-ous trouble, as described in the article by Dr. Marga-ret Rubega (p. 8), the Connecticut State Ornithologist.Both the Common Nighthawk and Whip-poor-willare listed under the Connecticut Endangered SpeciesAct. Formerly I saw hundreds of Common Night-hawks every evening in August and early Septem-ber migrating along the shoreline towns in FaireldCounty. They are scarce today. Common Nighthawks

are the topic of the article by Wayne Petersen of Mas-sachusetts Audubon (p. 26), and the article by JohnTautin (p. 22) focuses on Purple Martins.

Bats Are Declining As Well

Then there are the bats. They predominate at nightwhen most of the birds have left the aerial environ-ment. They use the same habitat as the birds andmany of them are threatened as well, suggesting theyare impacted by the same conditions that are causing

ycatchers, including the familiar Eastern Phoebe,and collectively is called Salliers.

An Interesting Peculiarity

Aerial insectivores have an interesting peculiarity.They are more dependent than most birds on man-made structures for nest sites. Purple Martins are to-tally dependent on martin houses put up by humans.Chimney Swifts not surprisingly prefer chimneys.Barn Swallows and Cliff Swallows nest on barns andbridges, and if you have Bluebird boxes you knowthat Tree Swallows will frequently beat the Bluebirdsto them. Finally Common Nighthawks like to nest onat roofs of buildings.

One wonders where these birds nested before theyused human structures. Were Chimney Swifts lesscommon before chimneys and Barn Swallows rarerbefore barns with open sides or broken windows?This is an ancient and worldwide behavior pattern.The Common Swift of Europe has nested in the West-ern Wall of the Temple Mount in Jerusalem since thebeginning of recorded history.

Even the ycatchers, which tend to nest in forests,have one species that likes human habitations. TheEastern Phoebe will nest almost anywhere. Many ofus have had them nest on a pillar by the back door

the decline in birds. The decline of some specibats, however, has been linked to disease. Thereight species of bats in Connecticut. The trend inpopulations is described in an article by Jenny Dson of the Connecticut Department of Energy andvironmental Protection (p. X).

So what is the problem with the aerial habitatthe aerial plankton biomass? And what is goinwith the tiny insects above our heads and the band bats that feed upon them? There are a numbhypotheses, including acid rain and increased upesticides. We can also see when a forest is fragmed or a tidal marsh lled, but what is happening

the tiny insects above our heads and the birdsbats that feed on them? Clearly these are areas wstill more research is needed. But along with sucsearch, we also urge specic actions by governmbodies and by individuals on their own propeSee the recommendation section (p. X) for detaiwhat needs to be done.

* * * * * *

Barn Swallows depend on manmade structures for nest sites.

Chimney Swifts feed high in the air column.

JULIANHOUGH


6/21


The Mysterious Decline of AerialInsectivores

Jon D. McCracken,

Director of National Programs

Bird Studies Canada

Mysterious, in-e x p l i c a b l e ,strange, and

alarming. Terms likethese are increasinglybeing used to describethe declines of popula-

tions of nightjars, swifts,and swallows (plus anumber of ycatchers)across large parts of theUnited States and Can-ada. These birds repre-sent the aerial insecti-vore feeding guildtheone that specializes in adiet of ying insects.

The declines areshowing up in long-term monitoring pro-grams like the NorthAmerican Breeding BirdSurvey, and are rein-forced by results frombreeding bird atlas projects that have been repeated ina number of states and provinces. Species like Com-mon Nighthawk, Eastern Whip-poor-will, ChimneySwift, Barn Swallow, Bank Swallow, and Olive-sidedFlycatcher are facing particular difculties. Some ofthem have experienced population losses of over 90%

since 1966 in eastern North America.If you live in the Northeast, the situation is gen-erally worse than elsewhere. A recent study foundthat aerial insectivore declines across North Americagenerally follow both a latitudinal and longitudinalgradient, such that they tend to be stronger in theNorth than the South, and greater in the East than inthe West. They are also most pronounced for long-distance migrants that winter in South America. Anin-depth examination of these geographic patterns

could reveal important clues into the underlyingcauses of the declines.

Looking for the Trigger

The mechanisms responsible for the declines arenot known, but several factors are likely acting to-

gether. Some are undoubtedly affecting certain spe-cies more than others. For example, reduced availabil-ity of particular kinds of articial nesting substrates(e.g., open chimneys, open wooden barns, and gravelrooftops) helps explain, at least in part, declines of afew species like Chimney Swift, Barn Swallow, andperhaps Common Nighthawk. However, we also seelosses occurring in species that should be protingfrom increased provisioning of nest boxes (e.g., TreeSwallow and Purple Martin).

We also know that large acreages of abandonedmarginal farmland (especially pastures and hay-elds) in many parts of eastern Canada and thenortheastern U.S. have been reverting to forest coversince at least the 1950s. This has resulted in the lossof open-country foraging habitat that several aerialinsectivores are strongly associated with. However,it again cannot explain population declines of forest-dwelling birds like Eastern Wood-Pewee and EasternWhip-poor-will. Nor does it explain why some open-country (non-aerial) specialists like Eastern Bluebirdare faring so well.

One cannot escape the fact that the single trait thatthis otherwise disparate group of birds shares is areliance on ying insects during all or most of theirlife-cycle. Largely unseen by us, a whole ecosphere ofwhat is essentially aerial plankton is ying in theairspace above us. We see only a tiny fraction of thisinsect life as it buzzes around our heads or visits our

owers. Far greater numbers are yingor merelydrifting or ballooning on air currentshundredsand even thousands of feet overhead.

Aerial insectivores exploit this rich food supplyto various extents. Some like swallows, swifts, andnighthawks are better adapted for foraging at higher

altitudes than ycatchers and Eastern Whip-pwills, which sally from hunting perches. Somecies in the guild, most notably several of the ycers, are also able to supplement their diet with otypes of food, including terrestrial insects, berand seeds.

Exceptionally little is known about the poption status of ying insects in North America. Wwe do know is that bird populations can and dspond quickly to changes in the abundance of food supplies. So its not unreasonable to suspectaerial insectivores are declining, at least in part,result of some change in food supply at one or mpoints in their annual life-cyclewhether its on breeding grounds, wintering grounds, along theigration routes, or all three.

Changes in insect availability could be happeon more than one front. It could be that the ovabundance of ying insects is falling, perhaps as

sult of decades of intensive, wide-scale insect coprograms associated with agriculture and forestrperhaps there are subtle shifts taking place in thesonal timing of insect emergence as a consequenclimate change. Even minor mismatches in the timof seasonal cycles of birds and their insect prey

Northeast Population Trends of Aerial Insectivores

In eastern North America, Whip-poor-wills have declined nearly 90% since 1966.

PAULJ.

FUSCO

Courtesy: North American Bird Conservation Initiative Canada


7/21


all ying insects have either a terres-trial life stage (e.g., as a caterpillar)or an aquatic one (e.g., mosquito lar-vae). If the sheer abundance of all y-ing insects were declining everywhereacross the board, then one would ex-pect that bird species that eat thembefore they go airborne would also beexperiencing widespread patterns ofdecline. But this isnt the case. Thereare many examples of non-aerial spe-cies of insectivorous birds increasingin abundance. This discrepancy alsocalls into question the seasonal food

supply mismatch hypothesis.Other potential causes of the decline of aerial in-

sectivores include exposure to environmental con-taminants such as mercury and pesticides, which cannegatively affect birds longevity and reproductiveoutput. Reduced availability of calcium, which is alegacy consequence of acid rain, could also be impli-cated. A good source of dietary calcium is essentialduring the breeding season to optimize egg produc-tion and for bone development of young birds.

Several other hypotheses have been suggested.Every smoking gun has a trigger, but this one seemsparticularly elusive.

Research Priorities

Because declines tendto be greatest in Canadawhere I live, gaining arm understanding of theproblem faced by aerialinsectivores is emergingas a top research priorityhere. Interest is also catch-ing on in the northeasternU.S., particularly for goat-suckers and swifts. So far,two scientic workshopshave been convened inCanada to begin to iden-tify the highest-priorityresearch topics.

The questions are not

only large and complex,but the geography in-volved is even more ex-pansive. Answers are most likely going to come fromthe creation of international collaborative networksof scientists, who team up together to focus on one ormore research questions.

Basic population ecology is going to underpin theresearch agenda. For any species, population declinesare ultimately driven by increased mortality rates orfalling reproductive rates, and sometimes both. Sofar, we simply do not know whether any of these ba-sic demographic measures have been changing overtime for any aerial insectivore, even for well-studiedspecies like the Tree Swallow.

Also high on the to-do list is to gather much bet-ter information on what aerial insectivores are do-ing during the non-breeding period, what habitatsthey require, and what threats they face away fromthe breeding grounds. For long-distance migrants,we have only a vague understanding of where theyspend their winters in South America, let alonethe routes they take to get there and back. Some ofthese questions are just starting to be cracked open

through the use of new technologies that allow bi-ologists to track the whereabouts of birds over thecourse of a year.

Using tiny light-sensitive gizmos called geoloca-tors, a collaborative team led by Dr. Bridget Stutch-bury (York University in Toronto) has been gatheringimportant new information on Purple Martin migra-tion routes and identication and use of their tropi-cal wintering areas. A similar international collabora-tive will soon start yielding results on Tree Swallows,

while another has begun on Eastern Whip-poor-wMany more of these types of studies are badly neefor other species of interest.

What Does the Future Hold?

In Canada, Chimney Swift, Eastern Whip-pwill, Common Nighthawk, Olive-sided Flycatcand Barn Swallow have all been recently assesseThreatened species owing to severe populationclines. More aerial insectivores can be expected tadded to Canadas list of species at risk. Evaluatare already underway for Eastern Wood-PeweeBank Swallow. Black Swift will also be assessed shly, and Eastern Kingbird is emerging as a prioritfuture evaluation.

Because most aerial insectivores are still comand have large breeding ranges, the chances of anthem becoming extinct in the next couple of decseem quite remote. We still have time to gureout. Thats the good news.

The bad news is that unless rates of declinehalted or reversed in a timely way, total populacollapse eventually becomes something of a mematical certainty. Even more worrisome are thefound sociological and economical implicationsmight be facing us if it turns out t hat declines of ainsectivores are being driven by changes happeto populations of ying insects.

* * * * * *

Possible Causes For Decline: Reducedavailabilityofman-madenesting

sites(barns,openchimneys,gravelrooftops)

Lossofopen-countryforaginghabitat Changesininsectavailability Exposuretoenvironmentalcontaminants

Reducedavailabilityofcalcium,aconsequenceofacidrain

Mayies provide an important food source for insectivores.

been shown to have important implications for birdsurvivorship and nesting productivity. This is partic-

ularly true in the spring in northern latitudes, whenenergy demands for insect-eating birds can be highlysensitive to swings in temperature. It is well knownthat an ill-timed cold-snap in the spring can lead tomass starvation of swallows and martins.

Some Puzzling Anomalies

As intriguing as some of these possibilities are,there are also aspects that make you scratch yourhead. For one thing, before they become airborne,

The Eastern Kingbird is a priority for future evaluation.

JIMCONRAD


8/21


In Thin AirMilan G. Bull

Senior Director of Science and Conservation


Coursing the air almost be-yond the reach of vision,small parties of Chimney

Swifts are obviously on a feedingmission, but what are they feed-ing on up there? Swallows, night-hawks, and other birds also seinethe sky for largely unseen insectfood. There are feeding strategiesamong the bird species employed

here as well. Swifts and night-hawks are feeding in the upper lay-ers, sometimes 400 feet high andhigher, while Barn Swallows skimthe surfaces of lakes and meadows.Whatever the composition of thefood source, it seems invisible to uson the ground. In fact, although thesky appears transparent, we are ac-tually sitting beneath an enormousmass of animals, day and nighta biomass cloud thatwe are just beginning to understand and appreciate.

We began to look more closely at this phenom-enon when we learned that nearly all birds that feedonly on ying insects are declining, and althoughthere may be countless factors involved here, theone that cannot be overlooked is the food source.What this biomass contains, how it moves, and whatfactors inuence it have been subjects of discussionfor decades.

An Astonishing Number Of Insects

In 1926, P. A. Glick and his colleagues at the U.S.

Bureau of Entomology and Plant Quarantine be-gan collecting insects by airplane using sticky trapsbeneath the planes wing. Over the next ve years,the researchers ew thousands of trips over Louisi-ana and collected tens of thousands of insects at al-titudes up to 15,000 feet. They were astounded bythe enormous numbers of insects they discovered aswell as the heights at which they found them. Theyestimated that at any given time on any given dayof the year, the air column rising above one square

mile of Louisiana countryside contained an averageof 25 million insects and perhaps as many as 36 mil-lion. Later, Dr. Gilbert Waldbauer, Professor Emeritusof Entomology at the University of Illinois, estimatedthat during the daylight in May, a volume of air onemile square extending from 20 feet above the groundto an altitude of 500 feet contained 32 million arthro-pods. He said that This amounts to 6 arthropods per10 cubic yards of air. Ten cubic yards is quite a smallspace, about the size of a small clothes closet. Wald-bauer also noted that the aerial plankton at night areonly about half as numerous as those during the day.

In January 2006, a mass mortality of a species of

ground beetle,Mecodema curvidens, resulted in a largeocean beach drift on the southern Atlantic Coast ofBrazil. The dead insects piled up along nine miles ofshoreline at an average of about one foot in width.This amounted to a conservative estimate of 18 mil-lion insects!

The presence of this aerial phenomenon had beenobserved for years. Charles Darwin, during his fa-mous voyage on the Beagle, was astonished at a massof ballooning spiders that parachuted onto the deck

of the ship when it was over 90 miles from shore. Withadvanced radar technology, we are now beginning tounderstand the size and complexity of this biomassand the way it moves around the planet. What wedont know yet is how it affects our aerial insecti-vores: the swifts, swallows, and other b irds that forayinto it for food.

The Aerial Biomass Is Huge

Dr. Jason Chapman and his group of researchersat the Plant and Invertebrate Ecology Department atRothamsted Research in Britain are among the lead-ers in this study of aerial plankton. Chapman has beenusing advanced radar technology to study the com-plexity of this biomass. He found that many insectsundertake long-range seasonal migrations to tempo-rary breeding sites that are hundreds or thousands ofkilometers apart. How they adapted behaviorally toaccomplish this is unknown. They also found that theability to select the correct high-altitude winds at theright season is widespread among large day-ying(and night-ying) insects and that insects even takeight headings that partially correct for crosswinddrift! These ight behaviors match the sophistica-tion of those seen in migrating birds and help explainhow high-ying insects migrate successfully betweenseasonal habitats. Chapman also concludes that thisaerial biomass is huge. Using radar, the scientistscalculated that if you add up all the insects passingabove you in a .6 mile column of air during a typicalspring and summer month, it would add up to overthree billion insects!

In the U.S., the study of aerialplankton is ramping up. Dr. Thom-as Kunz, professor of biology anddirector of the Center of Ecologyand Conservation Biology at Bos-ton University, has introduced anew discipline called Aerioecology,which focuses on the aerosphereand the biomass of organisms thatinhabit and depend on this environ-

ment for their existence. The newdiscipline combines atmosphericscience, geography, ecology, andcomputational science in ways thateven its pioneers could not havepredicted. Technological advancesthat now allow meteorologists tocount the raindrops in a cloud areopening new windows into our un-derstanding of the aerial biomass.

What is the composition of this biomass? Sies have identied hundreds of species in the aplankton. Butteries and ies have been founaltitudes of 5,000 feet; aphids, wasps, midges,beetles at 6,000 feet; spiders at 12-14,000 feet; atermite at 19,000 feet. Dr. Jerome Rovner, a leaarachnologist (authority on spiders) at Ohio versity, observes that Ballooning spiders inmake up a large component of the aerial planktAs Darwin noted, many spiders are known to loon. They extend strands of silk into the airare caught in the wind, carrying the spider up the atmosphere and away on the wind currents. Mballooning spiders are immatures, but why do balloon? Studies have indicated that food shoes and overcrowding stimulate aerial dispersalother environmental factors may also be at play.

The fact that spiders and other insects, driveintercontinental winds, are drifting in the atmosp

at more than 12,000 feet has implications for gwarming, changing wind and weather patterns,invasive speciesindeed, a whole host of factorsmay be inuencing all aerial insectivores.

Understanding this ecosystem and the intertionships of arthropods, birds, and bats that useaerosphere will be important for bird conservabut also for maintaining biodiversity, human heand the environmental health of our planet.

* * * * * *

Many species of birds feed exclusively on ying insects.

Ballooning spiders are an important component of the aerial biomass.

JOSEFMOHYLA


9/21

CONNECTICUT STATE OF THE BIRDS 2013 CONNECTICUT STATE OF THE BIRDS 2013 112

Thoughts on the Air and the BirdsThat Make Their Living There

David Ward Winkler

Professor, Ecology and Evolutionary Biology

Cornell University

The growing ac-knowledgmentthat populations

of aerial insectivorousbirds in the northeast-ern U.S. and southeast-ern Canada are declin-

ing has caused us toreect on all aspects ofthe biology of this fas-cinating guild of birds.One of the aspects oftheir biology that hasmost fascinated manyis the habitat they livein. Of course, all y-ing birds live in the airevery time they takeight. But in this essayI will concentrate onthe most aerial of birds,the aerial coursers.

These are the birdsthat make their liv-ing in the air almostfull time, the birds that feed on the wing in long sus-tained ights that can last many hours or even days.Birds like ycatchers certainly foray into the air everytime they y after a passing insect, but they are veryseldom more than a few meters above the Earth, asthey always return to their perch between foragingattempts. In contrast, swifts and swallows (and lessfamiliar birds like them elsewhere) spend most oftheir lives in the air, plying the waves of air above andaround us just as storm-petrels make their way acrossthe oceans of water. And storm-petrels resembleswallows more than in their graceful mode of travers-ing their realms: they are both planktivores of sorts.Swallows grasp small insects from the air and storm-petrels grasp small invertebrates from the water sur-face. The prey of both birds are plankton, meaning

that the movements of the tiny prey are ruled moreby the movements of the medium in which they livethan by the results of their own exertions. Thus, tounderstand the distribution and variability of theirfood, we need to understand the movements of water

versus air.Water Versus Air

Water is perhaps the most quintessential substanceof Earth. No single rock type distinguishes Earth aswell as does the abundance of water in all three ofits physical forms: vapor, liquid, and solid. Of these,liquid water is what makes ours the blue planet,and its properties dominate the conditions for life onEarth. The cycling of its temperatures and densities

in a temperate lake is emblematic of its tremendousphysical constancy and the relative predictability ofits behavior: in summer a layer of warm, light wa-ter, often only a few meters deep, oats on top of adeeper, colder layer with a temperature of about fourdegrees Centigrade. The light, warm water on topis remarkably stable. Even with considerable wind,although the upper layer may slosh back and forthacross the lake basin in slow, low waves, it still re-mains stratied atop the colder and heavier deep wa-ters. This thermal stratication lasts all summer andeventually erodes into a fully mixing lake only afterthe bright sunshine and heat of summer are replacedby the dark, cold winds of fall and winter.

This unusual stability and predictability standin stark contrast to the behavior of air. Air is almostoutside our experience. We speak of things vanishinginto thin air, and we spend much of each day forget-ting that the air exists. But as soon as we open thewindow in a rushing car, or we cower in the housewhen a powerful thunderstorm with its strong localwinds rolls past, we are reminded that air is viscouslike water, just less so. One of the wonders of Earthis that air has sufcient viscosity that tremendous

pressure differences can arise over very short distespressure differences that can produce tornaand hurricanes and typhoons. Anyone who has lthrough one of these disastrous phenomena will er accept that the air is insubstantial!

Air follows all the same rules of uid mecics as does water, but everything about air is mmore changeable. Even when it is not up to somits more spectacular manifestations of viscosity, tare many signs of its ever-changing currents anddients. In summer, a dandelion seed or scrap oflophane can serve as a reliable indicator of the toous currents otherwise hidden in a bright summsky. And when air is moving at the surface, it is g

to look farther skyward, as clouds often give usbest indicator of conditions aloft. On sunny days puffy cumulus clouds popping up in the afternone can be sure that there is a good deal of vermovement of air, as it is vertical convective cells ofrom lower levels that bring water vapor to the ulayers, where it condenses into water droplets clouds. As vertical movement grows stronger, mvapor is taken farther faster; and when the solarergy being poured into the system is strong enou

Wilsons Storm-petrels feed on oceanic plankton.

Tree Swallows seine aerial plankton.

JULIANHOUGH


10/21


water vapor can be carried many thousands of feetinto the cumulonimbus clouds that are one mark ofsevere thunderstorms. In thunderstorms, the con-vective cells often engender strong lateral winds atthe ground, feeding the rising air column, and largenumbers of insects can be concentrated and carriedfar aloft, where swifts and swallows sometimes ag-gregate at altitudes, much higher than is their wont,to feed on concentrated and cold-stunned prey.

Thefundamentalmismatchinthewaysthatinsectsandbirdsadjusttheirlifehistoriestotheirenvironmentshasledsometofearthatanothersortofmismatchmaybeaffectingaerialinsectivorousbirds in the Northeast.

given day. Thus it is notuncommon in a northernspring for aerial insec-tivores to go overnight,with the simple arrival ofa cold front, from a feastof available insects to afamine. This rapid alter-nation in available preycan have large effectson breeding productiv-ity if a cold snap lasts acouple of days or more,and the generally highbreeding productivity ofswallows can be slashedto large-scale failure ifsuch conditions ariseduring the time of chick

development when theirfeeding requirements arehighest.

The Price OfBeing Warm-Blooded

It is a price of being a warm-blooded animal thatones metabolic requirements remain high no matterwhat the weather. Insects can go on ice when it istoo cold to y, but birds must continue to feed theirmetabolic res to keep their temperatures high. Thisdifference between homoeothermic and ectothermicanimals helps explain an interesting difference in thetiming of annual cycles of abundance and activity ininsects and birds around the northern hemisphere:insects respond exibly to changes in weather andclimate, whereas vertebrates take longer to adjust thesettings on their programs of self-regulation. Theseslower adjustments can lead to mismatches in breed-ing schedules and food availability, causing birds toattempt to breed in spring after peaks in food abun-dance have already passed.

This fundamental mismatch in the environmental

adjustments of insects and birds has led some to fearthat another sort of mismatch may be affecting aerialinsectivorous birds in the Northeast. It may be thatinsects across the board are responding to warmersprings and summers in the North by shifting theiremergence earlier in the year, thus reducing the avail-ability of aerial insects in late summer and early fall,just when aerial insectivores need high quantities offood to fuel molt and migration. This mismatch couldexplain declines in aerial insectivores of diverse mi-

gratory schedules and destinations across the Noeast, but it would not answer why aerial insects mbe affected differently than the foliage-bound inon which the bulk of other migrant birds rely.

of air as a habitat forcoursing insectivores:that available insectdensities drop off steep-ly with altitude. Thusit is not too surprisingthat most aerial insec-tivores spend most oftheir time foraging inthe rst tens of metersabove the Earth. Andwithin that band, thereappears to be a looseapportionment of for-aging space, at leastamong North Americanswallows: Barn Swal-lows most often nearthe ground, Tree and

Rough-winged at mid-level, then Bank gener-ally higher, and Purple

Martins up at the highest levels, often with swiftsand nighthawks. This stratication raises the ques-tion of what may be taking such high-foraging birdsso high. If food densities are generally much lower athigher altitudes, are these birds taking larger prey tocompensate for the lower prey densities where theyforage? Do the high iers have any special sensory orcognitive skills that allow them to nd and capturelarger prey more efciently?

Air Temperatures Change Rapidly

The other interesting thing about air versus wateris the relative rapidity with which air temperaturescan change, and many of the most rapid changescome about through the displacement of large massesof air. Temperatures can drop dramatically overnightwith the arrival of a cold front from the north, andthese changes in air temperature contrast with thosein water, the high thermal inertia of which helps buf-fer lakes and rivers from large daily swings (and of

course water has a hard time moving out of lake ba-sins the way air can shift over the Earths surface!).Many aerial insects hatch out from aquatic habitats,and they may thus emerge from water warm enoughto support their eclosion into air that is too cold to al-low them to y. Different insects have very differentthermal optima for ight, and aerial insectivores aresubject to dramatic changes in available food from oneday to the next, depending on what groups of adultinsects are present and on the air temperatures on any

Aerial insectivores are adept at catching ying insects.

Many insect species have an aquatic lifestage.

JULIANHOUGH

Thus, currents in the air can be just as strong asany currents in water, and we have a great deal tolearn about how currents in less extreme conditionsthan thunderstorms may affect the foraging behaviorand ecology of aerial insectivorous birds.

We do know a couple of interesting things, though.First, those big concentrations of insects in the air as-sociated with high altitudes in thunderstorms aremajor exceptions to one of the known properties

Insectsrespondmoreexiblytochangesinweatherandclimate.Vertebrates take longer to adjust.

If aerial and foliage-associated insects respdifferently to climate change, one of the rst pto look for an explanation would be in their envments. Both insects and birds living in these habmust cope with different gradients with diffdynamics, and we are only beginning to underswhat some of the key differences might be. We k

that air, like land and water, is rich in heterogenand the rates at which airs heterogeneity changemuch faster than in the other two environs. We arbeginning to sift through the implications of thesferences, and, as we begin to do so, we will no dgain a much more synthetic understanding ofmost continuous and pervasive habitat on Earth.

* * * * * *


11/21


AERIALINSECTIVORES

CONNECTICUTS

Tree Swallow

Chimney Swift

Bank Swallow

Common Night

Northern Rough

Swallow

Purple Martin

Barn Swallow

Cliff Swallow



12/21


Chimney Swifts in ConnecticutMargaret RubegaAssociate Professor, University of Connecticut

Shannon Kearney-McGeeAvian Population Analyst, Connecticut Department of Energy andEnvironmental Protection, Wildlife Division

Tanner SteevesResearch Assistant, School of Public Health, Yale University

In the marketplace of what makes a bird attractiveto people, a Chimney Swift (Chaetura pelagica) haslittle capital. It isnt colorfulthe bird is a nearly

uniform sooty brown all over. It isnt melodicthevocalizations amount to a kind of monotonous twit-

tering, pleasant enough but any kid with a blade ofgrass and two thumbs could sing as well. It isntbigit weighs less than a quarter of what your i-Phone does. It wont come to your bird feeders, sitsnowhere that you can photograph it, and glues itsnest together with spit.

Yet a little attention will show that ChimneySwifts are marvelous things. For pure aerobaticspeed and skill in ight, they are exceeded only bytheir nearest relatives, the hummingbirds, and theyare much more visible, if you only look up. Theyare frequently described as looking like a cigar withwings, but they are more often mistaken for swal-lows, from which their unforked tail and scythe-shaped wings can distinguish them. A ChimneySwift eats hundreds of insects a day, taken only outof the air while ying at high speed. If this seemsunimpressive to you, imagine catching airborneM&Ms, without your hands, on a 35-mile-an-hourdrive-by. They are everywhere in Connecticut wherethere are chimneyswhich is to say, just about ev-erywhere. They are arguably more emblematic ofbird life in Connecticut than any other species, evenour ofcial state bird, the American Robin. They not

only live closer to us, although often unnoticed, theyare downright dependent upon us in a way that noother bird is.

Europeans Might Have Called ThemTree Swifts

If Europeans had been paying more attentionwhen they rst arrived in North America, theymight have called them tree swifts, because the

missing from Connecticut; in fact, tak-ing into account year to year variation,the size of Connecticuts Chimney Swiftpopulation is apparently stable (Figure2). But since birds are no respecters ofstate boundaries, a declining populationanywhere is a message about the healthof populations everywhere. Consequent-ly, counting about the same number ofbirds in the air every year in Connecti-cut doesnt demonstrate that the overallpopulation is healthy. Connecticut mightindeed be very hospitable to ChimneySwifts; alternatively, it might be a sink,an area where birds die or fail to breed ev-ery year but the total number of birds re-mains the same because birds continue tomove in from surrounding areas. We sim-ply dont know. In order to nd out, we

need to understand how birds are usingthe habitat and whether they are breed-ing successfully. If wildlife managers inConnecticut want to keep common birdscommon, they need to think about whyall those swifts have disappeared, beforethey become endangered anywhere.

Are There Fewer Chimneys?

It is very common when bird popula-tions decline to nd that the kind of habi-tat they like to live in has disappeared too.There certainly are not fewer buildingsthan there were 40 years ago! Of course,the birds are not nesting in living rooms,shopping malls, or ofce towerstheynest in chimneys. Are there fewer chim-neys? New construction typically no lon-ger includes the classic open-u brick de-sign; small-diameter pipe vents are far more energyefcient. Even the older style of chimney is not a surebet. A chimney that has been capped and screenedoff, or lined with a metal ue-duct, is still a chimney,

but it is no longer Chimney Swift habitat.All over North America, avian conservation or-

ganizations and wildlife agencies concerned withChimney Swift population declines have naturallyfocused on the availability of chimneys. For instance,Rua Mordecai, a U.S. Fish and Wildlife Service bi-ologist monitoring swifts in North Carolina, hasdocumented that many chimneys formerly occupiedby swifts have been lost to capping. There is wide-spread interest in building freestanding chimneys

(sometimes called swift towers) to replace tlost to capping and lining, such as the tower reccompleted at Stamfords Cove Island SanctuaryUniversity of Connecticuts Ornithology Rese

Group, with support from the Department of Enand Environmental Protection, set out four yearsto develop a swift tower design which was easierless expensive to build than the design widely by sanctuaries. We aimed to make a swift towercould be built rapidly by anyone with hand toolsthat was low-maintenance, moveable, and attrato swifts. We envisioned Boy Scout troops acrosland, replacing habitat for swifts the same way did for bluebirds. We built 10 towers of a design

PartnersinFlightestimatesthatthereare15millionChimneySwiftsinNorthAmericabutclassiesthemascommonspeciesindeepdecline.

birds originally nested inside hollow old-growthtrees. Exquisitely adapted for life in the vertical, theycant perch on a horizontal surface but can hang onan upright one, where their protein-enriched saliva isused to glue twigs into a shelf-like structure in which

they lay their eggs and tend the resulting chicks. Dur-ing the settlement of New England, as the trees camedown and the buildings went up, the birds simply be-gan using the hollow, vertical brick-and-stone struc-tures newly scattered over the landscape instead ofthe disappearing trees. There is some evidence thattheir range actually increased, spreading with thebuildings into landscapes previously too unforestedto support them.

Chimney Swifts prefer to nest in open-u, brick chimneys.If buildings were all it took to build a populationof Chimney Swifts, one might expect them to be asnumerous as us. Partners in Flight estimates, on thebasis of Breeding Bird Surveys, that there are about15 million Chimney Swifts in North America (all con-tained in an area east of the Rockies). That is indeed a

lot of birds. Yet Partners in Flight also classies themas a Common Species in Steep Decline; this des-ignation indicates birds that are still numerous, butwhose populations have declined by 50% or moreduring the past 40 years, as measured by Breed-ing Bird Survey data. To put that in perspective: ifas many humans had gone missing, enough of themwould have disappeared in the last 40 years to e mptyNew York City and all of New Jersey.

At rst glance, those birds appear not to have gone


13/21


allowed us to build all of them in one day, for lessthan $150 each, and move them in a pickup truckto four locations in Storrs and Willimantic. Then wewatched, and waited for the Chimney Swift breedingseason to begin.

The birds inspected the towers but didnt nest inany of them. Since swifts are famously attached to thesites they already occupy, maybe they didnt nd thetowers until it was too late in the season to start nestsin them. A second season, in both the same and ad-

chimneys, and lowadoption rates atChimney Swift tow-ers that were builtto provide habitatfor the birds. Takenall together, theseresults suggest thatwhatever is caus-ing the decline inthe Chimney Swiftpopulation, it isnt auniform shortage ofchimneys to nest in.

EnoughChimneys ButStill Declining

This is goodnews, right? Thereare enough chim-neys! Well, yesex-cept that the NorthAmerican popula-tion of ChimneySwifts is still declin-ing, and whatever the problem is, it is unlikely to bexed by something we can build and put out in theyard. That is unwelcome news, because we wouldprefer to have a problem we can do something about,and because we still dont know what the problem is.

ThereisagreatdealmoretobelearnedaboutChimneySwifts.

ditional locations, had the sameresult: no takers.

One explanation for this re-sult is that for some reason thetowers we built are unattract-ive to swifts. Maybe they wereinsufciently chimney-like.Maybe they were in the wrongplaces: does it matter if theyare near grassland, or trees, orwater? In an attempt to ndout what the right places are,UConn researchers surveyed thestate, counting Chimney Swiftsacross a wide variety of habi-tats: urban, rural, near water, farfrom water, forested, unforested.DEEP biologists, along with anarmy of volunteers, also counted

chimneys, recording how manywere closed and how many wereopen, and gathered data on thecharacteristics of chimneys thatswifts were nesting in, in orderto compare it to data on chim-neys they didnt occupy. We alsoconducted an email survey ofNational Audubon sanctuariesand similar organizations in sixstates and in Canada, collectinginformation on how many hadbuilt swift towers, what theirtowers were like, what the habi-tat around them was like, andhow many of them had beennested in.

What did we nd out? Wefound out that many of the as-sumptions we started with wereprobably wrong. To date, wehave been unable to demonstratestrong relationships between the

presence of Chimney Swifts andany particular habitat around the chimneys. Moresurprisingly, we also found no evidence that therewere too few chimneys; in Connecticut, at least, thereare many uncapped, unlined, empty chimneys thatare indistinguishable from those that swifts are nest-ing in. Similarly, of the 41 swift towers built by re-sponders to our email study, only 17slightly lessthan halfhave ever been known to be occupied.Finally, our colleagues at agencies and universi-ties in Canada have also documented many empty

ing now, and explains why, if you have swifts in chimney, a DEEP biologist may call you up and athey can collect droppings from your house!

DDT has long been banned in the U.S., but its unot banned in South America, where Chimney Swinter. We do not know exactly where they spthe winter and thus have no way of knowing ifhabitat there is being destroyed. We dont knowmany birds survive the trip south and back againery year; even data about how many new ChimSwifts edge every year right here in Connectichard to come by, because chicks are hidden in dinaccessible chimneys and look virtually idento adults once they begin ying. UConn and Dresearchers are continually bafed in their efforsimply quantify annual survival and productivi

Connecticut because of the dynamic and unpreable behaviors of large numbers of birds in rooschimneys.

In short, there is a great deal more to learn abChimney Swifts. Their aerial lifestyle and inaccesnest sites present a challenge to standard meanstudying birds, but this is a species worth watchThe next time you hear twittering . . . look up.

* * * * * *

Chimney Swifts are well adapted to nesting in open, vrtical chimneys.

The other causes of the population decline are bothharder to investigate and likely to be harder to solve.Joe Nocera and a group of colleagues at the OntarioMinistry of Natural Resources recently published theresults of a study of a 48-year-old deposit of Chim-

ney Swift droppings in a roost chimney. The research-ers treated the guano pile as an archeologist would,taking samples at various depths down through thepile, with deeper samples representing what the birdswere eating farther back in time. Analysis of the layersshowed that in the early 1950s, the birds underwent asteep increase in the amount of DDT in their diets; atthe same time the number of Coleopterans (beetles)in their diets decreased and the number of Hemip-tera (true bugs) increased. This shift in diet points outthe importance of nding out what the birds are eat-

SwapoutphotowithchimneyphotofromMiley/Rubega


14/21


A Colonial Cavity Nester

Ecologically, a most signicanttrait of the Purple Martin is that it isa cavity nester with a tendency forcolonial nesting. It does not create itsown cavities, however, and in prehis-toric times it would have nested pri-marily in woodpecker holes in deadtrees around beaver ponds, lakes,and other open areas, and sometimesin cliff cavities. Thus it would havehad a patchy and limited distributionin the primal, heavily forested land-scape of pre-colonial Connecticut.

Today the Purple Martin still fre-quents open landscapes such as farm-lands, suburbs, parks, and shorelinesof water bodies, but it no longer nests

in natural cavities in Connecticut andall other areas east of the Rocky Moun-tains. Rather, it depends entirely onpeople, called Purple Martin land-lords, to provide it nesting cavities inthe form of the familiar apartment-typebirdhouses or clusters of natural or ar-ticial gourds that one sees around thecountryside. For their efforts, success-ful landlords enjoy constant action andsong at their sites, and they have thesatisfaction of contributing to the spe-cies well-being.

Purple Martins AreThreatened In Connecticut

The Purple Martins shift from natural to articialnesting cavities apparently started before the rst Eu-ropean colonists arrived in North America. In his clas-sic 1810 work on American ornithology, AlexanderWilson reported that Native Americans of the South-east provided hollowed gourds as nesting sites. In thesame account, he quoted a correspondent from Penn-

sylvania who wrote about establishing Purple Martinhousing at his Harrisburg area farm in 18 00. The great

The Purple Martin,A Classic Aerialist

John Tautin

Executive Director, Purple Martin Conservation Association

The familiar andpopular PurpleMartin (Progne

subis) is North Amer-icas largest memberof the swallow fam-ily. In the spring andsummer it breeds

across the continent,but it is most com-mon in the statesand provinces eastof the Rocky Moun-tains and south ofthe coniferous forestregions of Canada.Highest densities oc-cur in the southeast-ern U.S. In Connecti-cut, Purple Martinscan be found in mostcounties, but theyare most often foundalong the coast andinlets of Long IslandSound, reflecting their affinity for open spacesand water.

Purple Martins typically nest once during the sea-son, laying four to seven eggs. The young hatch inabout 16 days. They remain in the nest being fed bytheir parents for 26-32 days. After edging, thousandsof them spend a few weeks gathering each evening

at communal roosts. They sleep at night in the roosts,leaving at dawn to go about the surrounding country-side to feed and loaf during the day. The evening gath-ering at a roost is leisurely, but the dawn departureis sudden and often can be detected by local Dopplerradar used to track weather phenomena.

Purple Martins are obligate aerial insectivores,meaning they feed only on ying insects. Studies oftheir food habits have shown that, contrary to popularopinion, they do not consume prodigious amounts of

mosquitoes. Rather, they feed higher off the groundwhere they take larger insects like ies, bees, beetles,butteries, and surprising numbers of dragonies.

Prior to the cyclical decline of insects in the fall,Purple Martins migrate south to warmer climeswhere insects remain available. Recent studies us-ing innovative tracking devices called geo-locators

have shown that most of them leave North Americaaround Labor Day, migrate slowly through Mexicoand Central America, and arrive at their Brazilianwintering grounds by early October. Brazils Ama-zon rain forest appears to be a signicant winter-ing area. In late winter, they begin migrating backto North America, returning as early as January toFlorida. They arrive back in Connecticut and the restof New England in early April, having made a re-markable round trip of 10,000 miles.

Purple Martins favor open spaces near water.

PAULJ.

FUSCO

Regardlessofthereasonsfordeclines,recruitingmorepeopletoprovidehigh-quality,well-managedhousingiskeytorestoringPurpleMartinpopulations.

American ornithologist and artist John James Aubon also wrote about them nesting in association humans, noting that Almost every country tahas a Martin box on the upper part of its signboand I have observed that the handsomer the boxbetter does the inn generally prove to be. Latethe 19th century, the introduction of the EuroStarling and House Sparrow, each an aggressive c

petitor for natural nesting cavities, accelerated PuMartins shift to human-supplied housing.The Purple Martins dependency on this kin

housing is now part of its ecology, and is fundameto both its decline and restoration. Continent-wits population has been stable for the last 50 yearcording to results from the scientically sound Bring Bird Survey conducted annually by the U.S. logical Survey. However, in the states and provisurrounding the Great Lakes and on into New Eland, populations have declined substantially. C


15/21


TogetafeelforthejoysofbeingaPurpleMartinlandlord,visitthelivewebsiteofPhilDonahuesConnecticutcolonyathttp://www.gazebophil.com/

homebodies seem to havemore interest, time, andwherewithal to care forthem than suburbanitesdo. Unfortunately, familyfarms and rural lifestylesin New England are in de-cline, and each succeedinggeneration of people hasless contact with the land.These societal changeshave produced a clas-sic vicious cycle whereinfewer people are produc-ing fewer Purple Martins,resulting in still fewerpeople coming to know,appreciate, and in turncare for them. Then, as in-

dividual colonies decline,fewer birds are availableto disperse and establishnew colonies. Without aconcerted effort to main-tain them, over the next 20 years New England willlikely lose many of its remaining colonies, especiallythose that are isolated from others.

Well-Managed Housing Is Key

Regardless of the reasons for declines, recruitingmore people to provide high-quality, well-managedhousing is key to restoring Purple Martin popula-tions. Best management practices are well dened,and the birds respond positively to them. Restorationthus is largely a matter of engaging the general pub-lic and the conservation community, educating themabout this species, and encouraging people to becomelandlords.

As in most community endeavors, leadershipis vital to this restoration. Its importance has beenproved in other parts of North America, notably inBritish Columbia and Minnesota, where under good

leadership community-based working groups aremaking a difference for these birds and the peoplewho cherish them. Fortunately for Connecticut, andindeed all of New England, the Connecticut Depart-ment of Energy and Environmental Protection hasemerged as a Purple Martin champion. DEEP, alongwith Connecticut Audubon, Menunkatuck AudubonSociety, and numerous landlords around the state arelocating, mapping, and assessing colonies, experi-menting with techniques to expand them, monitor-

acute weather-related food shortages, but long-termstudies of Purple Martin productivity do not suggestthat food shortage, weather related or otherwise, isa widespread problem. Competition for nest cavi-ties from the more aggressive European Starling andHouse Sparrow, disease, predation, and the rigors ofmigrationfactors that many migratory birds facealso cause some Martin mortality. However, none ofthese factors has been shown conclusively to be thecause of population declines. Nor is loss of habitat thelikely cause. Connecticuts Purple Martins make longdistance migrations to and from their Brazilian win-tering grounds, but migratory and wintering habitatsare not known to be limiting; and, at the landscapelevel in Connecticut; their favored open habitats re-main abundant.

While the absolute reasons for the population de-clines have not been conclusively determined, loss ofhuman-supplied housing is a likely factor. AlthoughPurple Martins tolerate suburban and even urbanenvironments, they are more common in rural en-vironments where farmers, retirees, and other rural

Well-managed housing may be the key to restoring Purple Martin populatoins.

necticut ofcially lists the Purple Martin as a Threat-ened species, meaning that, without intervention, itis likely to become an endangered species within theforeseeable future throughout all or a signicant por-tion of its range within the state.

Many reasons have been postulated for thesepopulation declines. Adverse weather is often men-tioned. Indeed, as very early spring migrants andobligate aerial insectivores, Purple Martins are vul-nerable to periods of cold, rainy weather that limitinsect activity. Local die-offs have occurred owing to

FormoreinformationonPurpleMartinsingeneralandhowyoucanhelpthembybecomingamemberofanationalorganization,visitthePurpleMartinConservationAssociationswebsiteatwww.purplemartin.org.

Milan Bull, Marlo Thomas, and Phil Donahue banding young Martins at Phils colony in We

ing production, conducting banding-based reseproducing educational materials, and publicizinrestoration effort.

You can help this effort in Connecticut by reing an existing colony or establishing a new on

PAULJ.

FUSCO

your property is not suitable, consider becomingsteward of an existing or new colony at a publication. Across North America, wannabe landare working with schools, nature centers, parks,

businesses to establish colonies at locations wherpublic can enjoy these unique birds and hopefin turn, want to care for them. Your help is neeMore than any other species, Purple Martins depon people. Working together, all of us can assurethey remain an abundant and appreciated paConnecticuts wildlife heritage.

* * * * * *


16/21


are characteristically uttered at night. During thebreeding season Common Nighthawks exhibit spec-tacular aerial displays, including steep dives termi-nated by dramatic upward swoops that produce dis-tinctive booming sounds as air passes through theirouter wing feathers. Their plumagea combinationof gray, brown, and buff often with striking splashesof white in the wings or tailrenders them practi-cally invisible when they are resting on the ground orperched longitudinally on tree branches the way theytypically do. The large eyes of most nightjars enhancetheir nocturnal visual acuity and are highly reectiveof light when illuminated at nightan easy way tospot them if they happen to be sitting on the road in

front of an automobile.

No Nest Building

Common Nighthawks begin arriving in New Eng-land from their South American wintering areas inmid-to-late May, with courtship and nesting ordinar-ily beginning sometime thereafter and the egg-layingperiod ranging from late Ma y until early July. Night-hawks do not construct a nest but simply place theirtwo heavily speckled eggs on relatively open sandy,

gravelly, or burned-over ground. With the prolition of at, gravel-topped roofs on suburban andbuildings throughout much of the 20th century, nhawks readily took to utilizing these manmade htats as an alternative to ground nesting. In the wof this urban colonization the nasal peent-ing at dbecame a familiar sound to attentive city dwelUnfortunately, however, today the sight and soof nighthawks hawking insects in front of brighlights such as those at Bostons venerable FenPark and other well-illuminated venues have becincreasingly rare.

Historically a common breeding bird througmost of New England, the Common Nighthaw

today an increasingly rare and local nesting spein many parts of the region. This decline appeabe stronger in Canada than in the United States,stronger in eastern North America than in the WIn Canada, Breeding Bird Survey (BBS) data relong-term decline of 4.2% per year from 1968 to 2In the period from 1995 to 2005 this decline ro6.6% per year. This corresponds to a 49.5% decrin the estimated population! Currently the ComNighthawk is listed as threatened by the Com

26

Bulbat in the Sky:The Legacy of a Loser?

Wayne R. Petersen

Director of Important Bird Areas, Massachusetts Audubon Society

Having grownup in a sub-urb west of

Boston, Massachu-setts, I have fondrecollections of everysummer on favor-able nights watch-ing the erratic aerial

gyrations of groupsof southward boundCommon Night-hawks (Chordeiles mi-nor) passing over myhouse at dusk. Boundfor wintering areasranging from Ven-ezuela to northernArgentina, CommonN i g h t h a w k s o rBullbats as they aresometimes knownbreed throughoutmost of North andCentral America. De-spite the regularitywith which birders are still able to witness the crepus-cular southward migration of this somewhat mysteri-ous species during the waning days of August andearly September, these late summer ights are notwhat they were in my youth. In many regions today,conditions are apparently less favorable for this spe-

cies than they were even half a century ago.What has happened to this widespread and for-merly more common species? While the answer is notentirely clear, there are several compelling hypoth-eses. But before addressing the question more fully,let us consider what we do know about nighthawks.First, they are not raptors. Although they have falcon-shaped wings and fairly long tails like certain hawkspecies, the Common Nighthawk is actually a mem-ber of the Order Caprimulgiformesa cosmopolitan

group containing 93 species worldwide (except Ant-arctica) and nine species regularly occurring in NorthAmerica. Caprimulgids tend to be rather mysterious,largely nocturnal species with short legs and weakfeet that are ill-equipped for the traditional perchingbehavior associated with passerine and other tree-

perching species. They possess tiny beaks backed byan expansive mouth opening (i.e., gape), which isuniquely designed for capturing aerial insects on thewing. Many species actually possess long, lamen-tous feathers called rictal bristles around the mouthopening, which help direct food into the open mouthas well as also possibly serving a sensory functionsimilar to the whiskers on a cat.

Many caprimulgids (e.g., Eastern Whip-poor-will)are called nightjars because their loud vocalizations

Common Nighthawks are in serious decline throughout the northeast.They are not raptors.

Nighthawks lay their eggs on open, gravel or sandy areas such as gravel rooftops.

JULIANHOUGH


17/21


Master Aerial Insectivores: BatsJenny Dickson

Supervising Wildlife Biologist, Connecticut Department of Energyand Environmental Protection

When we considerthe importantecological role

aerial insectivores play inour environment, it is im-portant to include a groupof truly master aerialists,bats. As a group, bats arethe single largest preda-tor of night-ying insects.

They provide tremendousnightly insect control ser-vices that have signicantecologicaland econom-icimpacts.

A foraging Little BrownBat (Myotis lucifugus)will consume more thanhalf its body weight ev-ery day, with nursing fe-males eating considerablymore than their own bodyweight. The slightly largerBig Brown Bat (Eptesicusfuscus) can eat eight pounds of insects a year. If youexpand these gures to include all of the individualbats in a given colony, all of the bat colonies state-wide, and all eight species of bats found in Con-necticut, the insect control benets provided by batsare phenomenal. The value of this insect control toagriculture in the United States is estimated at $22.9billion per year.

The economic value of bats does not stop there.

Bats also provide insect control services for for-est ecosystems. These benets are much harder toquantify, as little data exist on the economics of bat-related insect control in forests. But the ripple effectsare extensive, ranging from timber products to nurs-ery stock to maple syrup operations to recreationand more.

The insect consumption of bats provides equallyimportant ecological benets, such as the control ofinsect population explosions. While bats consume

a wide variety of insects, they may eat only twthree kinds of insects at a time and will take adtage of the feeding success possible when swof insects are encountered. Much like some of tavian counterparts, bats will target large inights that occur at various times of the year.example, Big Brown Bats, just like Common Nhawks, will readily take advantage of caddhatches. Whether it is an exploding populatio

Corn Borer Moths or normal June Bug activitymore insect control can be accomplished natuby bats, the less farmers and others will resocontrolling them with chemicals. Thus fewer ticides are applied to the environment or to cdestined for human consumption.

Bats Are Highly Variable

The mechanics behind this aerial insectiare anything but simple. Again, as with their a

28

tee on the Status of Endangered Wildlife in Canada(COSEWIC).

Endangered In Connecticut

Closer to home, the nighthawk is registered as en-dangered in New Hampshire and Connecticut, and islisted as a species of concern in Rhode Island. Surveysconducted by New Hampshire Audubon in the early1990s and in 2001-2002 demonstrated the disappear-ance of nighthawks from nine of 13 areas surveyedduring both periods, and the species also becamenotably less common in Concordonce a nestingstronghold for nighthawks in New Hampshire. Datafrom the Massachusetts Breeding Bird Atlas I (BBA I)conrmed the nesting of Common Nighthawks in 13atlas blocks statewide (1974-79), with all but one of theconrmations on urban rooftops. BBA II (2007-2011)revealed zero Bay State conrmations. In Connecticuta dedicated effort to locate breeding Common Night-hawks during the period 2005-2007 was unable toconrm the presence of a single nesting pair.

DatafromtheMassachusettsBreedingBirdAtlasI(BBAI)conrmedthenestingofCommonNighthawks in 13 atlas blocksstatewide(1974-79),withallbutoneoftheconrmationsonurbanrooftops.BBAII(2007-2011)revealedzeroBayStateconrmations.

factors could be adversely affecting aerial insect pop-ulations. Excessive light pollution might be disrupt-ing their nocturnal aerial activity, as might the altera-tion of wetlands that brings about changes in pH (i.e.,acidication). Or, extreme temperature modulationsresulting from uctuations in annual weather pat-terns could be affecting insect emergence times. Forspecies like the Common Nighthawk, whose long-distance migration strategy has evolved concurrentlywith a seasonally reliable abundance of insects, it maynot take much to disrupt their annual cycle or, worse,stress their population by limiting their food resourc-es. Add to these concerns the specter of exposure topernicious pesticides, some of which continue to befreely applied in many regions where nighthawksand other aerial-feeding species spend the winter,and the species could be reaching a tipping point.

Thus, while it is still occasionally possible to seehundreds of migrating nighthawks on favorable eve-

nings in late summer, especially along the Connecti-cut River Valley and at other elevated observationsites with expansive north-facing views, unquestion-ably the numbers tallied during fall migration are notwhat they once were. For example, at a long-standingand systematically monitored site near Northamp-ton, Massachusetts, cumulative Common Nighthawkfall migration totals for the period 1978-96 averagedslightly over 3900 per year. In the pe riod 1997-2005 theyearly average dropped to a little over 1800. While theprecise reasons for the decline of the Common Night-hawk are still unclear, the question remains whetherthe familiar Bullbat might be gradually losing thebattle for long-term survival.

* * * * * *

Moths make up more than half of the diet of a Red Bat which may travel several miles nighto reach favored feeding areas. During migration, Red Bats may be seen ying during dayhours.

Itseemslikely,however,thattheprecipitous decline in breedingnighthawks in eastern NorthAmericahasbeencausedbysomethingmorethanthanashortageofurbannestsites.

As gravel roofs gave way to the more efcient rub-ber and vinyl, in many areas nighthawks abandonedrooftop nesting. It seems likely, however, that the pre-cipitous decline in breeding nighthawks in easternNorth America has been caused by something morethan than a shortage of urban nest sites. The mostdisturbing hypothesis is that the quantity of yinginsectsthe aerial plankton upon which night-hawks depend for foodmay be diminishing. The

documented spectrum of insects involved in sucharthropod declines includes everything from beesand wasps to butteries and moths. Because manybat species are analogous to Common Nighthawksin their aerial foraging strategy, concern is also beingraised over their future status as well. Could it be thatthe steady warming of our climate is tipping the ar-thropod scale in ways that are incompatible with aer-ial predators that depend upon them for sustenance?

Entomologists have suggested that a number of


18/21


ies, gnats, mosqui-toes, ying ants, andsmaller beetles. Thetree-roosting Red Bat(Lasiurus borealis) isprimarily a moth eat-er (65%) but also en-joys beetles and yingants. In general, larg-er bats feed on largerinsects.

Aerial insectivoryis energetically de-manding. Bat feedingactivity is geared to-ward making forag-ing attempts as bio-energetically efcientas possible. Bats most

actively feed betweensunset and midnight.They forage longer ondry, warm eveningsthan on cold, wet ones.On bright moonlitnights when they are more readilyvisible to predators, bats stick to areaswith more tree cover and avoid wideopen areas. Not surprisingly, theseconditions are also when night-ying-insect activity is typically greatest. Un-like most of Connecticuts other bats,the Hoary Bat may come out to forageagain closer to dawn, switching froma diet of moths and beetles in the eve-ning to dragonies near dawn. Onrare occasions bats may forage duringthe day, switching to daytime-activeinsects such as butteries and bees,but this behavior is not typical.

Serious Conservation Concerns

There are some serious conservation concerns fac-ing these master aerialists and thus the ecosystemsthey help maintain. Increased urbanization resultsin habitat loss for both roosting and foraging areas.Perhaps more importantly, it often results in reducedrichness of plant and insect species, which in turnlimits the diversity and nutritional value of the spe-cies available for bats to feed on.

Wind powerone of the fastest growing formsof sustainable energyhas signicant impacts on

bat populations. North Amerihome to 45 bat species, 11 of whave been documented in mortsearches at wind energy facilThe vast majority of these batmigratory tree-roosting bats:Eastern Red Bat, the Hoary Batthe Silver-haired Bat. All threthese bats are already listed as Cnecticut species of special conowing to long-term populationclines and habitat loss. In addifour more of Connecticuts eighspecies are known to be negat

impacted by wind turbines. These include the LBrown Bat, the Northern Long-eared Bat (Myotistentrionalis), the Tri-colored Bat, and the Big Br

Bat. The state and federally endangered Indiana(Myotis sodalis) is believed to be at risk from windbines, but mortality in this species has not been dmented to date.

Both local resident bats and migrating bats hbeen killed by turbines. Bats spend a lot of their foraging and ying at the heights where turblades operate, often 29 meters to 111 meters abground level. Bat mortality is often highest wwind speeds are low, which is also when aeria

30

counterparts, the size and shape of each bat speciesplaying important roles in how and where it catch-es insects. Wing aspect ratios (wing area to wingbreadth) and wing loading (wing area to body mass)are key to what habitats and what part of the air col-umn bats forage in and to what kinds of insects theyeat. Bats that glean insects or forage very close tovegetation have low aspect and wing loading ratios;they are maneuverable but do not y very fast. Batsthat feed high above the vegetation have high aspectand wing loading ratios and are swift iers. Mostof Connecticuts bats fall somewhere between thesetwo extremes. All our bats practice aerial hawking,catching insects in ight either with their mouthsor by using their wing or tail membranes to catchthe insects and guide them to their mouths. The tiny

Tri-colored Bat (formerly known as the Eastern Pip-istrelle; Perimyotis subfavus), with a moderate wingaspect ratio and low wing loading, is very maneuver-able and able to exploit foraging areas cluttered withvegetation, making it a much more opportunisticfeeder. In contrast, the Hoary Bat (Lasiurus cinereus;high aspect ratio and high wing loading) often iesswiftly at or above the treetops in its pursuit of prey.

For most of our bat species, a lot of foraging isdone above rather than below the forest canopy. Pre-

ferred foraging habitats are often riparian forest ar-eas, forest edges and gaps, or in the case of the Hoaryand Silver-haired bats (Lasionycteris noctivagans), inclear cuts. Bats are remarkably loyal to their favoriteforaging sites, often returning to the same sites nightafter night and year after year. They may travel longdistances to reach these favored spots. In a habitat usestudy of Hoary Bats in Connecticut, it was commonfor individual bats to travel seven to ten miles everynight to reach a favored foraging area.

While b

audobon state of the birds 2013

Documents