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USGS2023

Influence of fine-scale habitat characteristics on sage-grouse nest site selection and nest survival varies by mesic and xeric site conditions

Resource managers and scientists across western U.S. agencies seek methodologies for identifying environmental attributes important to both wildlife conservation and broad-scale land stewardship. The Greater Sage-Grouse ( Centrocercus urophasianus ; hereafter, sage-grouse) exemplifies a species in need of this broad-scale approach given widespread population declines that have resulted from loss and degradation of habitat from natural and anthropogenic disturbances. These include agricultural land conversion, conifer expansion, energy development, and wildfire coupled with ecological conversion by invasive plants such as cheatgrass ( Bromus tectorum ). Development of habitat assessments and conservation actions for sage-grouse benefit from studies that link demographic responses to habitat selection patterns. To address this, we examined nest survival of sage-grouse in relation to fine-scale habitat patterns (i.e., field-based habitat measurements) that influenced nest site selection, using data from nests of telemetered females at 17 sites over 6 years in Nevada and northeastern California, USA. Importantly, sites spanned mesic and xeric average precipitation conditions that contributed substantially to vegetation community structure across cold desert ecosystems of the North American Great Basin. Vegetative cover immediately surrounding sage-grouse nests was important for both nest site selection and nest survival, but responses varied between mesic and xeric sites. For example, while taller perennial grasses were selected at xeric sites, we found no evidence of selection for perennial grass at mesic sites, indicating a functional response to availability of habitat features between hydrographic regions. Furthermore, perennial grass height and forb height both had positive effects on nest survival at xeric sites, but we found varying effects at mesic sites. We emphasize that precipitation conditions driving ecosystem productivity vary regionally among sagebrush communities, shaping vegetation structure and suitable habitat conditions for nesting sage-grouse.

Ornithological Applications↗

USGS2017

Differences in breeding bird assemblages related to reed canary grass cover cover and forest structure on the Upper Mississippi River

Floodplain forest of the Upper Mississippi River provides habitat for an abundant and diverse breeding bird community. However, reed canary grass Phalaris arundinacea invasion is a serious threat to the future condition of this forest. Reed canary grass is a well-known aggressive invader of wetland systems in the northern tier states of the conterminous United States. Aided by altered flow regimes and nutrient inputs from agriculture, reed canary grass has formed dense stands in canopy gaps and forest edges, retarding tree regeneration. We sampled vegetation and breeding birds in Upper Mississippi River floodplain forest edge and interior areas to 1) measure reed canary grass cover and 2) evaluate whether the breeding bird assemblage responded to differences in reed canary grass cover. Reed canary grass was found far into forest interiors, and its cover was similar between interior and edge sites. Bird assemblages differed between areas with more or less reed canary grass cover (.53% cover breakpoint). Common yellowthroat Geothlypis trichas , black-capped chickadee Parus atricapillus , and rose-breasted grosbeak Pheucticus ludovicianus were more common and American redstart Setophaga ruticilla , great crested flycatcher Myiarchus crinitus , and Baltimore oriole Icterus galbula were less common in sites with more reed canary grass cover. Bird diversity and abundance were similar between sites with different reed canary grass cover. A stronger divergence in bird assemblages was associated with ground cover ,15%, resulting from prolonged spring flooding. These sites hosted more prothonotary warbler Protonotaria citrea , but they had reduced bird abundance and diversity compared to other sites. Our results indicate that frequently flooded sites may be important for prothonotary warblers and that bird assemblages shift in response to reed canary grass invasion.

Upper Mississippi River↗

USGS2011

Seroprevalence of West Nile Virus in feral horses on Sheldon National Wildlife Refuge, Nevada, United States

We screened 1,397 feral horses ( Equus caballus ) on Sheldon National Wildlife Refuge, Nevada, United States, for IgM and IgG against flavivirus during 2004–2006, 2008, and 2009. Positive serum samples were tested for neutralizing antibodies to West Nile virus (WNV) and St. Louis encephalitis virus (SLEV). One animal was positive for antibody against WNV in 2004, but all others tested in 2004–2006 were negative. In 2008 and 2009, we found evidence of increasing seropositive horses with age, whereas seroprevalence of WNV decreased from 19% in 2008 to 7.2% in 2009. No horses were positive for antibody against SLEV. Being unvaccinated, feral horses can be useful for WNV surveillance.

Nevada↗

USGS2020

Biological assessment of a proposed vegetation management program to benefit tribes in eastern Oklahoma

Tribal communities may benefit from land management activities that enhance their use of resources on tribal lands. The Bureau of Indian Affairs is implementing a 5-year vegetation management program to provide support for projects that develop and use natural and cultural resources and improve opportunities for agricultural activities to benefit 20 Indian Tribes and Nations in the Eastern Oklahoma Region of the Bureau of Indian Affairs. The bureau is working with individual Tribes to identify project objectives and design treatments, which include prescribed burning, timber removal, thinning, and reduction of hazardous fuels. The total action area for the vegetation management program is estimated to be 236,575 acres, representing approximately 1 percent of the region. A biological assessment was prepared, in cooperation with the bureau and U.S. Fish and Wildlife Service, to evaluate the potential effects of the proposed vegetation management program on 22 federally threatened, endangered, and candidate species that may occur within the Eastern Oklahoma Region. The species evaluated included one plant, two insects, one reptile, five fresh-water mussels, four fishes, five birds, and four bats. Because the proposed treatments will be largely restricted to terrestrial systems, it is expected that there will be no adverse effects on the 15 species associated with aquatic habitats, provided that best management practices are followed. The proposed treatments may affect but are unlikely to adversely affect six of the primarily terrestrial species (the Papaipema eryngii [rattlesnake master borer], Picoides borealis [red-cockaded woodpecker], Myotis grisescens [gray bat], Myotis sodalis [Indiana bat], Myotis septentrionalis [northern long-eared bat], and Corynorhinus townsendii ingens [Ozark big-eared bat]), provided that best management practices are followed, including avoidance of critical habitat features. The only species likely to be adversely affected by the proposed treatments is Nicrophorus americanus (American burying beetle) as a consequence of short-term disturbances to soils and vegetation. Most adverse effects of the treatments (such as soil compaction and decreased cover in the forest understory) are expected to be short term (habitat will recover or be restored within 5 years of treatments). Less than 1 percent of the action area is expected to result in long-term adverse effects to the American burying beetle as a result of permanent cover changes that persist for more than 5 years. It is expected that the primary treatments will be largely beneficial to the American burying beetle population in the region by reducing the risk of high-severity fires and expansion of invasive woody shrubs, such as Juniperus virginiana (eastern redcedar) within potential beetle habitat and the surrounding landscape. Overall, the proposed management program is expected to provide long-term benefits to American burying beetle habitat across 91 percent of the action area.

Oklahoma↗

USGS1991

Population trends from the American woodcock singing-ground survey, 1970-88

Population trend analysis of American woodcook ( Scolopax minor ) using data from a singing-ground survey indicates population declines throughout the breeding range of the species between 1970 and 1988. In the eastern United States and Canada, this decline has been quite consistent throughout the period, but in the central portion of the continent the population increased during the 1970's and declined during the early 1980's. Observers differ in their ability to hear woodcock, and we document observer differences in the singing-ground survey data and incorporate them into our analyses. Habitat changes have been suggested as the most likely cause of declines in woodcock populations.

Journal of Wildlife Management↗

USGS2013

Estimating raptor nesting success: old and new approaches

Studies of nesting success can be valuable in assessing the status of raptor populations, but differing monitoring protocols can present unique challenges when comparing populations of different species across time or geographic areas. We used large datasets from long-term studies of 3 raptor species to compare estimates of apparent nest success (ANS, the ratio of successful to total number of nesting attempts), Mayfield nesting success, and the logistic-exposure model of nest survival. Golden eagles (Aquila chrysaetos), prairie falcons (Falco mexicanus), and American kestrels (F. sparverius) differ in their breeding biology and the methods often used to monitor their reproduction. Mayfield and logistic-exposure models generated similar estimates of nesting success with similar levels of precision. Apparent nest success overestimated nesting success and was particularly sensitive to inclusion of nesting attempts discovered late in the nesting season. Thus, the ANS estimator is inappropriate when exact point estimates are required, especially when most raptor pairs cannot be located before or soon after laying eggs. However, ANS may be sufficient to assess long-term trends of species in which nesting attempts are highly detectable.

Journal of Wildlife Management↗

USGS1984

Disseminated visceral coccidiosis in sandhill cranes

Disseminated visceral coccidiosis (DVC) caused by Eimeria spp was first recognized as a disease entity in captive sandhill cranes (Grus canadensis) and whooping cranes (G americana) at the Patuxent Wildlife Research Center. Because cranes produced at the Center are reintroduced to the wild to augment wild populations, studies involving both experimentally induced and natural infections were initiated to determine the potential or actual occurrence of DVC in wild Gruidae. Nine sandhill cranes dosed orally with eimerian oocysts of wild origin developed lesions characteristic of DVC. Extraintestinal granulomas associated with developing schizonts were found in 6 birds. Similar lesions were observed in wild sandhill cranes throughout parts of midwestern United States, Alaska, and Saskatchewan. These studies revealed the wide geographic distribution and the high frequency of occurrence of DVC in wild cranes.

Journal of the American Veterinary Medical Associa↗

USGS2007

Evolving plans for the USA National Phenology Network

Phenology is the study of periodic plant and animal life cycle events, how these are influenced by seasonal and interannual variations in climate, and how they modulate the abundance, diversity, and interactions of organisms. The USA National Phenology Network (USA-NPN) is currently being organized to engage federal agencies, environmental networks and field stations, educational institutions, and citizen scientists. The first USA-NPN planning workshop was held August 2005, in Tucson, Ariz. (Betancourt et al. [2005]; http://www.uwm.edu/Dept/Geography/npn/; by 1 June 2007, also see http://www.usanpn.org). With sponsorship from the U.S. National Science Foundation, the U.S. Geological Survey (USGS), the U.S. Fish and Wildlife Service, and NASA, the second USA-NPN planning workshop was held at the University of Wisconsin-Milwaukee on 10–12 October 2006 to (1) develop lists of target species and observation protocols; (2) identify existing networks that could comprise the backbone of nationwide observations by 2008; (3) develop opportunities for education, citizen science, and outreach beginning in spring 2007; (4) design strategies for implementing the remote sensing component of USA-NPN; and (5) draft a data management and cyberinfrastructure plan.

Eos, Transactions, American Geophysical Union↗

USGS2020

Strategic Plan for the North American Breeding Bird Survey, 2020–30

The North American Breeding Bird Survey (BBS) has been the cornerstone of continental bird conservation and management for hundreds of North American bird species in the United States and Canada for more than 50 years. This strategic plan was developed in collaboration with key partners and stakeholders and charts the ambitious course for the BBS over the next decade (2020–30). Using this plan as a guide, the BBS program will set out to improve the breadth and depth of standardized data collection and analytical products; ensure its products are widely used and recognized as the authoritative source for long-term population change information for most birds; and secure adequate resources, internally and through partnerships, to realize the expanded vision of the BBS intended to support avian management needs through 2030.

Circular↗

USGS2013

Newly documented host fishes for the eastern elliptio mussel (Elliptio complanata)

The eastern elliptio Elliptio complanata is a common, abundant, and ecologically important freshwater mussel that occurs throughout the Atlantic Slope drainage in the United States and Canada. Previous research has shown E. complanata glochidia to be host fish generalists, parasitizing yellow perch Perca flavescens , banded killifish Fundulus diaphanus , banded sculpin Cottus carolinae , and seven centrarchid species. Past laboratory studies have been conducted in the Midwest; however, glochidia used in these studies were obtained from adult mussels in the Great Lakes or St. Lawrence River basins, or glochidia sources were not reported. The objective of this study was to identify host fishes for E. complanata from streams in the Mid-Atlantic region. We used artificial laboratory infections to test host suitability of 38 fish and 2 amphibian species with E. complanata glochidia from the Chesapeake Bay drainage. Glochidia successfully metamorphosed into juvenile mussels on five fish species: American eel Anguilla rostrata , brook trout Salvelinus fontinalis , lake trout Salvelinus namaycush , mottled sculpin Cottus bairdii , and slimy sculpin Cottus cognatus . American eel was the most effective host, yielding the highest overall metamorphosis success (percentage of attached glochidia that transformed into juvenile mussels; ≥0.90) and producing 13.2 juveniles per fish overall. No juvenile E. complanata metamorphosed on other fish or amphibian species tested, including many previously identified host fishes that appear in the literature. Reasons for discrepancies in published host fish could include geographic variation in host use across the species' range, differences in host use between lentic and lotic populations, or poorly resolved taxonomy within the genus Elliptio .

Journal of Fish and Wildlife Management↗

USGS2006

Conceptual ecological model for management of breeding shrubland birds in the Mid-Atlantic Region

While grassland birds have become the focus of increased conservation activities, the status of birds occupying shrubland habitats has received relatively little attention (Hunter et al. 2001). Yet, in eastern North America, shrubland birds exhibited consistent population declines during the past 40 years, based on data from the North American Breeding Bird Survey (Pardieck and Sauer 2001). These population declines primarily reflect large-scale changes in land use patterns during the previous century (Lorimer 2001). Large areas of marginal farmland were abandoned and underwent secondary succession during the first half of the twentieth century, producing abundant successional habitats favored by shrubland birds. As these habitats matured, combined with strict fire-suppression policies (Hunter et al. 2001), shrublands succeeded into mature forests, and shrubland bird communities were replaced by woodland birds (Irland 1982; Askins 1993). For example, while nearly 29% of New England forests were classified as sapling stage in 1950, only 8% remained at that stage in the 1980s (Askins 1993). The trend towards forest maturation and loss of shrubland habitats continues, yet concerted conservation activities have not been directed to benefit declining shrubland bird populations. The National Park Service (NPS) could contribute to shrubland bird conservation in the Mid- Atlantic Region. The NPS maintains a number of historic sites and former battlefields managed for their cultural significance but also support wildlife populations. Many of these “cultural parks” maintain open landscapes, recreating land use patterns existing at the times of the historical events. While these open landscapes are frequently managed grasslands, some parks also support successional habitats that could be managed to benefit shrubland birds. In 2005, the NPS initiated a project exploring the potential of “cultural parks” to support significant breeding grassland and shrubland bird communities. This project involved parks within three NPS Inventory and Monitoring Program (I&M) networks, Mid-Atlantic, National Capital, and Eastern Rivers and Mountains. Five parks were selected for the initial focus of this study, all of which maintain open landscapes for interpreting historic events. Most parks were selected because they contain the most extensive grassland habitats within their networks, although some also support shrubby successional habitats. The five parks included in this study are Antietam National Battlefield, Fort Necessity National Battlefield, Gettysburg National Battlefield, Manassas National Battlefield, and Monocacy National Battlefield. This conceptual ecological model is one product of this project. The information presented below allows NPS network coordinators to understand which factors should be considered when making decisions concerning shrubland management within their networks. This model provides park resource managers with information on shrubland ecology in the Mid-Atlantic Region, the ecological requirements of shrubland birds likely to occur in their parks, and management issues influencing whether significant breeding populations can occupy shrublands created and maintained in the parks. Resource managers can then make informed decisions concerning their ability to create and maintain shrubland habitats. The emphasis of this conceptual model is restricted to management of breeding shrubland birds. Additional species occur during migration and winter, and habitat requirements of shrubland birds during nonbreeding seasons may differ from those described for the breeding season.

Technical Report↗

USGS2009

Genetic conservation and paddlefish propagation

The conservation of genetic diversity of our natural resources is overwhelmingly one of the central foci of 21st century management practices. Three recommendations related to the conservation of paddlefish Polyodon spathula genetic diversity are to (1) identify genetic diversity at both nuclear and mitochondrial DNA loci using a suggested list of 20 sampling locations, (2) use genetic diversity estimates to develop genetic management units, and (3) identify broodstock sources to minimize effects of supplemental stocking on the genetic integrity of native paddlefish populations. We review previous genetic work on paddlefish and described key principles and concepts associated with maintaining genetic diversity within and among paddlefish populations and also present a genetic case study of current paddlefish propagation at the U.S. Fish and Wildlife Service Gavins Point National Fish Hatchery. This study confirmed that three potential sources of broodfish were genetically indistinguishable at the loci examined, allowing the management agencies cooperating on this program flexibility in sampling gametes. This study also showed significant bias in the hatchery occurred in terms of male reproductive contribution, which resulted in a shift in the genetic diversity of progeny compared to the broodfish. This shift was shown to result from differential male contributions, partially attributed to the mode of egg fertilization. Genetic insights enable implementation of a paddlefish propagation program within an adaptive management strategy that conserves inherent genetic diversity while achieving demographic goals.

American Fisheries Society Symposium↗

USGS2013

Predicting breeding shorebird distributions on the Arctic Coastal Plain of Alaska

The Arctic Coastal Plain (ACP) of Alaska is an important region for millions of migrating and nesting shorebirds. However, this region is threatened by climate change and increased human development (e.g., oil and gas production) that have the potential to greatly impact shorebird populations and breeding habitat in the near future. Because historic data on shorebird distributions in the ACP are very coarse and incomplete, we sought to develop detailed, contemporary distribution maps so that the potential impacts of climate-mediated changes and development could be ascertained. To do this, we developed and mapped habitat suitability indices for eight species of shorebirds (Black-bellied Plover [Pluvialis squatarola], American Golden-Plover [Pluvialis dominica], Semipalmated Sandpiper [Calidris pusilla], Pectoral Sandpiper [Calidris melanotos], Dunlin [Calidris alpina], Long-billed Dowitcher [Limnodromus scolopaceus], Red-necked Phalarope [Phalaropus lobatus], and Red Phalarope [Phalaropus fulicarius]) that commonly breed within the ACP of Alaska. These habitat suitability models were based on 767 plots surveyed during nine years between 1998 and 2008 (surveys were not conducted in 2003 and 2005), using single-visit rapid area searches during territory establishment and incubation (8 June, 1 July). Species specific habitat suitability indices were developed and mapped using presence-only modeling techniques (partitioned Mahalanobis distance) and landscape environmental variables. For most species, habitat suitability was greater at lower elevations (i.e., near the coast and river deltas) and lower within upland habitats. Accuracy of models was high for all species, ranging from 65 -98%. Our models predicted that the largest fraction of suitable habitat for the majority of species occurred within the National Petroleum Reserve-Alaska, with highly suitable habitat also occurring within coastal areas of the Arctic National Wildlife Refuge west to Prudhoe Bay.

Alaska↗

USGS2021

U.S. Geological Survey landscape science strategy 2020–2030

Across our Nation, multiple Federal, State, Tribal, and local governments are working with stakeholders and landowners to restore, conserve, and manage lands and resources to benefit fish, wildlife, and people. One of the largest Federal efforts is led by the U.S. Department of the Interior (DOI), with multiple DOI agencies working to conserve and manage public lands, resources, and cultural heritage for the benefit and enjoyment of current and future generations. As a science provider within the DOI, the U.S. Geological Survey (USGS) has an important role in developing actionable science products that can inform decision making on public lands and across all of our Nation’s landscapes. Our landscapes and resources are undergoing continual change from a complex and interacting suite of stressors that include traditional and nontraditional land uses, a changing climate, a dynamic economy, and a culturally diverse and ever-changing society. Landscape science seeks to understand how the physical, biological, and social components of ecosystems and landscapes interact with each other and are affected by these stressors across local to global scales. The USGS has developed this landscape science strategy to focus and strengthen the agency’s efforts to inform critical conservation, restoration, and management decisions for American landscapes. The strategy directly supports the overarching 21st-century science strategy of the USGS and expands our perspective and focus on partnerships, including with internal, external, traditional, and nontraditional partners. The vision for USGS landscape science is to integrate multiple disciplines and approaches to create and deliver relevant, timely, and scientifically sound products that enable our partners to make informed decisions about how to manage complex interacting natural and human systems across changing American landscapes. This strategy seeks to leverage the expertise, data, analytical capacity, and tools of the agency and to strengthen integration of science efforts across programs and scales. A cornerstone of the strategy is working closely with landowners and resource managers to identify the science that is needed to inform management actions, and then working collaboratively with those same partners to coproduce science and data products that are timely, practical, and useful for their decision making. Many individual efforts within the USGS already embrace landscape science ideas and practices. With the development of this strategy, we are seeking to build on these efforts and to focus agency attention and expertise on expanding, connecting, and institutionalizing core practices and approaches for landscape science that produces actionable science products and tools that decision makers can use to help conserve and manage American landscapes.

Circular↗

USGS1984

Tissue lead distribution and hematologic effects in American kestrels (Falco sparverius) fed biologically incorporated lead

American kestrels were fed a diet containing 0.5, 120, 212, and 448 ppm (dry wt) biologically incorporated lead (Pb) for 60 days. The diet consisted of homogenized 4-wk-old cockerels raised on feed mixed with and without lead. No kestrels died and weights did not differ among treatment groups. The control group (0.5 ppm Pb) had the lowest mean concentration of lead and the high dietary group had the highest for the following tissues: Kidney, liver, femur, brain, and blood. Concentrations of lead were significantly correlated among tissues. There were no differences among treatment groups for packed cell volume, hemoglobin concentration, or erythrocyte count.

Journal of Wildlife Diseases↗

USGS2020

Drivers and consequences of alternative landscape futures on wildlife distributions in New England, United States

In an era of rapid climate and land transformation, it is increasingly important to understand how future changes impact natural systems. Scenario studies can offer the structure and perspective needed to understand the impacts of change and help inform management and conservation decisions. We implemented a scenario-based approach to assess how two high impact drivers of landscape change influence the distributions of managed wildlife species (n = 10) in the New England region of the northeastern United States. We used expert derived species distribution models (SDMs) and scenarios developed by the New England Landscape Futures Project (NELFP) to estimate how species distributions change under various trajectories (n = 5) of landscape change. The NELFP scenarios were built around two primary drivers – Socio-Economic Connectedness (SEC) and Natural Resource Planning and Innovation (NRPI) – and provide plausible alternatives for how the New England region may change over fifty years (2010 to 2060). Our models generally resulted in species occurrence and richness declines by 2060. The majority of species (7 of 10) experienced declines in regional occurrence for all NELFP scenarios, and one species experienced a projected increase in mean regional occurrence for all scenarios. Our results indicate that the NRPI and SEC drivers strongly influenced projected distribution changes compared to baseline projections. NRPI had a greater impact on distribution change for five species (coyote, moose, striped skunk, white-tailed deer, and wild turkey), while SEC had a greater impact on four species (American black bear, bobcat, raccoon, and red fox); one species (gray fox) was equally influenced by both NRPI and SEC. These results emphasize the importance of integrating both natural resource planning and socio-economic factors when addressing issues of distribution change and offer insights that can inform proactive management and conservation planning.

Connecticut, Maine, Massachusetts, New Hampshire, ↗

USGS2021

Poecivirus is present in individuals with beak deformities in seven species of North American birds

Avian keratin disorder (AKD), a disease of unknown etiology characterized by debilitating beak overgrowth, has increasingly affected wild bird populations since the 1990s. A novel picornavirus, poecivirus, is closely correlated with disease status in Black-capped Chickadees ( Poecile atricapillus ) in Alaska. However, our knowledge of the relationship between poecivirus and beak deformities in other species and other geographic areas remains limited. The growing geographic scope and number of species affected by AKD-like beak deformities require a better understanding of the causative agent to evaluate the population-level impacts of this epizootic. Here, we tested eight individuals from six avian species with AKD-consistent deformities for the presence of poecivirus: Mew Gull ( Larus canus ), Hairy Woodpecker ( Picoides villosus ), Black-billed Magpie ( Pica hudsonia ), American Crow ( Corvus brachyrhynchos ), Red-breasted Nuthatch ( Sitta canadensis ), and Blackpoll Warbler ( Setophaga striata ). The birds were sampled in Alaska and Maine (1999−2016). We used targeted PCR followed by Sanger sequencing to test for the presence of poecivirus in each specimen and to obtain viral genome sequence from virus-positive host individuals. We detected poecivirus in all individuals tested, but not in negative controls (water and tissue samples). Furthermore, we used unbiased metagenomic sequencing to test for the presence of other pathogens in six of these specimens (Hairy Woodpecker, two American Crows, two Red-breasted Nuthatches, Blackpoll Warbler). This analysis yielded additional viral sequences from several specimens, including the complete coding region of poecivirus from one Red-breasted Nuthatch, which we confirmed via targeted PCR followed by Sanger sequencing. This study demonstrates that poecivirus is present in individuals with AKD-consistent deformities from six avian species other than Black-capped Chickadee. While further investigation will be required to explore whether there exists a causal link between this virus and AKD, this study demonstrates that poecivirus is not geographically restricted to Alaska, but rather occurs elsewhere in North America.

Alaska, Maine↗

USGS1979

Diet-related die-off of captive black-crowned night herons

Several species of herons, which are top-level consumers in aquatic food chains, have experienced population declines in certain areas o f their normal range (7,13) -- areas in which elevated levels of various environmental pollutants are known to occur. (6) To determine the effects of environmental contaminants on the Ardeidae, a colony of black-crowned night herons (Nycticorax nycticorax) was established in 1972 at the Patuxent Wildlife Research Center. The night heron was selected as the model species because of its widespread occurrence and its ability to survive and reproduce in captivity. Birds for the colony were obtained from either the New York Zoological Park and Dallas Zoo or were wild-caught along the Maryland and Virginia coasts in 1972, 1973, and 1975. This report describes a die-off in the colony following a change in the origina of their food source. The data suggest that the mortality was diet-related, most likely caused by vitamin E deficiency. Excessive dietary thiaminase may have resulted in concurrent thiamine deficiency, but evidence for this is equivocal.

American Association of Zoo Veterinarians, Annual ↗