Physical Sciences and Mathematics Commons^™

A Novel Technique To Improve Capture Success Of Common Ravens, Lindsey R. Perry, Terrah M. Owens, Zachary T. Slick, Jimmy Taylor, Jonathan B. Dinkins

United States Department of Agriculture Wildlife Services: Staff Publications

Traditional trapping techniques for common ravens (Corvus corax; raven) require significant effort, often produce low capture rates, and cannot be used in some situations. We designed a 3-m noose pole to secure ravens from nocturnal roost locations while using a strobe spotlight to temporarily disorient them. We collected measures of trapping efficiency and contrasted them with padded leghold traps also used in the study. We effectively implemented our noose pole method in July and August of 2018, 2019, and 2020 in the Baker and Cow Lakes sage-grouse (Centrocercus urophasianus) Priority Areas of Conservation in eastern Oregon, USA, which yielded trapping …

Evidence For Continental-Scale Dispersal Of Antimicrobial Resistant Bacteria By Landfill-Foraging Gulls, Christina A. Ahlstrom, Mariëlle L. Van Toor, Hanna Woksepp, Jeffrey C. Chandler, John A. Reed, Andrew B. Reeves, Jonas Waldenström, Alan B. Franklin, David C. Douglas, Jonas Bonnedahl, Andrew M. Ramey

United States Department of Agriculture Wildlife Services: Staff Publications

Anthropogenic inputs into the environment may serve as sources of antimicrobial resistant bacteria and alter the ecology and population dynamics of synanthropic wild animals by providing supplemental forage. In this study, we used a combination of phenotypic and genomic approaches to characterize antimicrobial resistant indicator bacteria, animal telemetry to describe host movement patterns, and a novel modeling approach to combine information fromthese diverse data streams to investigate the acquisition and long-distance dispersal of antimicrobial resistant bacteria by landfill-foraging gulls. Our results provide evidence that gulls acquire antimicrobial resistant bacteria from anthropogenic sources, which they may subsequently disperse across and between …

Evaluating Potential Effects Of Solar Power Facilities On Wildlife From An Animal Behavior Perspective, Rachel Y. Chock, Barbara Clucas, Elizabeth K. Peterson, Bradley Blackwell, Daniel T. Blumstein, Kathleen Church, Esteban Fernández-Juricic, Gabriel Francescoli, Alison L. Greggor, Paul Kemp, Gabriela M. Pinho, Peter M. Sanzenbacher, Bruce A. Schulte, Pauline Toni

United States Department of Agriculture Wildlife Services: Staff Publications

Solar power is a renewable energy source with great potential to help meet increasing global energy demands and reduce our reliance on fossil fuels. However, research is scarce on how solar facilities affect wildlife. With input from professionals in ecology, conservation, and energy, we conducted a research-prioritization process and identified key questions needed to better understand impacts of solar facilities on wildlife. We focused on animal behavior, which can be used to identify population responses before mortality or other fitness consequences are documented. Behavioral studies can also offer approaches to understand the mechanisms leading to negative interactions (e.g., collision, singeing, …

Principal Economic Effects Of Cormorant Predation On Catfish Farms, Carole R. Engle, Terrel W. Christie, Brian S. Dorr, Ganesh Kumar, Luke A. Roy, Anita M. Kelly

United States Department of Agriculture Wildlife Services: Staff Publications

Substantial economic losses of farmed catfish to fish-eating birds such as the double-crested cormorant, Phalacrocorax auritus, continue to be reported on U.S. catfish farms. An economic analysis was conducted of the on-farm effects of both the increased expenditures to scare fish-eating birds from catfish farms and of the value of the catfish that were consumed by cormorants. A survey was conducted of U.S. catfish farmers in the Delta region of Mississippi and Arkansas, to obtain farm-level data on expenditures to scare birds. Estimations of the lost revenue from catfish consumed by cormorants were developed from a concurrent study on …

Understanding Tolerance For An Invasive Species: An Investigation Of Hunter Acceptance Capacity For Wild Pigs (Sus Scrofa) In Texas, Hailey E. Mclean, Tara L. Teel, Alan Bright, Lauren M. Jaebker, John M. Tomecek, Maureen G. Frank, Rachael L. Connally, Stephanie A. Shwiff, Keith M. Carlisle

United States Department of Agriculture Wildlife Services: Staff Publications

Invasive species and their establishment in new areas have significant impacts on the ecological, economic, and social well-being of our planet. Wild pigs (Sus scrofa) are one of the world’s most formidable invasive species, particularly in the United States. They cause significant damage to agriculture and ecosystems, and can transmit diseases to livestock, wildlife, and people. There is an inherent social dimension to the issue of wild pigs due in part to the fact that people hunt them. Hunting contributes to both the control and spread of this species. The objectives of this study were to: 1) determine hunters’ overall …

Avian Influenza A Viruses Reassort And Diversify Differently In Mallards And Mammals, Ketaki Ganti, Anish Bagga, Juliana Dasilva, Samuel S. Shepard, John R. Barnes, Susan A. Shriner, Katia Koelle, Anice C. Lowen

United States Department of Agriculture Wildlife Services: Staff Publications

Reassortment among co-infecting influenza A viruses (IAVs) is an important source of viral diversity and can facilitate expansion into novel host species. Indeed, reassortment played a key role in the evolution of the last three pandemic IAVs. Observed patterns of reassortment within a coinfected host are likely to be shaped by several factors, including viral load, the extent of viral mixing within the host and the stringency of selection. These factors in turn are expected to vary among the diverse host species that IAV infects. To investigate host differences in IAV reassortment, here we examined reassortment of two distinct avian …

Evaluation Of A Warfarin Bait For Controlling Invasive Wild Pigs (Sus Scrofa), James C. Beasley, Lindsay M. Clontz, Allison Rakowski, Nathan P. Snow, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

BACKGROUND: Wild pigs (Sus scrofa) cause widespread environmental and economic damage, and as a result are subjected to extensive control. Current management strategies have proven insufficient, and there is growing interest in use of toxicants to control invasive populations of this species. In 2017 a low-dose warfarin bait was federally approved for use in controlling wild pigs in the United States. However, no states have allowed use of this bait due to unanswered questions regarding welfare concerns, field efficacy, and non-target impacts.

RESULTS: All captive wild pigs fed 0.005% warfarin baits in no choice feeding trials succumbed in an average …

Biodetection Of A Specific Odor Signature In Mallard Feces Associated With Infection By Low Pathogenic Avian Influenza A Virus, Glen J. Golden, Meredith Jj. Grady, Hailey E. Mclean, Susan A. Shriner, Airn E. Hartwig, Richard A. Bowen, Bruce A. Kimball

United States Department of Agriculture Wildlife Services: Staff Publications

Outbreaks of avian influenza virus (AIV) infection included the spread of highly pathogenic AIV in commercial poultry and backyard flocks in the spring of 2015. This resulted in estimated losses of more than $8.5 million from federal government expenditures, $1.6 billion from direct losses to produces arising from destroyed turkey and chicken egg production, and economy-wide indirect costs of $3.3 billion from impacts on retailers and the food service industries. Additionally, these outbreaks resulted in the death or depopulation of nearly 50 million domestic birds. Domesticated male ferrets (Mustela putorius furo) were trained to display a specific conditioned behavior (i.e. …

Relative Acceptance Of Brodifacoum Pellets And Soft Bait Sachets By Polynesian Rats (Rattus Exulans) On Wake Atoll, Peter J. Kappes, Shane R. Siers

United States Department of Agriculture Wildlife Services: Staff Publications

Removing invasive rats from island ecosystems using rodenticides has proven conservation benefits and is an important management tool for conserving and restoring island ecosystems. However, rodenticide-based eradications can fail if not all rats consume enough bait to result in lethal toxicosis. A recent post-operational review of a failed attempt to eradicate rats from Wake Atoll suggested that some individuals may not have ingested a lethal dose of rodenticide due to potential dietary and/or sensory preferences developed via regular access to anthropogenic food sources. These food sources may be higher in fats and oils, possessing different sensory properties (e.g., softer, chewier, …

Occurrence Of Mesocarnivores In Montane Sky Islands: How Spatial And Temporal Overlap Informs Rabies Management In A Regional Hotspot, Amanda M. Veals, John Koprowski, David L. Bergman, Kurt C. Vercauteren, David B. Wester

United States Department of Agriculture Wildlife Services: Staff Publications

Interspecific interactions among mesocarnivores can influence community dynamics and resource partitioning. Insights into these interactions can enhance understanding of local ecological processes that have impacts on pathogen transmission, such as the rabies lyssavirus. Host species ecology can provide an important baseline for disease management strategies especially in biologically diverse ecosystems and heterogeneous landscapes. We used a mesocarnivore guild native to the southwestern United States, a regional rabies hotspot, that are prone to rabies outbreaks as our study system. Gray foxes (Urocyon cinereoargenteus), striped skunks (Mephitis mephitis), bobcats (Lynx rufus), and coyotes (Canis latrans) share large portions of their geographic ranges …

Spatial Transferability Of Expert Opinion Models For American Beaver Habitat, Isidro Barela, Leslie M. Burger, Guiming Wang, Kristine O. Evans, Qingmin Meng, Jimmy D. Taylor

United States Department of Agriculture Wildlife Services: Staff Publications

Species distribution models and habitat suitability models (HSMs) have become a popular tool in the conservation of biodiversity. However, the ability to predict species spatial distributions at sites beyond the data source sites (i.e., spatial transferability) is critical for the applications of HSMs in the management and conservation of rare or endangered species. The main objective of our study was to assess the predictive performance and spatial transferability of expert opinion models (EOMs). To build EOMs, we identified through extensive literature reviews 17 key landscape variables to characterize habitat use by American beaver (Castor canadensis). We developed 31 pairwise opinion …

Food Habits Of Wintering Double-Crested Cormorants In The Mississippi Delta, Terrel W. Christie, Brian S. Dorr, J. Brian Davis, Luke A. Roy, Carole R. Engle, Katie Hanson-Dorr, Anita M. Kelly

United States Department of Agriculture Wildlife Services: Staff Publications

Given its ubiquity, it is not surprising that agriculture, including fin fish aquaculture, contributes to food webs worldwide and is used by numerous wildlife for foraging and meeting other needs. Double-crested Cormorants (Phalacrocorax auritus) impact United States commercial aquaculture and are considered the primary avian predator in catfish (Ictalurus spp.) aquaculture facilities in the Mississippi Delta. Recent changes in aquaculture practices, regulatory policies, and decreased overall hectares in production prompted this study that assessed cormorant consumption of catfish in relation to their night roosts through surveys and diet analysis. Cormorants were collected from night roosts from October …

Environmental Correlates Of Genetic Variation In The Invasive European Starling In North America, Natalie R. Hofmeister, Scott J. Werner, Irby J. Lovette

United States Department of Agriculture Wildlife Services: Staff Publications

Populations of invasive species that colonize and spread in novel environments may differentiate both through demographic processes and local selection. European starlings (Sturnus vulgaris) were introduced to New York in 1890 and subsequently spread throughout North America, becoming one of the most widespread and numerous bird species on the continent. Genome-wide comparisons across starling individuals and populations can identify demographic and/or selective factors that facilitated this rapid and successful expansion. We investigated patterns of genomic diversity and differentiation using reduced-representation genome sequencing of 17 winter-season sampling sites. Consistent with this species' high dispersal rate and rapid expansion history, …

Continental-Scale Dynamics Of Avian Influenza In U.S. Waterfowl Are Driven By Demography, Migration, And Temperature, Erin E. Gorsich, Colleen T. Webb, Andrew A. Merton, Jennifer A. Hoeting, Ryan S. Miller, Matthew Farnsworth, Seth R. Swafford, Thomas J. Deliberto, Kerri Pedersen, Alan B. Franklin, Robert G. Mclean, Kenneth R. Wilson, Paul Doherty

United States Department of Agriculture Wildlife Services: Staff Publications

Emerging diseases of wildlife origin are increasingly spilling over into humans and domestic animals. Surveillance and risk assessments for transmission between these populations are informed by a mechanistic understanding of the pathogens in wildlife reservoirs. For avian influenza viruses (AIV), much observational and experimental work in wildlife has been conducted at local scales, yet fully understanding their spread and distribution requires assessing the mechanisms acting at both local, (e.g., intrinsic epidemic dynamics), and continental scales, (e.g., long-distance migration). Here, we combined a large, continental-scale data set on low pathogenic, Type A AIV in the United States with a novel network-based …

Embracing Dynamic Models For Gene Drive Management, Andrew J. Golnar, Emily W. Ruell, Alun L. Lloyd, Kim M. Pepin

United States Department of Agriculture Wildlife Services: Staff Publications

Robust methods of predicting how gene drive systems will interact with ecosystems is essential for safe deployment of gene drive technology. We describe how quantitative tools can reduce risk uncertainty, streamline empirical research, guide risk management, and promote cross-sector collaboration throughout the process of gene drive technology development and implementation.

Gene drive technologies, although diverse in design and mode of action, are molecular architectures that promote the transmission of genetic information between generations. In theory, the release of one gene-drive-modified organism (GDMO) has the potential to irreversibly alter species, ecosystems, and environmental processes at a global scale (although in practice …

Population Genomic Transformations Induced By Isolation Of Wild Bird Avian Influenza Viruses (Orthomyxoviridae) In Embryonated Chicken Eggs, Matthew W. Hopken, Antoinette J. Piaggio, K. L. Pabilonia, James Pierce, Theodore Anderson, Courtney Pierce, Zaid Abdo

United States Department of Agriculture Wildlife Services: Staff Publications

Isolation and cultivation of wild-type viruses in model organism cells or tissues is standard practice in virology. Oftentimes, the virus host species is distantly related to the species from which the culture system was developed. Thus, virus culture in these tissues and cells basically constitutes a host jump, which can lead to genomic changes through genetic drift and/or adaptation to the culture system. We directly sequenced 70 avian influenza virus (Orthomyxoviridae) genomes from oropharyngeal/cloacal swabs collected from wild bird species and paired virus isolates propagated from the same samples following isolation in specific-pathogen-free embryonated chicken eggs. The data were analyzed …

Variation In Angiostrongylus Cantonensis Infection In Definitive And Intermediate Hosts In Hawaii, A Global Hotspot Of Rat Lungworm Disease, Chris Niebuhr, Shane R. Siers, Israel Leinbach, Lisa M. Kaluna, Susan I. Jarvi

United States Department of Agriculture Wildlife Services: Staff Publications

Angiostrongylus cantonensis (rat lungworm) is a tropical and subtropical parasitic nematode, with infections in humans causing angiostrongyliasis (rat lungworm disease), characterized by eosinophilic meningitis. Hawaii has been identified as a global hotspot of infection, with recent reports of high infection rates in humans, as well as rat definitive and snail intermediate hosts. This study investigated variation in A. cantonensis infection, both prevalence and intensity, in wild populations of two species of rats (Rattus exulans and R. rattus) and one species of snail (Parmarion martensi). An overall infection prevalence of 86.2% was observed in P. martensi and …

Estimation Of Wildlife Damage From Federal Crop Insurance Data, Sophie Mckee, Stephanie A. Shwiff, Aaron M. Anderson

United States Department of Agriculture Wildlife Services: Staff Publications

BACKGROUND: Wildlife damage to crops is a persistent and costly problem for many farmers in the USA. Most existing estimates of crop damage have relied on direct assessment methods such as field studies conducted by trained biologists or surveys distributed to farmers. In this paper, we describe a new method of estimating wildlife damage that exploits federal crop insurance data. We focused our study on four crops: corn, soybean, wheat, and cotton, chosen because of their economic importance and their vulnerability to wildlife damage.

RESULTS: We determined crop-raiding hot spots across the USA over the 2015–2019 period and identified the …

Inefficiency Of Anthraquinone-Based Avian Repellents When Applied To Sunflower: The Importance Of Crop Vegetative And Floral Characteristics In Field Applications, Brandon Kaiser, Burton L. Johnson, Mike Ostlie, Scott J. Werner, Page E. Klug

United States Department of Agriculture Wildlife Services: Staff Publications

BACKGROUND: Blackbirds (Icteridae) cause significant damage to sunflower (Helianthus annuus L.) prompting the need for effective management tools. Anthraquinone-based repellents can reduce feeding by > 80% in laboratory settings, but require birds to learn the negative association through repellent ingestion. We evaluated an anthraquinone-based repellent applied directly to mature sunflower plants for its ability to reduce bird damage. We used captive male red-winged blackbirds (Agelaius phoeniceus) to evaluate efficacy of two anthraquinone-based formulations in varying concentrations and applied in a manner attainable by sunflower producers. We also assessed field application methods for repellent coverage and anthraquinone residues when …

Avian Use Of Exotic Street Treescapes In Metropolitan Areas Of Phoenix, Arizona, Brian E. Washburn, Karen Hoss, David L. Bergman

United States Department of Agriculture Wildlife Services: Staff Publications

Urban areas are highly modified environments that are strongly influenced by a variety of anthropogenic factors. Consequently, these areas contain unique wildlife communities typically dominated by species that are generalist in nature or highly adaptable. We examined the use of five species of exotic treescapes by exotic and native birds in metropolitan areas of Phoenix, Arizona. House Sparrows [Passer domesticus (37%)], European Starlings [Sturnus vulagris (27%)], Mourning Doves [Zenaida macroura (11%)], and Great-tailed Grackles [Quiscalus mexicanus (7%)] were the most frequently observed species during the study. Approximately two-thirds (67%) of the birds observed during the study were exotic species. Avian …

Anthraquinone Repellent Seed Treatment On Corn Reduces Feeding By Wild Pigs, Nathan P. Snow, Joseph M. Halseth, Scott J. Werner, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Wild pigs (Sus scrofa) are a destructive invasive species that cause extensive damage to agriculture throughout many regions of the world. In particular wild pigs damage corn more than any other crop, and most of that damage occurs immediately after planting when wild pigs excavate and consume planted seeds. We evaluated whether anthraquinone (AQ), a repellent, could be useful for protecting seed corn from consumption by wild pigs. Specifically, we conducted cafeteria-style tests at 16 bait sites for 6 nights using concentrations of: untreated, 0.5, 1.5, and 3.0% AQ by weight sprayed on whole-kernel corn in AL and …

The Evolutionary Consequences Of Human–Wildlife Conflict In Cities, Christopher J. Schell, Lauren Stanton, Julie K. Young, Lisa Angeloni, Joanna E. Lambert, Stewart W. Breck, Maureen H. Murray

United States Department of Agriculture Wildlife Services: Staff Publications

Human–wildlife interactions, including human–wildlife conflict, are increasingly common as expanding urbanization worldwide creates more opportunities for people to encounter wildlife. Wildlife–vehicle collisions, zoonotic disease transmission, property damage, and physical attacks to people or their pets have negative consequences for both people and wildlife, underscoring the need for comprehensive strategies that mitigate and prevent conflict altogether. Management techniques often aim to deter, relocate, or remove individual organisms, all of which may present a significant selective force in both urban and nonurban systems. Managementinduced selection may significantly affect the adaptive or nonadaptive evolutionary processes of urban populations, yet few studies explicate the …

Modeling Mongoose Rabies In The Caribbean: A Model-Guided Fieldwork Approach To Identify Research Priorities, Caroline C. Sauvé, Erin E. Rees, Amy T. Gilbert, Are R. Berentsen, Agathe Allibert, Patrick A. Leighton

United States Department of Agriculture Wildlife Services: Staff Publications

We applied the model-guided fieldwork framework to the Caribbean mongoose rabies system by parametrizing a spatially-explicit, individual-based model, and by performing an uncertainty analysis designed to identify parameters for which additional empirical data are most needed. Our analysis revealed important variation in output variables characterizing rabies dynamics, namely rabies persistence, exposure level, spatiotemporal distribution, and prevalence. Among epidemiological parameters, rabies transmission rate was the most influential, followed by rabies mortality and location, and size of the initial infection. The most influential landscape parameters included habitat-specific carrying capacities, landscape heterogeneity, and the level of resistance to dispersal associated with topography. Movement …

A Framework For Surveillance Of Emerging Pathogens At The Human-Animal Interface: Pigs And Coronaviruses As A Case Study, Kim M. Pepin, Ryan S. Miller, Mark Q. Wilber

United States Department of Agriculture Wildlife Services: Staff Publications

Pigs (Sus scrofa) may be important surveillance targets for risk assessment and risk-based control planning against emerging zoonoses. Pigs have high contact rates with humans and other animals, transmit similar pathogens as humans including CoVs, and serve as reservoirs and intermediate hosts for notable human pandemics. Wild and domestic pigs both interface with humans and each other but have unique ecologies that demand different surveillance strategies. Three fundamental questions shape any surveillance program: where, when, and how can surveillance be conducted to optimize the surveillance objective? Using theory of mechanisms of zoonotic spillover and data on risk factors, …

Factors Influencing Survival Rates Of Pronghorn Fawns In Idaho, Brett R. Panting, Eric M. Gese, Mary M. Conner, Scott Bergen

United States Department of Agriculture Wildlife Services: Staff Publications

Pronghorn (Antilocapra americana) occur throughout western North America. In Idaho, USA, following intensive hunting to reduce crop depredations in the late 1980s, pronghorn populations have not rebounded to desired levels. Because neonatal survival in ungulates is one factor limiting population growth, we evaluated cause‐specific mortality and the influence of intrinsic and extrinsic factors on survival rates of 217 radio‐collared pronghorn fawns across 3 study areas in Idaho during 2015–2016. For intrinsic variables, we determined the sex and body mass index (BMI) for each fawn. For extrinsic variables, we determined the abundance of predators and alternate prey, estimated the …

Avian Influenza A Viruses Reassort And Diversify Differently In Mallards And Mammals, Ketaki Ganti, Anish Bagga, Juliana Dasilva, Samuel S. Shepard, John R. Barnes, Susan A. Shriner, Katia Koelle, Anice C. Lowen

United States Department of Agriculture Wildlife Services: Staff Publications

Reassortment among co-infecting influenza A viruses (IAVs) is an important source of viral diversity and can facilitate expansion into novel host species. Indeed, reassortment played a key role in the evolution of the last three pandemic IAVs. Observed patterns of reassortment within a coinfected host are likely to be shaped by several factors, including viral load, the extent of viral mixing within the host and the stringency of selection. These factors in turn are expected to vary among the diverse host species that IAV infects. To investigate host differences in IAV reassortment, here we examined reassortment of two distinct avian …

Behavioral State Resource Selection In Invasive Wild Pigs In The Southeastern United States, Lindsay M. Clontz, Kim M. Pepin, Kurt C. Vercauteren, James C. Beasley

United States Department of Agriculture Wildlife Services: Staff Publications

Elucidating correlations between wild pig (Sus scrofa) behavior and landscape attributes can aid in the advancement of management strategies for controlling populations. Using GPS data from 49 wild pigs in the southeastern U.S., we used hidden Markov models to define movement path characteristics and assign behaviors (e.g., resting, foraging, travelling). We then explored the connection between these behaviors and resource selection for both sexes between two distinct seasons based on forage availability (i.e., low forage, high forage). Females demonstrated a crepuscular activity pattern in the high-forage season and a variable pattern in the low-forage season, while males exhibited nocturnal activity …

Impacts Of A Large Invasive Mammal On Water Quality In Riparian Ecosystems, Sara Bolds, B. Graeme Lockaby, Stephen S. Ditchkoff, Mark D. Smith, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Wild pigs (Sus scrofa) are a highly invasive species in many regions of the world and can act as ecosystem engineers in areas where they are established. In riparian ecosystems, wild pigs may affect water quality parameters and introduce fecal bacteria, although previous studies have reported conflicting results. We propose four conditions that we believe are needed for an accurate assessment of wild pig impacts on water quality and address each one in our study. Water samples were collected between May 2018 and June 2019 in riparian watersheds on a privately owned property in Alabama that was densely populated by …

Modelling The Factors Affecting The Probability For Local Rabies Elimination By Strategic Control, Johann L. Kotzé, John Duncan Grewar, Aaron M. Anderson

United States Department of Agriculture Wildlife Services: Staff Publications

Dog rabies has been recognized from ancient times and remains widespread across the developing world with an estimated 59,000 people dying annually from the disease. In 2011 a tri-partite alliance consisting of the OIE, the WHO and the FAO committed to globally eliminating dog-mediated human rabies by 2030. Regardless of global support, the responsibility remains with local program managers to implement successful elimination programs. It is well known that vaccination programs have a high probability of successful elimination if they achieve a population-coverage of 70%. It is often quoted that reducing population turnover (typically through sterilizations) raises the probability for …

Diets Of Double-Crested Cormorants In The Lake Winnebago System, Wisconsin, Ryan P. Koenigs, Daniel J. Dembkowski, Charles D. Lovell, Daniel A. Isermann, Adam D. Nickel

United States Department of Agriculture Wildlife Services: Staff Publications

Double-crested cormorant Phalacrocorox auritus Lesson (cormorant) populations have increased throughout the Great Lakes region of North America causing concern related to the impact of cormorant predation on fish communities. A recent decline in yellow perch Perca flavescens (Mitchill) abundance within the Lake Winnebago System, Wisconsin, USA, prompted an assessment of cormorant diets to evaluate potential effects of cormorant predation on the sportfish community. Diets were collected from 883 cormorants (417 from Lake Winnebago and 466 from Lake Butte des Morts) between 2015 and 2017. Cormorant diets on both waterbodies consisted mostly of freshwater drum Aplodinotus grunniens Rafinesque and gizzard shad …