Digital Commons Network^™

Prey-Mediated Avoidance Of An Intraguild Predator By Its Intraguild Prey, Ryan R. Wilson, Terry L. Blankenship, Mevin B. Hooten, John Shivik

United States Department of Agriculture Wildlife Services: Staff Publications

Intraguild (IG) predation is an important factor influencing community structure, yet factors allowing coexistence of IG predator and IG prey are not well understood. The existence of spatial refuges for IG prey has recently been noted for their importance in allowing coexistence. However, reduction in basal prey availability might lead IG prey to leave spatial refuges for greater access to prey, leading to increased IG predation and fewer opportunities for coexistence. We determined how the availability of prey affected space-use patterns of bobcats (Lynx rufus, IG prey) in relation to coyote space-use patterns (Canis latrans, IG …

Reporting Difference For Colored Patagial Tags On Ring-Billed Gulls, Thomas W. Seamans, Scott F. Beckerman, John W. Hartmann, James A. Rader, Bradley F. Blackwell

United States Department of Agriculture Wildlife Services: Staff Publications

The possible role of tag color in mediating behaviors that could bias resighting rate has not been examined. In a study that began in 2007, we marked 725 ring-billed gulls (Larus delawarensis) with Bondcote royal blue, green, yellow, or orange patagial tags. Reports we gathered over 2 years indicated approximately a 3.4:1 bias in resighting rate toward yellow or orange tags. The observed bias is inconsistent with color-associated visibility bias or differential mortality among color-tagged breeding adults. Potential behavioral effects of tag color on individuals and conspecifics should be considered by biologists when planning marking studies.

Epizootic Hemorrhagic Disease Outbreak In A Captive Facility Housing White-Tailed Deer (Odocoileus Virginianus), Bison (Bison Bison), Elk (Cervus Elaphus), Cattle (Bos Taurus), And Goats (Capra Hircus) In Colorado, Usa, Pauline Nol, Cecilia Kato, Will K. Reeves, Jack Rhyan, Terry R. Spraker, Thomas Gidlewski, Kurt C. Vercauteren, Mo Salman

United States Department of Agriculture Wildlife Services: Staff Publications

An ungulate research facility in Fort Collins, Colorado, USA, experienced mortality in white-tailed deer (Odocoileus virginianus) because of epizootic hemorrhagic disease virus (EHDV) infection from 20 August 2007 through 26 September 2007. Epizootic hemorrhagic disease virus (EHDV) was detected by reverse transcriptase polymerase chain reaction and virus isolation from the spleen and lung tissues of two white-tailed deer. Virus neutralization tests were performed on pre- and post-outbreak sera from other species maintained in the same facility, including bison (Bison bison), elk (Cervus elaphus), domestic cattle (Bos taurus), and domestic goats (Capra hircus), …

Utility Of Livestock-Protection Dogs For Deterring Wildlife From Cattle Farms, Thomas M. Gehring, Kurt C. Vercauteren, Megan L. Provost, Anna C. Cellar

United States Department of Agriculture Wildlife Services: Staff Publications

Context. Livestock producers worldwide are negatively affected by livestock losses because of predators and wildlife transmitted diseases. In the western Great Lakes Region of the United States, this conflict has increased as grey wolf (Canis lupus) populations have recovered and white-tailed deer (Odocoileus virginianus) have served as a wildlife reservoir for bovine tuberculosis (Myobacterium bovis).

Aims. We conducted field experiments on cattle farms to evaluate the effectiveness of livestock-protection dogs (LPDs) for excluding wolves, coyotes (C. latrans), white-tailed deer and mesopredators from livestock pastures.

Methods. We integrated LPDs on …

Management Of Damage By Elk (Cervus Elaphus) In North America: A Review, W. David Walter, Michael J. Lavelle, Justin W. Fischer, Therese L. Johnson, Scott E. Hygnstrom, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Abundant populations of elk (Cervus elaphus) are cherished game in many regions of the world and also cause considerable human–wildlife conflicts through depredation on agriculture and specialty crops, lack of regeneration to native ecosystems, collisions with vehicles and transmission of disease between free-ranging and farmed hoofstock. Management of elk varies, depending on current and historical agency objectives, configuration of the landscapes elk occupy, public perception, population density and behaviour of elk. Selection of the method to manage elk often requires knowledge of timing of impacts, duration relief from elk damage is desired, cost-effectiveness of management activities, tolerance of …

Laboratory Efficacy Of Chemical Repellents For Reducing Blackbird Damage In Rice And Sunflower Crops, Scott J. Werner, George M. Linz, Shelagh K. Tupper, James C. Carlson

United States Department of Agriculture Wildlife Services: Staff Publications

Nonlethal alternatives are needed to manage blackbird (Icterids) damage to rice and sunflower production in the United States. We evaluated 4 registered fungicides on rice seeds (i.e., Allegiance^® FL, Thiram 42-S, Trilex^®, and Vitavax^® 200 preplant seed treatments) and 2 foliar pesticides on sunflower seeds (Cobalt^TM insecticide and Flock Buster bird repellent) as candidate blackbird repellents. Red-winged blackbirds (Agelaius phoeniceus) preferred untreated rice relative to rice treated with Thiram (P < 0.001) and Vitavax (P < 0.001), and untreated sunflower relative to sunflower treated with Cobalt (P < 0.001). Blackbirds preferred untreated sunflower relative to sunflower treated with Flock Buster repellent on day 1 of a 4-day preference test (P < 0.001). We observed no difference in consumption of treated versus untreated rice during the Allegiance preference test (P = 0.928), and blackbirds preferred rice treated with Trilex relative to untreated rice (P = 0.003). Although …

Assessing Potential Risk To Alligators, Alligator Mississippiensis, From Nutria Control With Zinc Phosphide Rodenticide Baits, Gary W. Witmer, John D. Eisemann, Thomas M. Primus, Jeanette R. O’Hare, Kelly R. Perry, Ruth M. Elsey, Phillip L. Trosclair Iii

United States Department of Agriculture Wildlife Services: Staff Publications

Nutria, Myocastor coypus, populations must be reduced when they cause substantial wetland damage. Control can include the rodenticide zinc phosphide, but the potential impacts to American alligators, Alligator mississippiensis, must be assessed. The mean amount of zinc phosphide per nutria found in nutria carcasses was 50 mg. Risk assessment determined that a conservative estimate for maximum exposure would be 173 mg zinc phosphide for a 28 kg alligator, or 6.2 mg/kg. Probit analysis found an LD₅₀ for alligators of 28 mg/kg. Our studies suggest that the use of zinc phosphide to manage nutria populations would pose only …

Rodent Outbreaks In North America, Gary W. Witmer, Gilbert Proulx

United States Department of Agriculture Wildlife Services: Staff Publications

Fluctuations in rodent population densities in North America are a reality. Our understanding of the factors causing such fluctuations is incomplete; therefore, it is important to monitor populations to increase our understanding of natural wildlife communities so as to avoid substantial damage to agriculture, forestry, and urban infrastructures, and to prevent rodent-borne disease transmission to humans. There is a need to establish integrated pest management programs in which monitoring, preventive cultural practices, and various control methods (mechanical, physical, biological, and chemical) are strategically coordinated to maintain rodent population densities at acceptable pest levels.

Sustained Agricitlture: The Need To Manage Rodent Damage, Gary W. Witmer, Grant R. Singleton

United States Department of Agriculture Wildlife Services: Staff Publications

The need for sustained agricultural production increases as the world's human population increases, many natural resources grow scarce, and the amount of land devoted to agriculture declines. For example, Vietnam loses 30,000 ha annually of prime lice land to urban development, yet it is the second highest exporter of rice in a world market that reached crisis levels during 2008 (Meerburg et al, 2009b), Between 1960 and 2000, the world's population doubled; in Asia alone the annual population growth until 2020 is estimated at 75 million, which is a lot of new mouths to feed (FAO, 2008). Hence, feeding …

Observations Of Neck-Collared Canada Geese Near John F. Kennedy International Airport, New York, Thomas W. Seamans, Scott E. Clemons, Allen L. Gosser

United States Department of Agriculture Wildlife Services: Staff Publications

Canada geese (Branta canadensis) often cause significant damage when they strike aircraft. They are responsible for a reported minimum of $2.6 million in damage per year to civil aviation in the United States. Knowledge of goose movements in relation to airports would allow wildlife managers to allocate time and funds to manage those populations that pose the greatest threat to aircraft. We placed alpha-numeric neck collars on 300 Canada geese within 8 km of both John F. Kennedy International Airport (JFKIA) and LaGuardia Airport in New York, New York. We conducted weekly observations for 2 years within a …

Detection Of Protease-Resistant Cervid Prion Protein In Water From A Cwd-Endemic Area, T. A. Nichols, Bruce Pulford, A. Christy Wyckoff, Crystal Meyerett, Brady Michel, Kevin Gertig, Edward A. Hoover, Jean E. Jewell, Glenn C. Telling, Mark D. Zabel

United States Department of Agriculture Wildlife Services: Staff Publications

Chronic wasting disease (CWD) is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. Although the exact mode of natural transmission remains unknown, substantial evidence suggests that prions can persist in the environment, implicating components thereof as potential prion reservoirs and transmission vehicles. CWD-positive animals may contribute to environmental prion load via decomposing carcasses and biological materials including saliva, blood, urine and feces. Sensitivity limitations of conventional assays hamper evaluation of environmental prion loads in soil and water. Here we show the ability of serial protein misfolding cyclic amplification (sPMCA) to amplify a 1.3 x 10^-7 dilution of CWD-infected …

Tactics And Economics Of Wildlife Oral Rabies Vaccination, Canada And The United States, Ray T. Sterner, Martin I. Meltzer, Stephanie A. Shwiff, Dennis Slate

United States Department of Agriculture Wildlife Services: Staff Publications

Progressive elimination of rabies in wildlife has been a general strategy in Canada and the United States; common campaign tactics are trap–vaccinate–release (TVR), point infection control (PIC), and oral rabies vaccination (ORV). TVR and PIC are labor intensive and the most expensive tactics per unit area (≈$616/km² [in 2008 Can$, converted from the reported $450/km² in 1991 Can$] and ≈$612/km² [$500/km² in 1999 Can$], respectively), but these tactics have proven crucial to elimination of raccoon rabies in Canada and to maintenance of ORV zones for preventing the spread of raccoon rabies in the United States. Economic …

Spatial Ecology Of Raccoons Related To Cattle And Bovine Tuberculosis In Northeastern Michigan, Todd C. Atwood, Thomas J. Deliberto, Holly J. Smith, Justin S. Stevenson, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

In 1995, Mycobacterium bovis, the causative bacterium of bovine tuberculosis (bTB), was detected in 5 beef cattle operations in Alcona County, Michigan, USA. In accordance with Federal law, the operations were depopulated to prevent the spread of bTB. Subsequent wildlife surveillance programs identified high prevalence of M. bovis in mesocarnivores, including raccoons (Procyon lotor), which suggested that raccoons may be complicit in vectoring the pathogen among livestock operations. Our goal was to develop an empirical basis for generating hypotheses about the likelihood for raccoons to mediate the transmission of bTB to livestock. We found intersexual differences in scale-dependent …

Deer Guards And Bump Gates For Excluding White-Tailed Deer From Fenced Resources, Kurt C. Vercauteren, Nathan Seward, Michael J. Lavelle, Justin W. Fischer, Gregory Phillips

United States Department of Agriculture Wildlife Services: Staff Publications

White-tailed deer (Odocoileus virginianus) causing damage is a reoccurring theme in the realm of wildlife damage management, especially regarding human safety, disease transmission, and agricultural losses. Fences often are the only reliable long-term nonlethal means of controlling deer damage. The efficacy of fences, however, relies on their weakest link: human-operated gates. Although not overly time-consuming, the act of closing a gate appears to be a burden to individuals, resulting in open-access to an otherwise protected resource. We examined the efficacy of 2 alternatives to traditional gates to evaluate their potential to be used for excluding or containing deer. …

Translocation Of Nine-Banded Armadillos, Daniel J. Gammons, Michael Mengak, L. Michael Conner

United States Department of Agriculture Wildlife Services: Staff Publications

During the last 150 years, nine-banded armadillos (Dasypus novemcinctus) have increased their range and abundance in the southeastern United States. When foraging, armadillos cause damage to agricultural crops as, as well as cause structural damage to driveways and foundations. Homeowners frequently use translocation to reduce local armadillo abundance. Despite its popularity with the general public, however, the appropriateness of nuisance wildlife translocation presents concerns for biologists. Our objective was to address some of these concerns by examining survival and movements of translocated armadillos. We translocated 12 armadillos (9 male, 3 female) equipped with radio-transmitters and compared their survival …

White-Tailed Deer Browsing And Rubbing Preferences For Trees And Shrubs That Produce Nontimber Forest Products, Scott E. Hygnstrom, Peter D. Skelton, Scott J. Josiah, Jason M. Gilsdorf, Dallas R. Virchow, James A. Brandle, Anil K. Jayaprakash, Kent M. Eskridge, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Nontimber forest products (food, herbal medicinals, and woody floral and handicraft products) produced in forest, agroforestry, and horticultural systems can be important sources of income to landowners. White-tailed deer (Odocoileus virginianus) can reduce the quality, quantity, and profitability of forest products by browsing twigs and rubbing stems, resulting in direct and indirect losses to production enterprises. We evaluated deer damage (frequency and intensity of browsing and rubbing) sustained by 26 species of trees and shrubs, the relationships among morphological features of trees and shrubs to damage levels, and the economic impacts of deer damage on the production of …

Evaluation And Development Of Blackbird Repellents For Agricultural Applications, Scott J. Werner, Shelagh Tupper, George M. Linz, H. Jeffrey Homan

United States Department of Agriculture Wildlife Services: Staff Publications

We evaluated several registered fungicides and insecticides, and several natural compounds as candidate blackbird repellents for protecting agricultural production. We tested more than 750 red-winged blackbirds at the National Wildlife Research Center’s outdoor animal research facility in Fort Collins, CO to evaluate (1) their preference for treated versus untreated rice and sunflower seeds and (2) their consumption of seeds treated with varying concentrations of candidate repellents. Concentrations were varied between 10% and 200% of labeled application rates. With few exceptions, blackbirds discriminated between untreated seeds and seeds treated with one of the candidate repellents. We observed greatest repellency with caffeine …

Experimental Infection Of Richardson’S Ground Squirrels (Spermophilus Richardsonii ) With Attenuated And Virulent Strains Pf Brucella Abortus, Pauline Nol, Steven C. Olsen, Jack C. Rhyan

United States Department of Agriculture Wildlife Services: Staff Publications

A previous investigation of the safety of Brucella abortus strain RB51 (sRB51) in various nontarget species suggested that Richardson’s ground squirrels (Spermophilus richardsonii) may develop persistent infections when orally inoculated with the vaccine. In the present study, sRB51, B. abortus strain 19 (s19), and virulent B. abortus strain 9941 (s9941) were administered orally to Richardson’s ground squirrels to further characterize B. abortus infection in this species. Six groups of nongravid ground squirrels were orally inoculated with 6x10⁸ colony forming units (cfu) sRB51 (n=10), 2.5x10⁴ cfu s19 (n=10), 2.5x10⁷ cfu s19 (n=6), 1.3x10⁶ cfu s9941 …

Managing Predators To Protect Endangered Species And Promote Their Successful Reproduction, Richard M. Engeman, Bernice Constantin, Kenneth S. Gruver, Corey Ross

United States Department of Agriculture Wildlife Services: Staff Publications

Predation critically threatens many rare species, with the deleterious impacts of predation losses compounded by habitat loss. Predators of endangered species are frequently invasive species or artificially over-abundant native species. Often, predation is most damaging to a species' ability to reproduce. We use examples from the tropics to the tundra with which we have been involved to demonstrate how predator management can be a highly effective and economically efficient means to protect populations of rare species and enhance their reproduction.

Landscape-Genetic Analysis Of Population Structure In The Texas Gray Fox Oral Rabies Vaccination Zone, Randy Deyoung, Angeline Zamorano, Brian Mesenrink, Tyler A. Campbell, Bruce Leland, Guy Moore, Rodney Honeycutt, J. Jeffrey Root

United States Department of Agriculture Wildlife Services: Staff Publications

In west-central Texas, USA, abatement efforts for the gray fox (Urocyon cinereoargenteus) rabies epizootic illustrate the difficulties inherent in large-scale management of wildlife disease. The rabies epizootic has been managed through a cooperative oral rabies vaccination program (ORV) since 1996. Millions of edible baits containing a rabies vaccine have been distributed annually in a 16-km to 24-km zone around the perimeter of the epizootic, which encompasses a geographic area >4 x 10⁵ km². The ORV program successfully halted expansion of the epizootic into metropolitan areas but has not achieved the ultimate goal of eradication. Rabies …

Escherichia Coli, Salmonella, And Mycobacterium Avium Subsp. Paratuberculosis In Wild European Starlings At A Kansas Cattle Feedlot, Shannon M. Gaukler, George M. Linz, Julie S. Sherwood, Neil W. Dyer, William J. Bleier, Yvonne M. Wannemuehler, Lisa K. Nolan, Catherine M. Logue

United States Department of Agriculture Wildlife Services: Staff Publications

The prevalence of Escherichia coli, Salmonella spp., and Mycobacterium avium subsp. paratuberculosis isolated from the feces of wild European starlings (Sturnus vulgaris) humanely trapped at a feedlot in central Kansas was assessed. All E. coli and Salmonella isolates recovered were tested for antimicrobial susceptibility using National Antimicrobial Resistance Monitoring System panels and the E. coli isolates were classified as to their content of genes associated with pathogenic E. coli of birds and cattle, including cvaC, iroN2, ompTp, hlyF2, eitC, iss, iutA, ireA, papC, stxI, stxII, sta, K99, F41, and eae. Escherichia coli O157:H7 and Mycobacterium avium …

Avian Use Of Harvested Crop Fields In North Dakota During Spring Migration, Alegra M. Galle, George M. Linz, H. Jeffrey Homan, William J. Bleier

United States Department of Agriculture Wildlife Services: Staff Publications

Broad-spectrum herbicide applications and improved harvesting efficiency of crops have reduced the availability of weed seeds and waste grains for game and nongame wildlife. Over the last decade, corn and soybean plantings have steadily increased in the Prairie Pothole Region (PPR) of North Dakota, while sunflower plantings have declined. The PPR is an important corridor for migratory birds, and changes in food availabilities at stopover habitats may affect how food resources are used. In early spring 2003 and 2004, we compared bird use of harvested fields of sunflower, soybeans, small grains, and corn in the PPR of North Dakota. Across …

Evaluating New Protein Sources For Development Of A Deer Repellent Product, Bruce A. Kimball, Kelly R. Perry

United States Department of Agriculture Wildlife Services: Staff Publications

Several protein sources were tested as deer repellents with captive deer. Black-tailed deer were offered Western redcedar seedlings treated with corn gluten meal, feather meal, poultry blood, hydrolyzed casein, or a control (latex sticker used for treatment proteins). After 37 days, feather meal and hydrolyzed casein provided equivalent protection against browse damage (only 23% of seedlings significantly browsed). Poultry blood provided less browse protection (44% browsed), while browse damage to seedlings treated with corn gluten meal (73% browsed) was not statistically different than the control (100% browsed). Based on the efficacy of feather meal and its low material cost, this …

Predator And Heterospecific Stimuli Alter Behavior In Cattle, Bryan M. Kluever, Larry D. Howery, Stewart W. Breck, David L. Bergman

United States Department of Agriculture Wildlife Services: Staff Publications

Wild and domestic ungulates modify their behavior in the presence of olfactory and visual cues of predators but investigations have not exposed a domestic species to a series of cues representing various predators and other ungulate herbivores.We used wolf (Canis lupus), mountain lion (Puma concolor), and mule deer (Odocoileus hemionus) stimuli (olfactory and visual), and a control (no stimuli) to experimentally test for differences in behavior of cattle (Bos taurus) raised in Arizona. We measured (1) vigilance, (2) foraging rates, (3) giving up density (GUD) of high quality foods and (4) time …

Physiological Stress Response Of Captive White-Tailed Deer To Video Collars, Remington Moll, Joshua J. Millspaugh, Jeff Beringer, Joel Sartwell, Rami Woods, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Animal-borne video and environmental data collection systems (AVEDs) are an advanced form of biotelemetry that combines video with other sensors. As a proxy for physiological stress, we assessed fecal glucocorticoid metabolite (FGM) excretion in 7 white-tailed deer (Odocoileus virginianus) fitted with AVED dummy collars; 9 additional deer served as controls. We collected fecal samples over 3 2-week periods: pretreatment, treatment, and post-treatment periods. There were no differences in FGMs across time periods (F_2,218 = 1.94, P = 0.147) and no difference between FGMs of control and treatment individuals (F_1,14 = 0.72, P = 0.411). Fecal glucocorticoid …

Monitoring Exposure To Avian Influenza Viruses In Wild Mammals, Kaci K. Vandalen, Susan A. Shriner, Heather J. Sullivan, J. Jeffrey Root, Alan B. Franklin

United States Department of Agriculture Wildlife Services: Staff Publications

1. Avian influenza (AI) viruses primarily circulate in wild waterfowl populations and are occasionally transmitted to domestic poultry flocks. However, the possible roles of other wildlife species, such as wild mammals, in AI virus ecology have not been adequately addressed.

2. Due to their habitat and behavior, many wild mammals may be capable of transmitting pathogens among wild and domestic populations. Exposure to AI viruses has been reported in an array of wild and domestic animals. The presence of wild mammals on farms has been identified as a risk factor for at least one poultry AI outbreak in North America. …

Pathogenesis And Epidemiology Of Brucellosis In Yellowstone Bison: Serologic And Culture Results From Adult Females And Their Progeny, Jack C. Rhyan, Keith Aune, Thomas Roffe, Darla Ewalt, Steve Hennager, Tom Gidlewski, Steve Olsen, Ryan Clarke

United States Department of Agriculture Wildlife Services: Staff Publications

Our objective in this prospective study was to determine the natural course of Brucella abortus infection in cohorts of seropositive and seronegative, female bison (Bison bison) and their offspring in Yellowstone National Park (YNP) for 5 yr. We collected specimens from 53 adult females and 25 calves at least once and from 45 adults and 22 calves more than once. Annual seroconversion rates (negative to positive) were relatively high (23% for calves and juvenile bison, 6% in the total sample of adult female bison in our study, and 11% in the adult females that began the study as …

Wildlife Collisions With Aircraft: A Missing Component Of Land-Use Planning For Airports, Bradley F. Blackwell, Travis L. Devault, Esteban Fernández-Juricic, Richard A. Dolbeer

United States Department of Agriculture Wildlife Services: Staff Publications

Projecting risks posed to aviation safety by wildlife populations is often overlooked in airport land-use planning. However, the growing dependency on civil aviation for global commerce can require increases in capacity at airports which affect land use, wildlife populations, and perspectives on aviation safety. Our objectives were to (1) review legislation that affects airports and surrounding communities relative to managing and reducing wildlife hazards to aviation; (2) identify information gaps and future research needs relative to regulated land uses on and near airports, and the effects on wildlife populations; and (3) demonstrate how information regarding wildlife responses to land-use practices …

Effects Of A Synthetic Gonadotrophin-Releasing Hormone Agonist, Leuprolide, On Rut-Associated Events In Male Red Deer, G. K. Barrell, S. C. T. Schaafsma, M. J. Ridgway, M. Wellby, L. A. Miller

United States Department of Agriculture Wildlife Services: Staff Publications

This study examined the effectiveness of leuprolide, a gonadotrophin-releasing hormone agonist, in suppressing rut-associated events in farmed male red deer. In mid-January (~6 weeks before the rut period in the southern hemisphere) adult red deer (Cervus elaphus scoticus) stags that had been allocated to three groups (n = 10 per group) received leuprolide, administered subcutaneously in a 90-day release formulation, at zero (control), low (22.5 mg) or high (45 mg) doses. Following treatment with leuprolide there was evidence of suppression of mean plasma luteinising hormone concentration that was significant (P < 0.05) at 9 weeks. Mean plasma testosterone concentration of all three groups rose following treatment, then declined prematurely in the low- and high-dose leuprolide-treated groups, so that it was significantly (P < 0.05) suppressed (0.66 ± 0.29 and 2.0 ± 0.88 ng mL^–1, low and high dose respectively) in …

Assessing Allowable Take Of Migratory Birds, Michael Runge, John Sauer, Michael L. Avery, Bradley F. Blackwell, Mark Koneff

United States Department of Agriculture Wildlife Services: Staff Publications

Legal removal of migratory birds from the wild occurs for several reasons, including subsistence, sport harvest, damage control, and the pet trade. We argue that harvest theory provides the basis for assessing the impact of authorized take, advance a simplified rendering of harvest theory known as potential biological removal as a useful starting point for assessing take, and demonstrate this approach with a case study of depredation control of black vultures (Coragyps atratus) in Virginia, USA. Based on data from the North American Breeding Bird Survey and other sources, we estimated that the black vulture population in Virginia …