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School of Natural

Resources and

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October-December 2004Vol. 21 No. 4pages 117-152

THE UNIVERSITY

OF MICHIGAN

EndangeredSpecies

UPDATEScience, Policy & Emerging Issues

Vol. 21 No. 4 2004Endangered Species UPDATE118

Kathryn Antkowiak is an aquarist at the Pittsburgh Zoo & PPG Aquarium. She gradu-ated with a BA in Animal Behavior and Environmental Studies. She came to the Zooeight years ago, working in areas of research and animal care before her currentposition in the Amazon Rainforest at the Aquarium.

Ixia Avilés-Vázquez studied Wildlife Management at the University of Puerto RicoHumacao Campus where she worked for three years at the Aviary on the plain pigeonrestoration project under the supervision of Dr. Raúl Pérez. Among her interests arethe interaction of fauna and socio-agricultural settings. Her current research focuseson interviewing hunters for data on bird populations.

Katia Avilés-Vázquez finished a Masters in Resource Ecology and Management atSNRE; she is currently teaching Spanish and a course in “Agriculture and SocialMovements” at the University of Michigan Residential College.

Douglas P. DeMaster is currently the science and research director of the AlaskaFisheries Science Center, NOAA Fisheries. He is also the current chair of the Scien-tific Committee of the International Whaling Commission. His primary research inter-ests include: (1) the incorporation of uncertainty in management decisions, (2) estab-lishing practical methods for implementing an ecosystem approach to management,and (3) population dynamics and management of large whales.

Thomas Hayes is an aquarist at the Pittsburgh Zoo & PPG Aquarium. He did a briefstint in animal research at a major lab in Virginia, before joining the Pittsburgh Zoo’sanimal department. He is an advocate for underappreciated and misunderstood non-game species of special concern.

Ariana Rickard is a M.S. candidate in the Resource Ecology and Management pro-gram at the School of Natural Resources at the University of Michigan in Ann Arborand is currently studying wetlands restoration and amphibian reintroduction pro-grams.

Scott R. Schlossberg is a Ph.D. student in the Program in Ecology and EvolutionaryBiology at the University of Illinois, Urbana-Champaign, where he studies the conser-vation and ecology of birds. His research interests are on the effects of drought onbirds of the Southwest, the application of animal behavior in the conservation of birds,and modeling landscape-scale patterns in ecology at the individual level.

Kim E. W. Shelden is a marine biologist with the National Marine Mammal Labora-tory, Alaska Fisheries Science Center, NOAA Fisheries. urrent projects include de-fining North Pacific right whale habitat; gray whale births north of Mexico; unusualmortality in Cook Inlet, Alaska, belugas; and stock structure of Western Arctic bow-head whales.

Edythe Sonntag is a Senior Keeper at the National Amphibian Conservation Centerand a M.S. candidate at the University of Michigan in Dearborn, where she is takingcoursework in wetlands biology, restoration ecology, and environmental chemistry.

Andrew Strassman is a Master's student at the University of Michigan's School ofNatural Resources & Environment. He participated in Wisconsin DNR organizedwolf-tracking projects while at the University of Wisconsin at Steven's Point.

Michael P. Ward is an avian ecologist at the Illinois Natural History Survey inChampaign, Illinois, where he studies avian population dynamics and habitat selec-tion. His current projects include the use of conspecific attraction in the recovery ofterns in Illinois, the effect of suburban development on wetland bird populations, thepopulation dynamics of yellow-headed blackbirds, and the effect of the West NileVirus on urban bird populations.

Kevin Zippel is a herpetologist who has specialized in amphibians for 14 years,including 6 years at the Wildlife Conservation Society and the National AmphibianConservation Center.

ContributorsEndangeredSpecies

UPDATE

Science, Policy & Emerging Issues

A forum for information exchange on endangered speciesissuesOctober-December 2004 Vol. 21 No. 4

Andrea Kraljevic…………............................................EditorHsun-Yi Hsieh......………............……........Editorial AssistantJennifer Stover............................................Editorial AssistantAndrew Strassman.......………...................Editorial AssistantMichele Tobias.......………...................…...Editorial AssistantVanessa Tobias.......………...................…...Editorial AssistantChristine L. Biela.............................Subscription CoordinatorBobbi Low......................................................Faculty AdvisorEmily Silverman.............................................Faculty AdvisorJohannes Foufopoulos..................................Faculty Advisor

Advisory BoardRichard Block

Santa BarbaraZoological Gardens

Susan Haig, PhDForest and Rangeland EcosystemScience Center, USGSOregon State University

Patrick O’Brien, PhDChevronTexaco Energy Research Company

Jack Ward Thomas, PhDUniveristy of Montana

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Cover: Barn owl in hacking pen. Photo courtesy of PaulSalvaggio.

The views expressed in the Endangered Species UPDATEmay not necessarily reflect those of the U.S. Fish andWildlife Service or The University of Michigan.

The Endangered Species UPDATE was made possible inpart by Chevron Corporation and the U.S. Fish and WildlifeService Division of Endangered Species.

Vol. 21 No. 4 2004 Endangered Species UPDATE 119

Guidelines for DevelopingStatus-Determining Criteria

Kim E. W. Shelden &Douglas P. DeMaster

National Marine MammalLaboratoryAlaska Fisheries ScienceCenter, NOAA, NMFS7600 Sand Point Way N.E.Seattle, WA 98115-6349,[email protected]

Currently, the Endangered Species Act (ESA) employs a two-tier system,listing species either as endangered (in danger of extinction) or threatened(likely to become endangered). One approach, to reassert scientific objec-tivity in the classification process, has been to develop status-determiningcriteria for each ESA category. When developing criteria, however, it is im-portant that they be not only credible but also legally defensible and fair. Inaddition, status-determining criteria should provide clear, predictable, re-peatable results. The absence of objective guidelines in the listing and re-classification process has left the entire ESA classification process open tosubjective decision making that is often inefficient, inequitable, and notlegally defensible in the court system. It is recommended that status-deter-mining criteria should be developed that are consistent with existing regu-lations, objective, equitable (i.e., based on risk of extinction), efficient (i.e.,relatively easy to implement with available data), and designed to incorpo-rate uncertainty appropriately.

Actualmente, la ley de especies en peligro de extinción (ESA en Ingles) usauna sistema de dos categorías, listando especies en peligro (de extinción) oamenazadas (con probabilidades de llegar a estar en peligro de extinción).Un método, para reestablecer la objetividad científica en el proceso declasificación, es el desarrollo de criterios que determinan el estado para cadacategoría de la ESA. Los criterios que se desarrollen deben ser no sonsolamente creíbles, pero también defendibles legalmente y justos. También,deben facilitar resultados claros, predecibles, y repetibles. La ausencia dedirectivas objetivas en el proceso del listado y reclasificación ha dejado elproceso entero abierto a decisiones subjetivas las cuales son ineficaces,injustas, y sin defensa legal en el sistema judicial. Recomendamos desarrollarcriterios que sean consistentes con regulaciones existentes, objetivos, justos(con base en el riesgo de extinción), eficaces (de relativamente fácilimplementación con los datos existentes), y diseñado para incorporar laincertidumbre de manera apropiada.

Resumen

Abstract

Endangered Species UPDATE Vol. 21 No. 4 2004120

The thrust of the U.S. Endan-gered Species Act (ESA) is the con-servation of species at risk of extinc-tion. To meet this mandate, theU.S. Fish and Wildlife Service(USFWS) and National MarineFisheries Service (hereafter referredto as the Services) must determinelevels of vulnerability based on sci-entific data. Currently the ESAemploys a two-tier system, listingspecies either as endangered (indanger of extinction) or threatened(likely to become endangered).The lack of objective guidelines todirect listing decisions has led to in-consistencies and inequities in thelisting process. Agencies oftenmake decisions based on limitedresources and under the influenceof “other social, environmental, oreconomic objectives” (Taylor et al.1996). Mangel et al. (1996) recom-mend establishing procedures toguide decision making to reducethese influences. One approach toreassert scientific objectives hasbeen to develop some form of sta-tus-determining criteria for eachESA category (e.g., Taylor et al.1996, Gerber and DeMaster 1999,Shelden et al. 2001).

When developing criteria, how-ever, it is important that they be notonly credible, but also legally defen-sible and fair. Listing and reclassi-

fication decisions must be rational-ized to the best extent possible.They should reflect the substantivepolicy goals of equity and efficiency(Weimer and Vining 1992) andmust appear to be predictable, con-sistent, and sound. It may help toconsider the following guidelines or"criteria for criteria" when selectingthresholds for endangered andthreatened status (Table 1). To beconsistent with the ESA, criteriashould work within the frameworkof the five factors and the statusdefinitions (Table 1, Point 1). List-ing and reclassification actions onthe List of Endangered and Threat-ened Wildlife (50 CFR 17.11) arebased on five factors (Table 2), ofwhich only one need apply for aspecies to be listed as either threat-ened or endangered. These five fac-tors consider the circumstancesunder which species are more vul-nerable to extinction. The factor(s)that contributed to the listing of aparticular species should be ad-dressed within the status-determin-ing criteria developed for that spe-cies. The status definitions of en-dangered and threatened shouldalso serve as a guide, albeit a broadand vague one, for establishingthresholds or benchmarks for thecategories of endangered, threat-ened, and recovered.

1. Consistent: status-determining criteria should be consistent with the conventions that currently existunder the ESA such as the five factors (see Table 2) and the status definitions.

2. Objective: criteria should be objective in the sense that they minimize interpretation and judgement.

3. Equitable: classification decisions should be equitable, guiding research and funding toward thosespecies in greatest need, not those that are more charismatic.

4. Efficient: decisions should be made efficiently, status-determining criteria should help to expedite thelisting and reclassification process by providing thresholds for each status level, and help to focusfunding and research in areas that are data deficient.

5. Address Uncertainty: status-determining criteria should include a “safety factor” for uncertainty inthe form of conservative criteria, by using models to incorporate uncertainty or by including policyalternatives that allow flexibility in the decision process.

Table 1. "Criteria for criteria"


Status-determining criteriashould provide clear, predictable,repeatable results. To be objective,criteria cannot be open to multipleinterpretations or judgements; theyneed to minimize the subjective na-ture of current listing decisions(Table 1, Point 2). Classification cri-teria should provide a clear decisionpath for managers based on whatis known, as well as not known,about the species. Developingthresholds for endangered andthreatened status links the prohibi-tive and protective measures of theESA to a goal: recovery of the spe-cies. Emphasizing the concept ofrecovery and removing the ad hocapproach to classifying speciesshould help regulators and those inthe regulated community to focuson “problem-solving” rather thanthe ESA’s prohibitions (Cheever1996).

The absence of classification cri-teria within the ESA and within theregulations promulgated by theServices makes comparisons oflevel of endangerment across taxadifficult (Easter-Pilcher 1996). Thishas led to inequities in project fund-ing where “charismatic megafauna” (high-profile vertebrates)have benefited more than otherspecies (Mann and Plummer 1992)(Table 1, Point 3). From 1981 to1986, 5% of listed U.S. species re-ceived approximately 45% of thefunding available for recovery plandevelopment and implementation(S. Rep. No. 204, 100th Cong., 1stSess. 9 (1987)). The General Ac-counting Office (GAO) noted thatthe USFWS disproportionately al-lotted resources toward “either highprofile, low-priority species, or onlow priority tasks for high-priorityspecies” (GAO 1988). This fiscaldiscrepancy continued in 1990 de-spite criticisms by the GAO and

Congress. Of $102 million appro-priated for 591 taxa, $55 millionwent to 12 species, while $28 mil-lion was shared among 570 “low-charisma” species (Winckler 1993).Species-specific status-determiningcriteria should clearly define thelevel of endangerment, enablingmanagers and decision makers todirect resources and funding to-ward those species in greatest needof protection. Criteria should alsoaid wildlife managers by revealingwhere gaps in data exist (Table 1,Point 4), allowing managers and de-cision makers to focus their researchand monitoring efforts. The resultwould be the more equitable andefficient use of an already limitedUSFWS budget (Vig and Kraft1997).

According to Holt and Talbot(1978), “management decisionsshould include a safety factor to al-low for the facts that knowledge islimited and institutions are imper-fect.” These safety factors wouldconsider the levels of risk associatedwith decisions that are based on in-complete data (e.g., Ralls et al. 1992,Maguire 1994, Taylor et al. 1996).It is of critical importance to spellout the consequences of scientificignorance to policy makers, par-ticularly when assessing potentialthreats to species survival (Taylor1993, Dovers et al. 1996, Mayer andSimmonds 1996). Otherwise, de-cision makers may use uncertainty

1. The present or threatened destruction, modification, or curtail-ment of habitat and range.

2. Overutilization for commercial, recreational, scientific, or educa-tional purposes.

3. Disease or predation.4. Inadequacy of existing regulatory mechanisms.5. Other natural or manmade factors affecting its continued exist-

ence.

Table 2. Five factors used inESA listing and reclassificationactions to consider in formingstatus-determining criteria.


as an excuse to avoid action. Crite-ria may be developed by adoptingconservative thresholds, usingmodels that incorporate uncer-tainty, or including a range of alter-native policy responses to encom-pass the range of evaluation out-comes (Table 1, Point 5).

The scientific process is fraughtwith uncertainty; it is the objectiveof science to incrementally reducethe level of uncertainty throughhypothesis testing. Causes of un-certainty range from investigatorerror and poor data collection toenvironmental stochasticity, indirecteffects, non-independent effects,and cumulative space effects (Meffeand Carroll 1994). These perceivedweaknesses in scientific analysesand data are often exploited, evendistorted, in the courtroom (e.g.,northern spotted owl litigation: seeNoon and Murphy 1994). In theseinstances, the “burden of proof” isplaced on the scientists proposinglisting rather than those planningactions that will modify habitat orharm a vulnerable species (NRC1995). Adopting scientifically de-fensible criteria might reverse thistrend in the courts by “rationaliz-ing” the listing decision.

“...a decision may be ratio-nal if it can be tested or "veri-fied" against criteria or data de-termined independently and ifit satisfies a goal thought, ona priori grounds, to be appro-priate for that science. The cri-teria and the data used are sup-posed to be "objective" in thesense that they minimize inter-pretation and judgement sothat, at least in principle, any-one who applies the same cri-teria to the same data will getthe same result... .” (Sagoff

1987:308).

The absence of objective guide-lines in the listing and reclassifica-tion process has left the entire pro-cess open to subjective decisionmaking that is often inefficient, in-equitable, and not legally defensiblein the court system. Consideringthe five points provided in Table 1,status-determining criteria shouldprovide decision makers with thetools they need to make defensibledecisions that support best man-agement practices in the face of sci-entific uncertainty.

Literature cited

Cheever, F. 1996. The road to recovery: anew way of thinking about the Endan-gered Species Act. Ecology Law Quar-terly 23(1):1-78.

Dovers, S. R., T. W. Norton, and J. W.Handmer. 1996. Uncertainty,sustainability, ecology, and policy.Biodiversity and Conservation 5:1143-1167.

Easter-Pilcher, A. 1996. Implementing theEndangered Species Act - assessing thelisting of species as endangered orthreatened. BioScience 46(5):355-363.

GAO [General Accounting Office]. 1988.Endangered species - management im-provements could enhance recoveryprogram. Report No. RCED-89-5. Gen-eral Accounting Office, Washington,D.C.

Gerber, L.R., and D.P. DeMaster. 1999. Aquantitative approach to EndangeredSpecies Act classification of long-livedvertebrates: application to the North Pa-cific humpback whale. Conservation Bi-ology 13:1-12.

Holt, S. J., and L. M. Talbot. 1978. Newprinciples for the conservation of wildliving resources. Wildlife Monographs59:6-33.

Maguire, L.A. 1994. Decision analysis inconservation biology. Pages 327-329 inG. K. Meffe and C. R. Carroll, editors.Principles of conservation biology.Sinauer Associates Inc., Sunderland,Massachusetts, USA.

Mangel, M., L. M. Talbot, G. K. Meffe, M. T.Agardy, D. L. Alverson, J. Barlow, D. B.Botkin, G. Budowski, T. Clark, J. Cooke,R. H. Crozier, P. K. Dayton, D. L. Elder, C.W. Fowler, S. Funtowicz, J. Giske, R. J.


Hofman, S. J. Holt, S. R. Kellert, L. A.Kimball, D. Ludwig, K. Magnusson, B. S.Malayang III, C. Mann, E. A. Norse, S. P.Northridge, W. F. Perrin, C. Perrings, R.M. Peterman, G. B. Rabb, H. A. Regier, J.E. Reynolds III, K. Sherman, M. P.Sissenwine, T. D. Smith, A. Starfield, R.J. Taylor, M. F. Tillman, C. Toft, J. R. Twiss,Jr., J. Wilen, and T.P. Young. 1996. Prin-ciples for the conservation of wild livingresources. Ecological Applications6(2):338-362.

Mann, C. C. and M. L. Plummer. 1992. Thebutterfly problem. The Atlantic Monthly269(1):47-70.

Mayer, S., and M. Simmonds. 1996. Sci-ence and precaution in cetacean con-servation. Pages 390-406 in M. P.Simmonds and J. D. Hutchinson, editors.The conservation of whales and dol-phins. John Wiley & Sons, New York,New York, USA.

Meffe, G. K. and C.R. Carroll. 1994. Prin-ciples of conservation biology. SinauerAssociates Inc., Sunderland, Massachu-setts, USA.

NRC [National Research Council]. 1995.Science and the Endangered SpeciesAct. National Academy Press, Wash-ington, D.C., USA.

Noon, B. R., and D. D. Murphy. 1994. Man-agement of the spotted owl: the inter-action of science, policy, politics, and liti-gation. Pages 380-388 in G.K. Meffe andC.R. Carroll, editors. Principles of con-servation biology. Sinauer AssociatesInc., Sunderland, Massachusetts, USA.

Ralls, K., R. A. Garrott, D. B. Siniff, and A.M. Starfield. 1992. Research on threat-ened populations. Pages 197-216 in D.R. McCullough and R. H. Barrett, editors.Wildlife 2001: populations. Elsevier Pub-lishers, London, UK.

Sagoff, M. 1987. Where Ickes went rightor reason and rationality in environmen-tal law. Ecology Law Quarterly 14:265-323.

Shelden, K. E. W., D. P. DeMaster, D. J.Rugh, and A. M. Olson. 2001. Develop-ing classification criteria under the U.S.Endangered Species Act: bowheadwhales as a case study. ConservationBiology 15:1300-1307.

Taylor, B. L. 1993. “Best” abundance esti-mates and best management: why theyare not the same. U.S. Department ofCommerce, NOAA Technical Memoran-dum NMFS-SWFSC-188. 20 p

Taylor, B. L., P. R. Wade, R. A. Stehn, and J.F. Cochrane. 1996. A Bayesian approachto classification criteria for spectacled

eiders. Ecological Applications6(4):1077-1089.

USFWS [U.S. Fish and Wildlife Service].1994. [Draft] spectacled eider recoveryplan. Anchorage, AK, Appendix II, p. 3.Available? Check to see if quote is inUSFWS [U.S. Fish and Wildlife Service].1996a. Spectacled eider recovery plan.Anchorage, Alaska, USA

Vig, N. J., and M. E. Kraft. 1997. Appendix3: budgets of selected environmentaland natural resource agencies (in bil-lions of dollars). Page 398 in N. J. Vigand M. E. Kraft, editors. Environmentalpolicy in the 1990s: reform or reaction.CQ Press, Washington, D.C., USA.

Weimer, D. L., and A. R. Vining. 1992. Policyanalysis concepts and practice. PrenticeHall, Englewood Cliffs, New Jersey, USA.

Winckler, S. 1993. Stopgap measures.Atlantic 269:74-79.


Rodent Pest Control Through theReintroduction of an ExtirpatedRaptor Species

Kathryn Antkowiak& Thomas Hayes

Department of Aquatic LifePittsburgh Zoo & PPGAquariumPittsburgh, PA 15206

[email protected]

Zoos, by nature, are breeding grounds for high numbers of rodents. The useof poisons and traps has been the main tool for rodent control. By acquiringand reintroducing avian predators, specifically barn owls, into a zoo setting,the rodent population could be controlled naturally. Barn owls (Tyto alba)once flourished in Pennsylvania and surrounding areas, particularly in oldwooden barns, but the development of new prefabricated barns has left theowls with fewer places to nest. This study focuses on installing several man-made nest boxes for three avian predators on the grounds of the PittsburghZoo & PPG Aquarium and surrounding areas. In time, it is hoped that theowls will begin to breed and higher densities will be achieved, as well as asuppressed rodent population.

Los zoos son tierras de reproducción para muchos roedores. El uso del venenoy trampas son los métodos principales para controlarlos. Con la adquisicióny re-introducción de predadores naturales, específicamente el búho degranero, en un zoo, la población de roedores puede ser controladanaturalmente. Los búhos (Tyto alba) fueron muy abundante en Pennsylva-nia y sus alrededores, particularmente en los graneros viejos de madera,pero el desarrollo de graneros pre-fabricados ha dejado a los búhos con menoslugares para criar. Este estudio se enfoca en la instalación de tres criaderosartificiales para tres aves predadoras en el Pittsburgh Zoo & PPG Aquario ysus alrededores. Con el tiempo, esperamos que los búhos se empiecen aprocrear y lleguen a una densidad mas alta, además de suprimir la poblaciónde roedores.

Abstract

Resumen


Introduction

The Pittsburgh Zoo & PPGAquarium is a 77-acre natural habi-tat that lies within the confines ofthe city and surrounding develop-ment. It is adjacent to a major citypark, Highland Park, which servesas a refuge for all types of wildlife.Due to large amounts of availablefood, year-round heated buildings,and the varied ground cover, thereis an unusually high rodent popu-lation at the Pittsburgh Zoo. Ro-dent control is an ongoing concernbecause of the loss of grain andstructure damage these rodents cancause. Mice and rats are also po-tential vectors of various diseases.

Mark Browning, an animaltrainer and researcher at the Pitts-burgh Zoo & PPG Aquarium, hasalways had an interest in environ-mental concerns as well as a pas-sion for birds. In 1996, he proposeda plan to place nest boxes through-out the zoo for three avian preda-tors: the barn owl (Tyto alba),screech owl (Otus asio), and thesparrow hawk (Falco sparverius).The goal was to achieve an increasein the population of those predatorsby providing the nest boxes, and tosome degree, that increase couldeffect rodent control. Many stud-ies have shown positive correlationbetween the numbers of prey andtheir predators. Serventy andWhittel (1950) determined that asignificant increase in the averageclutch size of three raptor speciesoccurred when the recently intro-duced rabbit moved into theirrange in Australia; and Welty (1975)comments: “Hawks and owls gen-erally have larger clutches in yearswhen mice are abundant.” MarkBrowning was inspired to conducthis study by projects that used barnowls as pest control in vineyardsthroughout the United States and

palm oil nut plantations in south-east Asia. Also, he saw the impor-tance of trying to reestablish barnowls in an area where they had oncebeen extirpated because of defor-estation, urbanization of rural areas,and the use of pesticides.

Methods

Mark Browning’s study willcompliment the Integrated PestMaagement (IPM) program alreadyestablished by the Horticultural De-partment at the Pittsburgh Zoo &PPG Aquarium. They are focusingon plant insect pests along withmice, roaches, and ants in the in-door amazon rainforest exhibit.

With the zoo’s high densities ofrodents (deer mice, white-footedmice, house mice, shrews, moles,and Norway rats), a relatively highdensity of rodent predators couldbe achieved. To do this, a largenumber of nest boxes were erectedand mounted to trees on zoogrounds, to provide a safe haven forand attract the certain raptor spe-cies. Frank Pizzi, Curator of Horti-culture and Grounds at the Pitts-burgh Zoo & PPG Aquarium, do-nated the material used to build 20screech owl and kestrel boxes.These are approximately 10” deep,16” high, and 10” wide. In addition,a total of five barn owl boxes werebuilt. They are 18” cubes with a 4”entrance hole. All of the nest boxeshave ventilation holes on the sidesand top and a hatch to open forviewing and cleaning. The 20screech owl boxes, along with threebarn owl boxes, were placed ran-domly around the zoo grounds.Two of the barn owl boxes wereplaced in a 30’ x 12’ x 12’ hackingpen (figure 2). A hacking pen is anopen flight cage that is traditionallyused to rear or rehabilitate a raptorfor release back into the wild. It is a

Figure 1. Barn owls in a nest box.


means of introduction, breeding,and to simulate a home for the birdto recognize and feel comfortablein. Also, within the pen, youngowls can learn to hunt. Unlikeother hacking pens whererehabilitators use dead mice, Markuses live mice and places them inthe pen for the owls to naturally findon their own. The hacking pen usedin this study was divided in half forbreeding purposes. Mark acquired13 barn owls (pairs and babies)from Flamingo Gardens in Florida,two from the Bronx Zoo, and onemale from Elmwood Park Zoo inNorristown, Pa. One breeding pairis housed on one end of the hack-ing pen, while one male occupiesthe other end awaiting a female.One pair was given to a private landowner with a breeding facility, notfar from the zoo. Another pair wasgiven to The National Aviary inPittsburgh, where the babies fromthat pair are destined to come backto the zoo to be released. In early2004, Mark did release four adultbarn owls; one has been seen hunt-ing on zoo grounds. As well as the

boxes set up at the Pittsburgh Zoo& PPG Aquarium, West Deer HighSchool became involved and set upan additional 13 barn owl nestboxes in the West Deer District, afew miles from the zoo.

Throughout the breeding sea-son, which begins in the late win-ter/early spring, the boxes arechecked regularly for use. This isdone by the naked eye, throughbinoculars, and by checking theground beneath for signs of use(pellets, droppings, etc.). Nestboxes in use will be visited andchecked at a point some time afterthe babies have hatched and priorto their fledging to determine thenumber of successful young. Eachyear, the number of breeding pairsand successfully reared young willbe compared to previous yearsnumbers. Owls have traditionallybeen counted through broadcast-ing tapes of their calls to draw themdown into a spotlight for individualidentification. This study is pro-jected to continue until it is deter-mined that maximum density ofavian predators has been estab-lished or a desired degree of rodentcontrol has been achieved.

Results

This project has resulted in suc-cessfully acquiring and establishingthree different breeding pairs ofbarn owls, the young of which willbe released in hacking areas. In2004, three eggs successfullyhatched from the breeding pair inthe hacking pen at the zoo, whichMark plans to release in the springand summer of 2005. The NationalAudubon Society has encouragedprograms like this, since similar ef-forts to put up nests in Delaware,New Jersey, and Florida have hadgreat success. In Pennsylvania, over100 barn owl boxes have been

Figure 2. Diagram of a hacking pen.


erected in adjacent counties by theMoraine Preservation Fund, whichwas independent of Mark’s project,but led to a cooperative effort.

Conclusions

Mark Browning’s efforts, so far,have developed into a two-prongproject: to utilize raptors as part ofan Integrated Pest Managementprogram and to reestablish barnowls in an area where they had oncebeen extirpated. As far as is known,such an experiment has never beenconducted on the grounds of a zoo-logical institution. Positive resultscould potentially benefit such insti-tutions by using this as a low-cost,natural pest control and the insti-tutions could provide more safehavens to these vulnerable raptorspecies. On a conservation note, thisproject could also help reduce oreliminate the need for rodent poi-sons or traps. Mark Browningwanted barn owls to “get out thereand start breeding on their own.”With the help of the distributed nestboxes, he believes the animals willessentially establish themselves aslocal residents and part of the localindigenous wildlife population.This is quite notable, since the sub-jects studied are probably the firstbreeding barn owls in AlleghenyCounty in quite some time. Markhopes to eventually get funding forsatellite telemetry, which is a newtool for wildlife research and man-agement. It determines the locationof the bird, throughout the world,by transmitters that are attachedunder its wing. This would helpwith monitoring the movement ofthe species, enabling researchers tosee the distribution, preferred habi-tats, and where they feed. The lossof nesting sites and lack of naturalhabitat has practically wiped out thebarn owl population in Pennsylva-

nia and several other states. WithMark’s efforts to reintroduce thisspecies to our area, satellite telem-etry would definitely benefit thisproject by making it easier to moni-tor barn owls in a wider range.

For more information on the owl project, con-

tact Mark Browning at 412-365-2395.

Literature Cited

Craighead, J.J. and F.C. Craighead, 1969. Hawks,Owls, and Wildlife. Dover Publications, Inc.,New York, New York.

Serventy, D.L. and H.M. Whittel, 1950. AHandbook of the Birds of Western Australia.Second Edition. Patterson Press, Perth,Australia.

Welty, C.S. 1975. The Life of Birds. W.B.Saunders Company, Philadelphia, Pennsylva-nia. p.305.

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Amphibian Conservation Strategies:Translocating an Entire Population ofBlanchard's Cricket Frog (Acriscrepitans blanchardi) in SoutheastMichigan

Ariana Rickard,1

Edi Sonntag,2 andKevin Zippel3

1School of Natural Resourcesand EnvironmentUniversity of Michigan,Ann Arbor430 E. UniversityAnn Arbor, MI [email protected]

2National AmphibianConservation CenterDetroit Zoological Institute8450 West Ten Mile Rd.Royal Oak, MI 48068-0039

325 Spring StreetUnion Springs, NY 13160

The dramatic decline of amphibian populations worldwide is an urgent conserva-tion issue. The root causes underlying many amphibian declines are unknown.One Michigan species of Special Concern, the Blanchard’s cricket frog (Acris crepitansblanchardi), is declining at an alarming rate in the northern portions of its range. InMay 2004, the National Amphibian Conservation Center (NACC) at the DetroitZoo initiated a translocation project to reintroduce Blanchard’s cricket frog to threemanmade wetlands at the northern extent of its range. Calling surveys in south-east Michigan revealed several robust populations of cricket frogs including onesite slated for development in the fall of 2004. Working with the developer and theDepartment of Environmental Quality, we successfully removed about 1,050 frogsand tadpoles from the threatened breeding ponds. The animals were released intotwo Michigan Department of Natural Resource restored lake plain prairie com-plexes with wetland features, and into a restored wetland near the NACC in fall of2004. These translocated populations will be monitored in subsequent breedingseasons to assess the success of the translocation project.

ResumenLa drástica disminución de poblaciones de ranas alrededor del mundo es unproblema de conservación urgente. Las causas fundamentales de muchas de estasdisminuciones son desconocidas. Una especie de preocupación especial en Michi-gan, el Blanchard’s cricket frog (Acris crepitans blanchardi), esta decayendo a unavelocidad alarmante en el parte norte de su cobertura. En mayo de 2004, el CentroNacional de Conservación Anfibio (NACC) en el zoo de Detroit empezó un proyectode traslocación para re-introducir la rana Blanchards en tres humedales artificialesen la parte norte de su cobertura. Estudios de las llamadas en el suroeste de Michi-gan ha revelado algunas poblaciones robustas de las ranas, incluyendo un sitioplaneado para la construcción de casas en el otoño de 2004. En colaboración con eldiseñador y el Departamento de Calidad Ambiental, hemos retirado con buenéxito 1,500 ranas y renacuajos de los estanques amenazados. Los animales fueronliberados en dos lagos restaurados del Departamento de Recursos Naturales concaracterísticas de humedales, y en un humedal restaurado cerca de NACC en elotoño de 2004. Estas poblaciones translocadas serán vigiladas en las etapas siguientesde cría para evaluar el éxito del proyecto de traslocación.

Abstract


According to a recent global sur-vey of all 5,743 known amphibianspecies, almost a third (1,856 spe-cies) are threatened with extinction(IUCN, CI, and NatureServe 2004).An additional 1,300 other speciesare probably also threatened, butscientists did not have sufficientdata to assess their status (Ibid.).Amphibian populations are declin-ing more rapidly than either birdsor mammals (Ibid.). While manyamphibian declines can be attrib-uted to habitat loss andoverexploitation, the root causes ofother species declines are un-known. The Blanchard’s cricketfrog (Acris crepitans blanchardi), aMichigan species of Special Con-cern, is declining in some areas ofthe Midwest, and scientists havenot been able to determine why thespecies is threatened in the north-ern extent of its range.

Blanchard’s cricket frog is asmall (0.6 to 1.5 in), warty-skinnedfrog with long hind limbs and is re-lated to tree frogs, but lacks toe padson its feet and does not climb. Theyusually inhabit the more openedges of permanent ponds, bogs,lakes, and slow-moving streams orrivers (Harding 2000). Blanchard’scricket frog is one of three subspe-cies of the northern cricket frog(Acris crepitans) and ranges fromsouthern Michigan, Wisconsin, andsoutheastern South Dakota souththrough Texas, west to northernMexico, and east to northern Ten-nessee. The call of this cricket frogresembles a series of metallic clicks,similar to the sound made whentwo pebbles are tapped together(Harding 2000). Blanchard’s cricketfrog was named in 1947 after dis-tinguished University of Michiganherpetologist Frank NelsonBlanchard.

Since the late 1970s and 1980s,

populations of Blanchard’s cricketfrog have declined drastically in thenorthern portions of its range(Harding 2000). These declineshave been documented in Ontario,Iowa, Wisconsin, Indiana, Illinois,Michigan, Ohio, and Minnesota.While the species has been extir-pated from some areas, such asOntario and most of southeastMichigan, the cricket frog remainscommon in the southern and west-ern parts of its range. Potentialcauses for this decline include con-tamination of wetlands and water-ways by pesticides or other pollut-ants, successional changes in habi-tat characteristics, climatic fluctua-tions, competition and predationfrom other frog species (e.g., bull-frogs and green frogs), drought,acid rain, and habitat loss and frag-mentation (Lehtinen 2004, Harding2000). Some life history character-istics of this frog, such as a short lifespan and limited dispersal, mightmake it especially vulnerable to pe-riodic extinctions at the peripheryof its range. To test the hypothesisthat cricket frogs are declining insoutheast Michigan due to the lossof migration corridors, which allowfor recolonization in new areas,Kevin Zippel, former curator of theNational Amphibian ConservationCenter (NACC), initiated a translo-cation project to try to establish aself-sustaining population of cricketfrogs in a restored wetland at theDetroit Zoo.

Ariana Rickard, a summer in-tern at NACC, conducted the ini-tial population surveys to identifyviable local populations that couldbe used as source animals for thetranslocation project. Rickard fol-lowed up on population surveysdone by Richard Lehtinen on thedistribution of Blanchard’s cricketfrog in southeastern Michigan

Figure 1. Acris crepitans blanchardi


(Lehtinen 2002). Between May 18and July 9, 2001, Lehtinen surveyed60 sites that historically hostedcricket frog populations. Only twoof these sites in southeast Michigan,Ypsilanti and Tecumseh, had cricketfrogs and full choruses of males.Lehtinen concluded, “Blanchard’scricket frogs are not only declining,but are nearly extirpated fromsoutheast Michigan.” On May 18,2004, Rickard visited the same siteLehtinen surveyed in Ypsilanti andheard cricket frogs calling fromthree different sites near Ford Lake.One property, Lakewood Farms,seemed to host the largest popula-tion of cricket frogs in the area.

After Rickard located thecricket frog populations fromnighttime calling surveys near FordLake, she identified the owners anddevelopment plans for the breed-ing ponds. The developer of Lake-wood Farms had plans to build con-dominiums and single-familyhomes on the property, and in-tended to fill in the cricket frogbreeding ponds for the entrancedriveway into the complex. Thecompany had hired a consultant,Applied Science and Technology,Inc. (ASTI), to survey the site for

cricket frogs and two threatenedplant species. After ASTI concludedthat there were no cricket frogs onthe property, the developer statedthat it didn’t “make sense” for themto give NACC permission to relo-cate the frogs.

ASTI surveyed the site threetimes in April and May 2004 andconcluded, “the site does not con-tain the preferred habitat for thesubject species . . . . None of the sub-ject species were encountered dur-ing the assessment” (ASTI Threat-ened and Endangered Species Sur-vey 2004). However the consult-ants’ survey was performed with-out proper consideration for the an-nual cycle of the cricket frogs, andthe surveys were conducted whenthe Blanchard’s cricket frogs wereunlikely to be found during visualencounter surveys. Calling surveysconducted during this frog’s breed-ing season would have provided amore reliable assessment of the sizeof the cricket frog population atLakewood Farms.

Zoo staff contacted the Depart-ment of Environmental Quality(DEQ) and a DEQ representative,James Sallee, served as a liaison be-tween NACC and the developer.Sallee convinced the developer toallow NACC to remove the frogsfrom the property before develop-ment began. Representatives of allparties involved surveyed the sitein July 2004 and confirmed a sig-nificant numbers of cricket frogs.With this information, the DEQmandated that Edi Sonntag, SeniorZookeeper at NACC, must approveplans for the required mitigationsite. Sonntag is researching thehabitat requirements of this speciesand was surveying the extant south-east Michigan populations. Thissurvey information was then ap-plied to the design of the mitigation

Lakewood Farms rescue site.


site to assure replacement of appro-priate cricket frog habitat.

Sonntag also began recruitingvolunteers for the frog rescue effort.After the Department of NaturalResources (DNR) approved emer-gency collection permits for thecricket frogs and the Zoo’s veteri-nary staff completed health assess-ments on the Lakewood Farmsfrogs to verify that there were nocontagious diseases present in thepopulation, groups of volunteersled by Sonntag began collectingfrogs 2–3 times a week in Augustthrough October 2004. About1,050 frogs and tadpoles were re-moved and released into two DNRparks and the wetland near theNACC in September 2004. Thesesites were selected after careful con-sideration of habitat qualities, suchas shoreline vegetation and waterquality, and after health assessmentsof resident amphibian populationsrevealed no problematic diseases orparasites.

Sonntag, Zippel, and Rickardvisited the three introduction sitesapproximately one month after thefrogs were released and found nu-merous cricket frogs basking ormoving through their new homes.About 10% of the released frogswere seen at all the introductionsites, an encounter rate similar towhat we have observed at Lake-wood Farms. From our populationsurveys at Lakewood Farms, weknow that the number of individu-als seen at any one time is about10% of the total population.Sonntag and Rickard plan to con-tinue to monitor the translocatedpopulations in the spring of 2005.Hopefully, the cricket frogs willthrive in their new homes, and wewill hear strong choruses at all threeof the introduction sites next May.

Literature Cited

Applied Science and Technology, Inc. Threat-ened and Endangered Species Survey: Lake-wood Farms Property. May 28, 2004.

Harding, J.H. 2000. Amphibians and Reptiles ofthe Great Lakes Region. Ann Arbor: Univer-sity of Michigan Press. 378 pp.

IUCN, Conservation International, andNatureServe. 2004. Global Amphibian Assess-ment. <www.globalamphibians.org>. Down-loaded on 17 November 2004.

Lehtinen, R.M. 2002. A historical study of thedistribution of Blanchard’s cricket frog (Acriscrepitans blanchardi) in southeastern Michi-gan. Herpetol. Rev. 33(3):194-197.

Lehtinen R. M. March 6, 2004. The status ofBlanchard’s cricket frog populations in south-ern Michigan: implications for declines in Ohio.Ohio Declining Amphibians Population TaskForce Meeting. Columbus, Ohio.


Using Conspecific Attraction toConserve Endangered Birds

Scott R. Schlossberg1

& Michael P Ward2

1Program in Ecology andEvolutionary BiologyUniversity of Illinois606 E. Healy St.Champaign, IL [email protected]

2Department of AnimalBiologyUniversity of Illinois606 E. Healy St.Champaign, IL [email protected]

Conspecific attraction, the tendency for individuals of a species to settle nearone another, may provide managers and conservationists with a new tool forthe recovery of many bird species. Conspecific attraction has been used inthe recovery of colonial birds for over 20 years, and recent research suggeststhat conspecific attraction may occur in a number of territorial birds. Cuessuggesting the presence of conspecifics can potentially be used to attract indi-viduals to previously unoccupied sites that are managed for the species’ ben-efit. In this article, we discuss the ecological issues surrounding the use ofconspecific attraction for managing birds, including which cues should beused to attract birds, when these cues should be used, which species are likelyto exhibit conspecific attraction, and other factors that should be consideredbefore attempting to attract individuals to a site.

Resumen

Abstract

La atracción de coespecies, o tendencia de individuos de una especie paraestablecerse cerca de otros, puede facilitar un método nuevo para larecuperación de diferentes especies de pájaros. El metodo ha sido usado enla recuperación de pájaros coloniales por los últimos 20 anos, y estudiosrecientes sugieren que la atracción de coespecies puede ocurrir en algunoscuantos pájaros territoriales. Posiblemente, las señales que sugieren lapresencia de coespecies pueden ser usadas para atraer individuos a sitiospreviamente desocupados y manejados para el beneficio de la especie. Eneste articulo, discutimos las cuestiones ecológicas sobre el uso de la atracciónde coespecies por el manejo de pájaros, incluyendo cuales señales deben serusados para atraer pájaros, y otros factores que se deben considerar antes deintentar atraer individuos a un sitio.


IntroductionConspecific attraction is the ten-

dency for animals to settle nearother members of their species.This behavior is most conspicuousin colonial species that settle in closeproximity to one another and es-chew living alone (Burger 1988).Colonial species presumably ben-efit from the presence of conspecif-ics through improved ability to lo-cate food or ward off predators.Territorial animals, on the otherhand, actively defend space againstconspecifics. Furthermore, as thedensity of territorial animals in-creases, reproductive success oftendecreases due to density-dependenteffects (Sinclair 1989; Newton1998). As a result, until recently,few ecologists considered the pos-sibility that conspecific attractionmay also occur in territorial animals,including the vast majority of birds(Lack 1968). In contrast to predic-tions based on theory, a series ofstudies by Stamps showed that liz-ards actually prefer to settle nearconspecifics, even when unoccu-pied habitat is available nearby(Stamps 1987; 1988; 1991). Shetermed this behavior conspecifc at-traction and suggested that animalsshow it because the presence of con-specifics in an area is a reliable cueof habitat quality. Now, many ofthe best examples of conspecific at-traction in territorial animals comefrom birds (Graber 1961; Sherry &Holmes 1985; Herremans 1993;Muller et al. 1997; Poysa et al. 1998).

If this behavior is widespread interritorial birds, it may have impor-tant implications for how birds usespace and, therefore, for their con-servation and restoration (Smith &Peacock 1990). Animals that pre-fer to settle near conspecifics maybe unlikely to settle in empty ornewly created habitat patches. Con-

servationists could potentially usethis preference for previouslysettled sites to “fool” animals intosettling at unoccupied sites by arti-ficially introducing the cues natu-rally produced by conspecifics(Reed & Dobson 1993). To testwhether or not territorial birdsare attracted to conspecifics whensettling, we conducted an experi-ment on the federally endangeredblack-capped vireo (Vireo atri-capilla)(Ward & Schlossberg 2004).During spring 2000 and 2001, weplayed vireo vocalizations at sites inCentral Texas with appropriatehabitat where either one or no pairsof vireos had been present duringthe previous year. At each sitewhere we played vireo songs, thepopulation of vireos increased dur-ing the first year of playbacks. In afew cases, results were striking, withup to 30 vireos settling at previouslyunoccupied sites. Birds attracted tothese playback sites paired, bred,and in most cases had high repro-ductive success. These results pro-vide experimental confirmationthat conspecific attraction occurs inat least one territorial songbird.Furthermore, the results suggestthat conspecific attraction can pro-vide a powerful tool for managingand conserving birds. The purposeof this article is to discuss some ofthe ecological factors that need tobe considered when using conspe-cific attraction as a managementtool for birds.

Cues to Attract BirdsTwo types of cues could poten-

tially be used to attract birds to asite: vocalizations and models.Birds produce a variety of vocaliza-tions that could be used for play-backs. Avian vocalizations includesongs (complex, learned vocaliza-tions produced only by passerines)


and calls (relatively simple, un-learned vocalizations produced byall types of birds). For songbirds,we suggest primarily broadcastingsongs for two reasons. First, songsare the most conspicuous vocaliza-tions given by most birds, and sec-ond, they indicate the presence ofan occupied territory, which couldmake an area attractive for birds.Other vocalizations such as chipnotes, flight calls, and alarm callscan be included as well to increasethe variety of vocalizations and re-duce habituation by birds. In ourresearch with black-capped vireos,we used CDs with approximately50 min of vireo songs and 5 min ofother vireo calls. For non-passe-rines, we suggest primarily usingterritorial advertisement calls, asthese are the calls most frequentlygiven by these birds.

While models may be impor-tant cues for attracting colonial birdsto new breeding sites (Podolsky &Kress 1992; Kress 1997), modelsmay not always be important forterritorial species. This should beespecially true for small, crypticbirds or for those that inhabit densevegetation because these specieswould be unlikely to rely on visualcues to determine the presence ofconspecifics. In contrast, conspicu-ous birds that use open habitatsmay be more likely to use visualcues and would be better candi-dates for the use of models. Wetested whether models and play-backs were necessary to attract theshy black-capped vireo as well asthe large, conspicuous yellow-headed blackbird (Xanthocephalusxanthocephalus) to new sites. Notsurprisingly, vireos did not respondto conspecific models at all (Ward& Schlossberg 2004). In contrast,yellow-headed blackbirds were at-tracted to sites where models and

vocalizations were used but failedto occupy sites that had either mod-els alone or vocalizations alone(Ward unpubl. data).

Timing of PlaybacksAlthough most songbirds are di-

urnal, they primarily migrate atnight (Kerlinger & Moore 1989).This raises the important questionof what time of day to broadcastvocalizations. Playing songs con-tinuously may be unwise or imprac-tical because continuous play couldstress settlers and create greater en-ergy demands than the powersource for the playback system canprovide. Early morning may be thekey time to play vocalizations toattract new settlers as recent re-search suggests that settling malesassess sites at dawn, during thedawn chorus (Amrhein et al. 2004).Since songbirds migrate at nightand settle at or before dawn, wesuggest playing vocalizations fromlate night through early morning.For instance, in our study of black-capped vireos, we played songsfrom roughly two hours beforedawn until four hours after and forone to two hours each afternoonbecause occasional playbacks dur-ing the day may reinforce the per-ception that a site is occupied. Toattract nocturnal species, we sug-gest playing their vocalizationsthroughout the night because, likediurnal birds, nocturnal species mi-grate at night.

In addition to the time of theday, the seasonal timing of play-backs may also be important. Tomaximize the number of potentialsettlers exposed to playbacks, wesuggest beginning playbacks a fewdays before the typical first arrivaldate for the target species at a studylocation. Continuing playbacksthrough the breeding season is rec-


ommended because many indi-viduals disperse or prospect withinthe breeding season. In our re-search with black-capped vireos,the number of vireos on each siteincreased gradually through thefirst 2 months of each breeding sea-son (Ward and Schlossberg unpubl.data). Furthermore, many speciesprospect for potential breeding sitesat the end of the breeding season(Reed et al. 1999), so playbacksnear the end of one breeding sea-son may help to attract birds the fol-lowing year.

Species that May Exhibit Conspe-cific Attraction

Given the small number of spe-cies studied to date, little is knownabout which species exhibit con-specific attraction. Since we com-pleted our original study on black-capped vireos, subsequent researchhas found that several species didnot settle in response to playbacksat unoccupied sites (Schlossbergand Ward unpubl. data). Thesespecies include yellow-headedblackbird, prairie warblers(Dendroica discolor), and woodthrush (Hylocichla mustelina). Incontrast, Henslow’s sparrow(Ammodramus henslowi), grass-hopper sparrow (Ammodramussavannarum), and cerulean warbler(Dendroica caerulea) did not settlein response to playbacks at unoc-cupied sites. We suggest that can-didate species likely to respond toplaybacks can be identified basedon their behavior and ecology.Characteristics of species likely torespond to conspecific attractioninclude being migratory, singingnocturnally, and having a clumpeddistribution.

Migratory vs. nonmigratory spe-cies. Migratory species are likely tobe better candidates for conspecific

attraction than nonmigratory spe-cies. Because migratory speciesmove en masse each spring, a largenumber of birds is likely to movethrough any given area over a rela-tively short period of time. Play-backs, therefore, can be targeted toa time when many birds may po-tentially hear the playbacks. Fur-thermore, because migratory birdsexhibit low natal philopatry(Weatherhead & Forbes 1994)many migrating birds will be year-lings searching for breeding sites forthe first time. These younger birdsmay be especially susceptible to ar-tificial cues (Ward & Schlossberg2004), which makes them a goodtarget for using our methods of at-traction. In contrast, dispersal innonmigratory species often in-volves only a small percentage of thetotal population and can take placeover an extended time period(Greenwood & Harvey 1982). Thiscould make playbacks for non-mi-gratory species relatively inefficient.

Nocturnal singing. Several diur-nally active bird species call or singat night. Examples from NorthAmerica include marsh wren(Cistothorus palustris), sedge wren(Cistothorus platensis), northernmockingbird (Mimus polyglottos),yellow-breasted chat (Icterinavirens), and cuckoos (Coccyzus spp.)(Barclay et al. 1985; Merritt 1985;Walk et al. 2000). The function ofnocturnal singing in these specieshas not been determined, but onepossibility is that males sing to at-tract night-migrating females(Merritt 1985). Bird species inwhich males sing nocturnally maybe predisposed to settle at siteswhere they hear vocalizations dur-ing nighttime hours.

Clumped distributions. Manyterritorial birds show clumped dis-tributions in otherwise homoge-


neous habitats (reviewed in Stamps1988). Bird species known to clus-ter their territories include logger-head shrike (Lanius ludovicianus),house wren (Troglodytes aedon),acorn woodpecker (Melanerpesformicivorus), and least flycatcher(Empidonax minimus) (Burgess et al.1982; Muller et al. 1997; Etterson2003; Perry & Andersen 2003). Ob-viously, clumped distributionscould be caused by underlyingvariation in resource abundance orquality but in a few cases, authorshave been unable to find such varia-tion when they specifically lookedfor it (Etterson 2003; Perry &Andersen 2003). Clumped popu-lations in homogeneous environ-ments suggest that the birds sim-ply prefer to establish territoriesnear conspecifics.

Choosing Suitable HabitatSelecting appropriate species

and playback methods are only thefirst steps in establishing a newpopulation with conspecific attrac-tion. Perhaps the most importantconsideration for this technique isthat sites must be managed to en-sure that newly attracted birds cansurvive and reproduce well enoughto be a source population. Simplyattracting birds to a new site haslittle conservation value in itself;only if the population is productivewill this technique be a benefit tothe species. This was well demon-strated in our own research onblack-capped vireos. The mainthreat to the vireo is the brood-para-sitic brown-headed cowbird(Molothrus ater), which lays its eggsin vireo nests, reducing their pro-ductivity (U.S. Fish and WildlifeService 1991). Most of our researchsites were on government-ownedland at Fort Hood, Texas, wherecowbirds were controlled by shoot-

ing and trapping (Eckrich et al.1999). As a result, birds that wereattracted to playback sites in thisarea had low brood parasitism ratesand high nesting success (Ward &Schlossberg 2004). In contrast, atan experimental site on privateproperty where no cowbird controlwas undertaken, birds had highbrood parasitism rates and pro-duced no vireo young. This illus-trates the importance of active man-agement when using conspecificattraction.

Determining playback loca-tions can be difficult, and manyecological factors may affect thesuitability of a habitat. One factorthat should be considered whenusing conspecific attraction is thepotential for interactions betweenthe target species and other birdspecies in the area. Many birds areinterspecifically territorial, showingaggression towards another species(Sherry & Holmes 1988; Robinson& Terborgh 1995). In such cases,the presence of the competing spe-cies at playback sites could reducethe effectiveness of playbacks. Forinstance, in our research we foundthat black-capped vireos were dis-placed from some territories by thelarger, more aggressive Bell’s vireo(Vireo bellii).

Some knowledge of the targetspecies’ ecology can help to deter-mine which factors are likely tolimit its survival and reproductionat the playback site. Thus, westrongly suggest that managers beaware of the relevant literature de-scribing how avian demographyvaries with local and landscape-level habitat factors in their region.Census data can be used to selectsites that lack the potential competi-tors. To a great extent, managersmay be able to control limiting fac-tors by selecting appropriate sites.


Factors that can be controlled di-rectly include predators, broodparasites, diseases, and distur-bances (e.g. road or foot traffic).For instance, for forest-dwelling spe-cies, choosing large patches of habi-tat or extensively forested land-scapes should lead to reduced lev-els of nest predation and broodparasitism for songbirds (Wilcove1985; Robinson et al. 1995).

Establishing a PopulationIf playbacks attract birds to a

site, and they successfully repro-duce, managers must decidewhether to use conspecific attrac-tion in subsequent years. Assum-ing one’s goal is to establish a popu-lation that will persist over the longterm, there are two possible coursesof action. One could forgo play-backs and allow the birds attractedin the first year to return, sincemost birds show site fidelity afterreproducing successfully (Green-wood & Harvey 1982). On the otherhand, if the target species does nothave high site fidelity or has low re-productive success, few individualsmay return. This could create theneed to use playbacks in subse-quent years. For black-cappedvireos, we found that birds initiallyattracted to playback sites had rela-tively high site fidelity (approxi-mately 50%). In the second year ofour experiment, not knowing if thevireos would return, we used play-backs on some of our occupied sitesbut not on others. On all of the sites,there was little change in popula-tion sizes between the first and sec-ond years, suggesting that play-backs may be unnecessary to main-tain established populations (Wardand Schlossberg 2004).

ConclusionIf endangered birds use the

presence of conspecifics when de-termining where to settle, then theprotection or restoration of suitablehabitats may not be sufficient forthe site to be colonized. Birds mayavoid unoccupied habitat, hinder-ing recovery efforts (Scott et al.2001). In such cases, conspecific at-traction could be a significant tool,aiding in the recovery of bird popu-lations at suitable but unoccupiedsites. Several federally endangeredor candidate species (e.g. willow fly-catcher [Empidomax traillii], yel-low-billed cuckoo [Coccyzusamericanus], and golden-cheekedwarbler [Dendroica chrysoparia])exhibit behaviors that suggest con-specific attraction could be used intheir conservation.

Although conspecific attractionhas the potential to be an impor-tant tool for conservation, little dataexists on its prevalence in territo-rial birds. For conspecific attractionto be of value in the recovery of en-dangered species, it is importantthat managers have as much infor-mation on this behavior as possible.If, therefore, managers do attemptto use conspecific attraction as a toolin conservation, it is imperative thatboth positive and negative resultsbe published.

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Sherry, T. W. & R. T. Holmes. 1988. Habitatselection by breeding American redstarts inresponse to a dominant competitor, the leastflycatcher. Auk 105:350-364.

Sinclair, A. R. E. 1989. Population regulation inanimals. Pp. 197-241 in J. M. Cherrett, A. D.Bradshaw, F. B. Goldsmith, P. J. Grubb & J.R. Krebs, Eds, Ecological Concepts. BlackwellScientific Publications, Oxford.

Smith, A. T. & M. M. Peacock. 1990. Conspe-cific attraction and the determination ofmetapopulation recruitment rates. Conserva-tion Biology 4:320-323.

Stamps, J. A. 1987. Conspecifics as cues to ter-ritory quality: a preference of juvenile lizards(Anolis aeneus) for previously used territo-ries. American Naturalist 129:629-642.

Stamps, J. A. 1988. Conspecific attraction andaggregation in territorial species. AmericanNaturalist 131:329-347.

Stamps, J. A. 1991. The effects of conspecificson habitat selection in territorial species. Be-havioral Ecology and Sociobiology 28:29-36.

U.S. Fish and Wildlife Service. 1991. Black-capped Vireo (Vireo atricapillus) RecoveryPlan. Austin, Texas.

Walk, J. W., E. L. Kershner, & R. E. Warner.2000. Nocturnal singing in grassland birds.Wilson Bulletin 112:289-292.

Ward, M. P. & S. R. Schlossberg. 2004. Conspe-cific attraction and the conservation of territo-rial songbirds. Conservation Biology 18:519-525.

Weatherhead, P. J. & M. R. L. Forbes. 1994.Natal philopatry in passerine birds: Geneticor ecological influences? Behavioral Ecology5:426-433.

Wilcove, D. S. 1985. Nest predation in foresttracts and the decline of migratory songbirds.Ecology 66:1211-1214.


Puerto Rican Plain Pigeon FoodIntake in a Captive BreedingProgram

I.I. Aviles-Vasquez& K. Aviles-Vasquez*

*University of MichiganResidential College124 Green, East Quad1245Ann Arbor, MI 48109

Puerto Rican Plain Pigeon at the aviary of the Puerto Rican Plain PigeonProject, Humacao Campus of the University of Puerto Rico. Photo courtesy ofFr. Alejandro J. Sánchez Muñoz, Puerto Rico.


The Puerto Rican Plain Pigeon(Columba inornata wetmorei) is oneof the endangered species in the is-land of Puerto Rico. A captivebreeding program was establishedfrom 1984 to 2001 at the Univer-sity of Puerto Rico (UPR) HumacaoCampus as a way of combating thedecline of this species. The captivebreeding program in UPRHumacao had the objective of es-tablishing appropriate techniquesfor reproducing the species andproduce individuals to be freed inthe state forests. The captive pro-gram has been successful in its useof pigeon milk to feed thehatchlings by a surrogate mother orby hand. This led to the successfulbreeding of 44 pigeons in 1989, arecord in captive breeding pro-grams (Perez 2004). Despite thelongevity and successes of the pro-gram, specifics for this particularrace of plain pigeon are not wellknown. For the first time in thisstudy we measured the amount offeed that the pigeons consume incaptivity to determine their caloricintake and needs in case daily feedsare not available or illness arises inan individual.

The plain pigeon is the size of adomestic pigeon with a pale blue-gray color, and dark red beak andlegs. Historically, it was widespreadin the western foothills and valleysof Puerto Rico. General habitattypes used include lowland swampsand woodland, open woodland andcultivated land in the mountains,limestone karst, and coffee planta-tions in upland hills. The mainsource of food for the Plain Pigeonare day jasmine seeds (Cestrumdiurnum), but they also feed onroyal palm (Roystonea borinquena),mountain immortelle (Erythrinapoeppigiana), West Indies trema(Trema lamarckiana), and white

prickle (Zanthoxylum martinicense).(USFWS 2004)

Extensive destruction of natu-ral forest habitat and overhuntingare given as causes for the declineof the species. We can see this pat-tern manifested in the developmenthistory of Puerto Rico. By 1912,Puerto Rico had been largelycleared for agriculture and otherpurposes with one estimate placingthe amount of remaining forest atno more than 5,000 acres of virginor slightly-culled timber. By themiddle 1930s the plain pigeonpopulation was considered to be ex-tinct, until, in 1963, a populationwas rediscovered in the town ofCidra, also following the pattern offorest regrowth in the island. Stud-ies of that population between De-cember 1973 and September 1975attributed the majority of nest fail-ures observed to human-caused dis-turbances. Habitat loss due to therapid development of the Cidraarea is the most serious threat to thespecies’ existence. Though breedingoccurs throughout the year, thisspecies only lays one egg, and amaximum of 3 broods has been re-corded. This contributes to de-creased population growth when itsnesting areas are reduced everyyear. Furthermore, it is thoughtthat establishment of new popula-tions has been limited by the bird’sreluctance to colonize new areas.(USFWS 2004)

For this study, the diet for thecaptive individuals usually con-sisted of grains, supplemented withday jasmine (Cestrum diurnum)seeds, when in season. For the cap-tive program, the amount of feedwas determined based on the esti-mated protein and fat requirementsof the family Columbidae (Baer1984). However, such estimates arenot precise and despite of the lon-


gevity of the captive program, theexact dietary requirements of theplain pigeon and the effects of cap-tivity on its feeding behaviors arelargely unknown. As the nature ofcaptive programs make dailyfeedings difficult, insights into di-etary requirements of the plain pi-geon are critical, not only to evalu-ate the health of captive individu-als, but also to make necessary ad-justments to avoid food deficits.

Our objective was to determinethe average caloric intake of thePuerto Rican plain pigeon in cap-tivity. Each pigeon was kept in in-dividual cages, and we chose 8 in-dividuals for this study from thesmallest cages in the captive breed-ing project, due to ease of handling.The daily feed for the captive plainpigeons consisted of grains, con-taining 15% protein, 2.5% fat, and10.5% fiber, well within the rangeof proteins (12-28%), and fat(1%) suggested by Dierenfeld(Dierenfeld and Kreger 1992). Eachbird was given 45-55g of feed eachmorning in a marked cup. A smallcarton box was placed under eachcage to collect the feed spilled dur-ing the day. Unconsumed feed wascollected from the cup and the car-ton box and weighed each day be-tween 6 and 7pm to determine thedaily consumption of each of thebirds (the original weight of feedminus the weight of unconsumedfeed). To determine the daily ca-loric intake the weight of feed con-sumed was then converted to a ca-loric equivalent. This procedurewas repeated each day of everyother week from February throughApril in 2001.

We found that the captivePuerto Rican plain pigeon con-sumes an average of 11.425 gramsof feed daily or 54.383 cal. This av-erage daily caloric intake is consid-

erably smaller than the average forthe Columbidae family (Perez 2004).Approximately one third of the pi-geons would had no food intake fordays, despite readily available food,and when they did eat, it was invery small quantities. On average,the older plain pigeons ate muchless than expected under normalconditions for Columbidae.

Some possible reasons for theseresults are 1. Plain pigeons in cap-tivity eat less than pigeons in thewild because they don’t have tospend energy on flying, looking forfood, and/or mating rituals 2. Foodconsumption of the pigeons de-creases with age, and this was alikely factor in this study (pigeonson average were 10 years old). Fur-ther studies are needed to deter-mine if the effect of captivity, age,or an interaction of these two fac-tors caused the decrease in food in-take of the captive individuals. Po-tential future research may includemonitoring of wild individuals par-allel to a similar set-up of this studywith younger actively breeding cap-tive individuals. Further researchmay help us to better understandand improve the health of the cap-tive individuals and the success ofthe captive breeding program.

Agradecimientos al ex-personaldel ex-aviario de Humacao y aChristian Espinoza-Pino.

Literature Cited

Baer, David J. 1984. Animal Nutrition. To-ledo Zoological Society.

Dierenfeld, E.S. y M.D. Kreger. 1992. GuíaNutritiva y Dietética de los AnimalesSilvestres en Cautiverio. New York Zoo-logical Society. Pp. 31-32

Pérez, Raul. 2004. Director, University ofPuerto Rico Humacao Campus, PuertoRico: personal communication.

U.S. Fish and Wildlife Service. PuertoRican Plain Pigeon. Species accounts. Di-vision of Endangered Species. http://endangered.fws.gov/i/b/sab40.html (ac-cessed 1/Nov/04).


Book Review

Keepers of the Wolvesby Richard Thiel

Andrew Strassman

School of NaturalResources &EnvironmentUniversity of Michigan430 E. University

Ann Arbor, MI 48109


The proposed federaldelisting of Midwestern graywolves from the ESA

The status of the gray wolf, Ca-nis lupus, under the EndangeredSpecies Act (ESA) is currently un-der review. This short synopsis ofthe historical and current status ofthe species, with a focus on theMidwestern population, will re-view the proposed regulationchanges and delisting. The pro-posed rule changes are available onthe United States Fish and WildlifeService’s (USFWS) Region 3homepage (http://midwest.fws.gov/wolf/). Following this is a book re-view of Keepers of the Wolves, byRichard Thiel. This book makes afun, quick, and informative readon the reestablishment of the graywolf in Wisconsin.

Historically, the gray wolf wasfound throughout most of the con-tiguous United States and parts ofCentral Mexico, but was extirpatedsoon after European settlement inmost areas. The forests of theNortheastern United States and theUpper Midwest were the graywolf’s last refuges. The wolf popu-lation in the Northeast is believedto have been extirpated around1900 (Federal Register 69), whileWisconsin’s population was elimi-nated around 1958 (Thiel 2001).Minnesota maintained the only ex-tant population in the contiguousUS, as it remained connected to theCanadian wolf population.

Historically, there were severalsubspecies of gray wolf in NorthAmerica (Federal Register 69).There is also an ongoing debateabout whether the eastern timberwolf, Canis lupus lycaon, still exists,and if so, whether it is a subspeciesof the gray wolf or a separate spe-cies from Canis lupus (Wilson et al.2003). Currently, it is listed as a

subspecies of the gray wolf, but ifit is described as a separate speciesin the future, the listing status forboth the gray wolf and timber wolfcould be affected.

Today, the U.S. population ofgray wolves is limited to three dis-junct groups in the lower forty-eight: a population of gray wolvesin and around Yellowstone NationalPark, a population of Mexicanwolves, Canis lupus bailey, in Ari-zona and New Mexico, and a popu-lation of gray wolves in Minnesota,Wisconsin, and the Upper Penin-sula of Michigan. The populationsaround Yellowstone and in the Up-per Midwest are both connected tothe Canadian population, which isestimated at 44,000–51,000 indi-viduals, however, they are not di-rectly connected to each other(Musiani and Paquet 2004). Assuch, the ESA manages thesegroups separately without consid-eration of the Canadian animals asthe Act only applies to animals onUS soil. Alaska also supports a wolfpopulation of 7,500–10,000 indi-viduals that is not covered by theEndangered Species Act since thepopulation is not in danger(Musiani and Paquet 2004).

The gray wolf was listed as afederally endangered species in1967 by the USFWS and listedagain in 1974 when the ESA cameinto law (USFWS 2004). At thetime, gray wolf populations werelimited to northern Minnesota inthe contiguous US and believed,like the coyote and white-taileddeer, to need unfettered wildernessto survive. During gray wolfrecolonization of the Upper Mid-west, wolf biologists learned thatthis was not the case: the gray wolfis capable of living in human-dominated landscapes. In 1992,Mladenoff et al. estimated that

Figure 1. Wisconsin wolfpack locations and bound-aries, 1979. (Thiel 2001)

Figure 2. Wisconsin wolfpack locations and bound-aries, Winter 2003-04.(Wydeven and Wiedenhoeft,2004b)


Minnesota, Wisconsin, and theUpper Peninsula of Michigan har-bored over 94,000 km2 of forestthat had a greater than 50% prob-ability of being suitable gray wolfhabitat. A later study (Mladenoffet al. 1995) concluded that as thegray wolf population increased, sowould wolf use of substandardhabitat; this would then lead to in-creased contact of wolves with hu-mans and the associated problems.This statement is hard to quantify,because the majority of gray wolfinteractions with humans are neverreported. Evidence exists, however,to support the idea. The Wiscon-sin Department of Natural Re-sources (WIDNR) reported that 13cases of wolf depredation were re-ported in 2000, while 31 cases werereported in 2004 (Wydeven andWiedenhoeft 2000, 2004a). Addi-tionally, wolf sightings were re-ported in 30 Wisconsin counties in2000 and in 40 counties in 2004(Wydeven and Wiedenhoeft 2000,2004a). Finally, in 2003, 66 wolveswere found dead or had to be

euthanized in Wisconsin, morethan the estimated 1994 state wolfpopulation (Wydeven andWiedenhoeft 2000, 2004a).

Gray wolves naturally recolo-nized Wisconsin from Minnesotaand Canada in the mid-1970s andnaturally recolonized the UpperPeninsula of Michigan from Min-nesota and Wisconsin in the mid-1990s (Federal Register 69). In1979, shortly after recolonization ofWisconsin by the gray wolf, packlocations were limited to sparsely-roaded areas in the northern forestsof the state on, primarily, publicland (Figure 1). By 2003-2004, thegray wolf was found throughoutthe northern and central forests ofWisconsin on public, commercial,and private land. Wolves inhabitnot only remote areas, but also ar-eas in close proximity to denselypopulated urban and agriculturalcenters (Figure 2). Population andpack numbers have also increaseddramatically since recolonization inWisconsin, which suggests a con-tinued spread of wolves to areas ofnon-idyllic land in close proximityto humans (Figure 3).

Since 1974, gray wolf popula-tions have increased dramaticallythroughout the Upper Midwest.During the winter of 2003–04, Min-nesota had 3,020 wolves (Erb andBenson 2004), the Upper Peninsulaof Michigan had 360 wolves (upfrom zero in the early 1990’s), andWisconsin had 373 wolves (Figure3) (Federal Register 69). Thesenumbers represent healthy popu-lation levels in terms of the num-ber of individuals needed to sustainthe current density of wolves ac-cording to the state and federal re-covery plans. Additionally, in lateOctober 2004, a gray wolf collaredin the Upper Peninsula of Michi-gan was captured in a coyote trap

Figure 3. Gray wolf popula-tion and pack number in Wis-consin. Wydeven andWiedenhoeft, 2004b)


in the northern Lower Peninsula ofMichigan, the first since graywolves were extirpated in 1910(Matthews 2004).

In Wisconsin, the gray wolf waslisted as an endangered species in1975 (WIDNR 2004a). In 1989, thestate enacted a recovery plan for thegray wolf, which intended to havea state population of at least 80wolves over three consecutiveyears. If this goal was met, then thegray wolf would be considered forstate delisting (WIDNR 2004b). Theplan’s goal was met and then sur-passed by 1997 (Figure 3).

In Michigan, the gray wolf islisted as endangered. In 1997,Michigan enacted a gray wolf re-covery plan; at the time Michigan’sgray wolf population was 112 indi-viduals (excluding the Isle Royalepopulation) (Federal Register 69).The plan calls for a population of200 wolves over five consecutiveyears to consider the gray wolf re-covered in Michigan (Michigan1997). This goal was met and sur-passed in 2004 (Federal Register69).

The federal recovery plan forthe gray wolf in the Upper Midwest,as amended in 1992, called for twoseparate populations: the first wasa stable to growing population of1,251– 1,400 wolves in Minnesota;the second was either a) a popula-tion of greater than 100 wolves iflocated within 100-miles of theMinnesota population or b) a popu-lation of greater than 200 wolves iflocated greater than 100-milesfrom the Minnesota population.This second population had to bestable or growing for five consecu-tive years in order for the gray wolfto be considered for delisting(USFWS 1992). The 1992 federalplan estimated that wolf popula-

tions in the Upper Midwest wouldmeet this goal by 2005.

In 2000, federal gray wolf man-agement goals were modified tocoordinate population, habitat, andmanagement goals. Three distinctmanagement areas were created,each of which corresponds to anextant gray wolf population (Figure4). The currently considereddelisting plan affects only the East-ern Distinct Population Segment(EDPS), where the gray wolf is cur-rently listed as threatened (FederalRegister 68). It does not affect theWestern or Southern DistinctPopulation Segments (WDPS andSDPS). The WDPS includes botha population around YellowstoneNational Park (classified as a non-essential experimental population(NEP)), and a population along theCanadian border that is classifiedas threatened (Federal Register 68).The SDPS contains an NEP that ispart of an ongoing bi-national re-introduction program with Mexico(Federal Register 68).

In 1999, Wisconsin “down-listed” the gray wolf to a statethreatened species; federal down-listing in Wisconsin followed in

Figure 4. Federal gray wolfmanagement zones. (FederalRegister 69)


2000 (WIDNR 2004a). Other stateand federal listings differed becauseof state management plans andmanagement areas. In 1978, Min-nesota state and federally down-listed the gray wolf to threatened(MNDNR 2001). Michigan down-listed the gray wolf to threatenedin 2002 and it was federally down-listed in 2003 (MIDNR 2004).

The current proposed revisionof gray wolf ESA status asks forcomplete delisting of the gray wolfwithin the EDPS (Federal Register69). This would remove all federalprotection for the gray wolf withinonly the EDPS and leave furtherprotection to individual states andIndian tribes. The USFWS arguesthat this is warranted based on therecovery goals set forth in the 1992federal management plan (FederalRegister 69). These federal goalswere met in 1999, when the Wis-consin wolf population numberedover 100 wolves for a fourth year.Exceeding 700 individuals, thecurrent wolf population in theMichigan-Wisconsin region contin-ues to grow and appears to be ex-panding its range. The current statemanagement plans of Michigan,Minnesota, and Wisconsin wouldnot be legally affected by federaldelisting, which would ensure con-tinued protection of the gray wolfwithin state boundaries.

If delisting occurs, there will bea mandatory five-year monitoringperiod following delisting accord-ing to the ESA. This would be un-dertaken only in Michigan, Minne-sota, and Wisconsin, in conjunctionwith state monitoring (Federal Reg-ister 69). If during any period ofthe five-year monitoring “a signifi-cant downward change in thepopulations or an increase inthreats to the degree that popula-tion viability may be threatened”

are detected normal or emergencylisting can be undertaken (FederalRegister 69). After five years ofmonitoring, the gray wolf will bereevaluated, and at that time, it canbe considered for listing, continuedmonitoring, or discontinued moni-toring.

The period of public commenton delisting of the gray wolf closedon November 18th, 2004, 120 daysafter the original listing in the fed-eral register. The date of the finaldecision has not been released atpublishing.

In light of the proposed graywolf delisting from the EndangeredSpecies Act, I suggest readingKeepers of the Wolves. This book iswritten by Richard Thiel, a wolfbiologist for the Wisconsin Depart-ment of Natural Resources whowas closely involved in the reestab-lishment of the gray wolf in Wis-consin.

Keepers of the Wolves starts ap-proximately 20 years after the lastgray wolf was extirpated from Wis-consin in January of 1958. At thattime, the gray wolf once again hada chance, however slim, to survivein the state. One of the first peopleto see evidence of this return was ayoung Wisconsin Department ofNatural Resources (WIDNR) em-ployee named Richard Thiel. In hismemoir, Keepers of the Wolves, Thielrecalls over 20 years of joint effortto bring the gray wolf back fromthe brink of extinction. As a resultof these efforts, the gray wolf isundergoing the process of delistingfrom the Endangered Species Act(ESA). Based from Thiel’s own fieldnotes, memories, and contempo-rary conversations with past con-spirators, Keepers of the Wolves of-fers a refreshing perspective on thereestablishment of the gray wolf inWisconsin–that of a state wildlife


biologist who has interacted withthe wolves, public, and governmenton a daily basis (I’ll let him tell youwhich is the most dangerous).

Written for the general audi-ence, the first person narrative styledraws the reader right into the ac-tion and emotion of the story. Thereader gets to know the wolves,landscape, and people in the bookon a personal level. They will learnabout the tedium, disappointment,and frustration of the field as Dickfinds the third skunk of the day inthe trap-line and learns that hisfunding is (once again) inadequate.But the reader will also share theaccomplishments as Dick flies overa pack’s den site and discover sup-port from people he would leastexpect.

Keepers of the Wolves will also beinformative on the general process,problems, and excitement of spe-cies reintroduction. While the spe-cifics are those of the gray wolf inNorthern Wisconsin, the experi-ences Thiel relates will work as ex-amples to anyone interested in re-establishing threatened and endan-gered species. However, if you arelooking for a cookbook on charis-matic mega-fauna reintroduction,you will have to keep searching.

Keepers of the Wolves follows inthe footsteps of Aldo Leopold’s ASand County Almanac; by relatingpersonal experiences, Richard Thielbrings the interaction of wolves, theland, and the people together. Asin Leopold’s book, someone withany level of scientific indoctrinationcan read, understand, and enjoythis work. The scientific and fieldjargon are explained well; the writ-ing flows well and the illustrationsare helpful. Thiel covers numerousand various topics including wolf-deer ecology, basic animal tracking,wolf home territory mapping, and

how not to warm a frozen AMCRenault (the company car).

An important aspect of Keepersof the Wolves is that it is a quick andentertaining read on a very impor-tant and serious subject. The storyfollows the issues that surround thereestablishment of a historicallydenigrated large carnivore and pre-sents them in an honest, if at timesopinionated, manner. The graywolf is currently under review bythe United States Fish and WildlifeService for delisting from the En-dangered Species Act. Eventhough gray wolf populations haverebounded, they still face many ofthe same problems and threats aswhen they crossed into Wisconsinin the late 1970’s. Keepers of theWolves presents an entertaining re-view of these issues, especially inlight of the federal delisting of thegray wolf.

Keepers of the Wolves, by Rich-ard Thiel, is 227 pages long and isavailable through the University ofWisconsin Press.

Literature Cited

Erb, J. and Benson, S. (2004). Distributionand Abundance of Wolves in Minne-sota, 2003-04. Retrieved from Minne-sota Department of Natural Resourcesvia: http://files.dnr.state.mn.us/natural_resources/animals/mammals/wolves/2004_wolfsurvey_report.pdf(November 30, 2004).

Federal Register 68(62). (April 1, 2003). En-dangered and Threatened Wildlife andPlants; Final Rule To Reclassify and Re-move the Gray Wolf From the List ofEndangered and Threatened Wildlife inPortions of the Conterminous UnitedStates; Establishment of Two SpecialRegulations for Threatened GrayWolves. 15804-15875.

Federal Register 69(139). (July 21, 2004).Endangered and Threatened Wildlifeand Plants; Removing the Eastern Dis-tinct Population Segment of the GrayWolf From the List of Endangered and


Threatened Wildlife. 43664-43692.Matthews, G. (2004). Gray wolf found in

Northern Lower Peninsula. http://www.michigan.gov/dnr/0,1607,7-153—102934—,00.html (November 28, 2004).

Michigan, Department of Natural Re-sources (MIDNR). (2004). Gray Wolf(Canis lupus). http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12205-32569—,00.html (November 28, 2004).

Michigan, Department of Natural Re-sources (MIDNR). (1997). MichiganGray Wolf Recovery and ManagementPlan. Retrieved via MIDNR via: http://www.michigandnr.com/publications/p d f s / h u n t i n g w i l d l i f e h a b i t a t /wolf_mgmtplan.pdf (November 28,2004).

Minnesota, Department of Natural Re-sources (MNDNR). (2001). MinnesotaWolf Management Plan. Retrieved fromMNDNR via: http://files.dnr.state.mn.us/natural_resources/animals/mammals/wolves/wolfplan2000.pdf (November 30,2004).

Mladenoff, D. J., Sickley, T. A., Haight, R. G.and Wydeven, A. P. (1995). A RegionalLandscape Analysis and Predictions ofFavorable Gray Wolf Habitat in theNorthern Great Lakes Region. Conser-vation Biology, 9(2): 279-294.

Mladenoff, D. J., Sickley, T. A., andWydeven, A. P. (1999). Predicting GrayWolf Landscape Recolonization: Logis-tic Regression Models vs. New FieldData. Ecological Applications, 9(1): 37-44.

Musiani, M. and Paquet, P. C. (2004). ThePractices of Wolf Persecution, Protec-tion, and Restoration in Canada and theUnited States. BioScience, 54(1): 50-60.

Thiel, Richard. (2001). Keeper of theWolves: the early years of wolf recov-ery in Wisconsin. United States: Uni-versity of Wisconsin Press.

Wilson, P. J., S. Grewal, T. McFadden, R. C.Chambers, and B. N. White. (2003). “Mi-tochondrial DNA extracted from east-ern North American wolves killed in the1800’s is not of gray wolf origin.” Cana-dian Journal of Zoology, 81(5): 936-940.

Wisconsin, Department of Natural Re-sources (WIDNR). (2004a). Timber Wolf(Canis lupus). http://www.dnr.state.wi.us/org/land/er/factsheets/mammals/wolf.htm (No-vember 28, 2004).

Wisconsin, Department of Natural Re-sources (WIDNR). (2004b). WisconsinWolf Management Plan; October 27,1999. http://www.dnr.state.wi.us/org/

land/er/publications/wolfplan/toc.htm(November 28, 2004).

Wydeven, A. P. and J. E. Wiedenhoeft.(2000). Wisconsin Endangered Re-sources Report #119 Status of the tim-ber wolf inWisconsin Performance Report 1 July1999 through 30 June 2000. Retrieved from Wisconsin DNR via: http://www.dnr.state.wi.us/org/land/er/p u b l i c a t i o n s / r e p o r t s / W E R R %20Timber%20Wo l f / W E R R _ S t a t u s_of_Timber_Wolf_99-00.htm. (Novem-ber 28, 2004).

Wydeven, A. P. and J. E. Wiedenhoeft.(2004a). Wisconsin Endangered Re-sources Report #________ Status of thetimber wolf in Wisconsin PerformanceReport 1 July 2003 – 30 June 2004. Re-trieved from Wisconsin DNR via:http://www.dnr.state.wi.us/org/land/er/publications/reports/WERR%20T i m b e r % 2 0 Wo l f / W E R R _ S t a t u s_of_Timber_Wolf_03-04.htm (November28, 2004).

Wydeven, A. P. and J. E. Wiedenhoeft.(2004b). Wisconsin Endangered Re-sources Report #________ Status of thetimber wolf in Wisconsin PerformanceReport 1 July 2003 – 30 June 2004, Fig-ures. Retrieved from Wisconsin DNR, :h t t p : / / w w w. d n r. s t a t e . w i . u s / o r g /land/er/publications/reports/WERR%20Timber%20Wolf/TimberWolf_PDFs/W E R R _ T i m b e r _ Wo l f _ S t a t u s 0 3 -04Figures.pdf (November 28, 2004).

U.S. Fish and Wildlife Service. (1992). Re-covery Plan for the Eastern Timber Wolf.Retrieved from USFWS via: http://midwest.fws.gov/wolf/recovery/recov-plan.pdf (November 28, 2004)

U.S. Fish and Wildlife Service. (2004).Wolf, gray.https://ecos.fws.gov/s p e c i e s _ p r o f i l e/SpeciesProfile?spcode=A00D (Novem-ber 28, 2004).


FOCUS ON NATURE TM by Rochelle Mason

The chicks sure are growing fast thinks the LEAST BELL’S VIREO

(Vireo bellii pusillus). Instead of raising 3 small, delicate chicks sheis caring for 3 giant, voracious chicks. Its happened again. Thesechicks are brown-headed cowbirds. The cowbird parents trickedthe vireo into raising their young. This is a problem for the endan-gered vireo’s survival but a brilliant strategy for the prolific cow-bird. The nearly-exhausted female leaves her nest in search of yetanother meal. She flits around in the dense, riparian foliage grow-ing along the Amargosa River here in Inyo County, California. Awiggling larva on a leaf of a willow tree catches her eye and isquickly consumed. When maternal responsibilities are over andthe signals of changing seasons approach, the least Bell’s vireos willfly to warmer climes south of the border to relax. Artwork and textby Rochelle Mason. Copyright 1998-2003 www.rmasonfinearts.com(808) 985-7311


The Endangered Species UPDATE is committed to advancing science, policy, and interdisciplinary issues relatedto species conservation, with an emphasis on rare and declining species. The UPDATE is a forum for informationexchange on species conservation, and includes a reprint of the U.S. Fish and Wildlife Service's Endangered SpeciesTechnical Bulletin, along with complementary articles relaying conservation efforts from outside the federal pro-gram.

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3. Technical Notes/Reports from the Field — ongoing research, application of conservation biology tech-niques, species conservation projects, etc., at the local, state, or national level. These are approximately 750 words(3 double spaced typed pages).

4. Species at Risk — profiles of rare and declining species, including the following information: taxonomy,distribution, physical characteristics, natural/life history, conservation status, and economic importance. Theseprofiles are approximately 750-1500 words (3 to 6 double spaced typed pages).

5. Book Reviews — reviews should include such information as relevant context and audience, and analysisof content. Reviews are approximately 750-1250 words (3 to 5 double spaced typed pages). Please contact theeditor before writing a book review.

6. Bulletin Board — submissions of news items that can be placed on the back page. These items can includemeeting notices, book announcements, or legislative news, for example.

Manuscript Submissions and SpecificationsSubmit the manuscript to:Editor, Endangered Species UPDATESchool of Natural Resources and EnvironmentUniversity of Michigan430 E. UniversityAnn Arbor, MI 48109-1115

Instructions to Authors


Subscribe to the UPDATE today!In its 21 years of publication, the Endangered Species UPDATE, published bythe School of Natural Resources and Environment at the University ofMichigan, has established itself as the primary forum for governmentagencies, conservation organizations, private consulting and law firms,zoos, museums, educational institutions, and others to exchange ideas andinformation on species conservation issues.

Subscription rates are: Institutions $78individual subscriptions $33student/senior (65+) $25address outside the US add $5

electronic subscription $20

To subscribe, make check payable to the University of Michigan and mailto: Endangered Species UPDATE School of Natural Resources and Environment The University of Michigan 430 E. University Ann Arbor, MI 48109-1115

or visit our website: http://www.umich.edu/~esupdate

To submit your manuscript electronically, e-mail the manuscript as a Word file or rich formatted text (.rft)attachment to: [email protected].

Manuscripts should be typed, double-spaced, with ragged right margins to reduce the number of end of linehyphens. Print must be in upper- and lower-case letters and of typewriter quality. Metric measurements mustbe given unless English measurements are more appropriate, in which case metric equivalents must be given inparentheses. Statistical terms and other measures should conform to the Council of Biology Editors Style Manual.All pages should be numbered. Manuscripts must be in English.

Initial acceptance of a proposal or manuscript does not guarantee publication. After initial acceptance,authors and editors work closely on all revisions before a final proof is agreed upon.

Citations, Tables, Illustrations, and PhotographsLiterature citations in the text should be as follows: (Buckley and Buckley 1980b; Pacey 1983). For abbreviationsand details consult the Editor and recent issues of the Endangered Species UPDATE.

Illustrations and photographs may be submitted as electronic documents or as hard copies. If hard copiesare submitted, the author's name and the figure number should be penciled on the back of every figure. Letteringshould be uniform among figures. All illustrations and photos should be clear enough to be reduced 50 percent.Please note that the minimum acceptable resolution for all digital images is 300dpi.

Author credit instructions for each author of the article should accompany the manuscript.

Policy on Reviewing ProofsAuthors are asked to do the final copy editing of their articles. It is in the authors' power to save themselves andthe journal the embarrassment of having to explain mistakes that could have been avoided.

Contents Volume 21 No. 4 2004

119 Guidelines for Developing StatusDeterming Criteria

Kim E.W. Shelden& Douglas P. DeMaster

124 Rodent Pest Control Through the Re-Introduction of an Extirpated RaptorSpecies


128 Amphibian Conservation Strategies:Translocating an Entire Population ofBlanchard's Cricket Frog (Acris crepitansblanchardi) in southeast Michigan

Ariana Rickard, Edi Sonntag, &Kevin Zippel

132 Using Conspecific Attraction to ConserveEndangered Birds

Scott R. Schlossberg &Michael P. Ward

139 Puerto Rican Plain Pigeon Food Intake in aCaptive Breeding Program

I.I. Aviles-Vazquez,& K.R. Aviles-Vazquez

142 Book Review: Keepers of the WolvesAndrew Strassman

119 Directivas por el desarrollo de criterios que

determinan el estado de especies

Kim E.W. Shelden& Douglas P. DeMaster

124 El control de roedores con la re-introducción

de una especie de búho


128 La conservación de especies de anfibios:La translocacion de una poblacion enteradel Blanchard Cricket Frog (Acris crepitansblanchardi)en el sureste de Michigan

Ariana Rickard, Edi Sonntag, &Kevin Zippel

132 El uso de la atracción de coespecies paraconservar pájaros en peligro de extinción

Scott R. Schlossberg &Michael P. Ward

139 La admisión de comida en elpuertorriqueño paloma en un programade criar en cautividad

I.I. Aviles-Vazquez,& K.R. Aviles-Vazquez

142 Critica de Libros: Guardián de los LobosAndrew Strassman

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