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The U.S. Geological Survey (USGS) is focused on the development of early detection and effective response tools that promote an adaptive management approach to chronic wasting disease (CWD). USGS scientists across the United States are working to understand the biology of CWD, assess and predict the spread and persistence in wildlife and the environment, and develop tools for early detection and control.
The Willamette Valley Ecoregion (as defined by Omernik, 1987; U.S. Environmental Protection Agency, 1997) covers approximately 14,458 km² (5,582 mi 2 ), making it one of the smallest ecoregions in the conterminous United States. The long, alluvial Willamette Valley, which stretches north to south more than 193 km and ranges from 32 to 64 km wide, is nestled between the sedimentary and metamorphic Coast Ranges (Coast Range Ecoregion) to the west and the basaltic Cascade Range (Cascades Ecoregion) to the east (fig. 1). The Lewis and Columbia Rivers converge at the ecoregion’s northern boundary in Washington state; however, the majority of the ecoregion falls within northwestern Oregon. Interstate 5 runs the length of the valley to its southern boundary with the Klamath Mountains Ecoregion. Topography here is relatively flat, with elevations ranging from sea level to 122 m. This even terrain, coupled with mild, wet winters, warm, dry summers, and nutrient-rich soil, makes the Willamette Valley the most important agricultural region in Oregon. Population centers are concentrated along the valley floor. According to estimates from the Oregon Department of Fish and Wildlife (2006), over 2.3 million people lived in Willamette Valley in 2000. Portland, Oregon, is the largest city, with 529,121 residents (U.S. Census Bureau, 2000). Other sizable cities include Eugene, Oregon; Salem (Oregon’s state capital); and Vancouver, Washington. Despite the large urban areas dotting the length of the Willamette Valley Ecoregion, agriculture and forestry products are its economic foundation (figs. 2,3). The valley is a major producer of grass seed, ornamental plants, fruits, nuts, vegetables, and grains, as well as poultry, beef, and dairy products. The forestry and logging industries also are primary employers of the valley’s rural residents (Rooney, 2008). These activities have affected the watershed significantly, with forestry and agricultural runoff contributing to river sedimentation and decreased water quality in the Willamette River and its tributary streams (Oregon Department of Fish and Wildlife, 2006). Recent years have seen a marked decline in forest health related to the increased frequency of multiyear droughts. Insect damage and other diseases also are present; however, drought- related water stress is the primary factor in coniferous-tree mortality (Oregon Department of Forestry, 2008). Trees most at risk include Douglas-fir ( Pseudotsuga menziesii ), grand fir ( Abies grandis ), and western red cedar ( Thuja plicata ). Overstocking by timber companies and planting on sites with poor conditions increase susceptibility. Over time, these problems may lead to changes in planting practices and the use of more drought-tolerant species such as ponderosa pine ( Pinus ponderosa ).
North America's protected lands harbor biodiversity and provide habitats where species threatened by a variety of stressors in other environments can thrive. Yet disease, climate change, and other threats are not limited by land management boundaries and can interact with conditions within protected landscapes to affect sensitive populations. We examined the population dynamics of a boreal toad ( Anaxyrus boreas boreas ) metapopulation at a wildlife refuge in northwestern Montana, USA, over a 16‐year period (2003–2018). We used robust design capture‐recapture models to estimate male population size, recruitment, and apparent survival over time and in relation to the amphibian chytrid fungus ( Batrachochytrium dendrobatidis ). We estimated female population size in years with sufficient captures. Finally, we examined trends in male and female toad body size and condition. We found no evidence of an effect of disease or time on male toad survival but detected a strong negative trend in recruitment of new males to the population. Estimates of male and female abundance decreased over time. Body size of males and females was inversely related to estimated population size, consistent with reduced recruitment to replace adults, but body condition of adult males was only weakly associated with abundance. Together, these results describe the demography of a near‐extirpation event, and point to dramatic decreases in the recruitment of new individuals to the breeding population as the cause of this decline. We surmise that processes related to the restoration of historical hydrology within the refuge adversely affected amphibian breeding habitat, and that these changes interacted with disease, life history, and other factors to restrict the recruitment of new individuals to the breeding population over time. Our results point to challenges in understanding and predicting factors that influence population change and highlight that current metrics for assessing population status can have limited predictive ability. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.
We summarized the cause of death for 2,980 bald eagles ( Haliaeetus leucocephalus ) and 1,427 golden eagles ( Aquila chrysaetos ) submitted to the National Wildlife Health Center in Madison, Wisconsin, USA, for diagnosis between 1975 and the beginning of 2013. We compared the proportion of eagles with a primary diagnosis as electrocuted, emaciated, traumatized, shot or trapped, diseased, poisoned, other, and undetermined among the 4 migratory bird flyways of the United States (Atlantic, Mississippi, Central, and Pacific). Additionally, we compared the proportion of lead-poisoned bald eagles submitted before and after the autumn 1991 ban on lead shot for waterfowl hunting. Trauma and poisonings (including lead poisoning) were the leading causes of death for bald eagles throughout the study period, and a greater proportion of bald eagles versus golden eagles were diagnosed as poisoned. For golden eagles, the major causes of mortality were trauma and electrocution. The proportion of lead poisoning diagnoses for bald eagles submitted to the National Wildlife Health Center displayed a statistically significant increase in all flyways after the autumn 1991 ban on the use of lead shot for waterfowl hunting. Thus, lead poisoning was a significant cause of mortality in our necropsied eagles, suggesting a continued need to evaluate the trade-offs of lead ammunition for use on game other than waterfowl versus the impacts of lead on wildlife populations. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
Prions cause fatal neurodegenerative diseases and exhibit remarkable durability, which engenders a wide array of potential exposure scenarios. In chronic wasting disease of deer, elk, moose, and reindeer and in scrapie of sheep and goats, prions are transmitted via environmental routes and the ability of plants to accumulate and subsequently transmit prions has been hypothesized, but not previously demonstrated. Here, we establish the ability of several crop and other plant species to take up prions via their roots and translocate them to above-ground tissues from various growth media including soils. We demonstrate that plants can accumulate prions in above-ground tissues to levels sufficient to transmit disease after oral ingestion by mice. Our results suggest plants may serve as vectors for prion transmission in the environment—a finding with implications for wildlife conservation, agriculture, and public health.
A devastating, emergent disease afflicting hibernating bats has pread from the northeast to the mid-Atlantic region of the United States at an alarming rate. Since the winter of 2006-2007, hundreds of thousands of insect-eating bats from at least nine states have died from this new disease, named White-Nose Syndrome (WNS). The disease is named for the white fungus often seen on the muzzles, ears, and wings of bats. This disease poses a threat to cave hibernating bats of the United States and potentially all temperate regions of the world. USGS scientists from the National Wildlife Health Center (NWHC) and the Fort Collins Science Center (FORT), in collaboration with the New York State Department of Environmental Conservation, the U.S. Fish and Wildlife Service, and others have linked a newly described, cold-loving fungus to WNS.
Dispersal distances and their distribution pattern are important to understanding such phenomena as disease spread and gene flow, but oftentimes dispersal characteristics are modeled as a fixed trait for a given species. We found that dispersal distributions differ for spring and autumn dispersals of yearling male white-tailed deer (Odocoileus virginianus) but that combined data can be adequately modeled based on a log-normal distribution. We modeled distribution of dispersal distances from 3 distinct populations in Pennsylvania and Maryland, USA, based on the relationship between percent forest cover and mean dispersal distance and the relationship between mean and variance of dispersal distances. Our results suggest distributions of distances for dispersing yearling male white-tailed deer can be modeled by simply measuring a readily obtained landscape metric, percent forest cover, which could be used to create generalized spatially explicit disease or gene.
This study is an experimental demonstration of lethal mobilization of DDT by brown-headed cowbirds ( Molothrus ater ) and the effects of food deprivation on the distribution and loss of DDT, DDD, and DDE. The principal experimental group consisted of 20 birds fed a dietary dosage of 100 ppm of DDT for 13 days. After 2 days of full rations of untreated food, they were subjected to food restriction. Food was reduced to 43 percent of normal. Seven of the 20 birds died within 4 days. No birds died in the three control groups, treated as follows: ( 1 ) 20 birds fed 100 ppm DDT for 13 days and full rations of untreated food thereafter, (2) 20 birds fed only untreated food but subjected to food restriction, and (3) 20 birds fed full rations of untreated food throughout. In a pilot study, birds were fed 100, 200, or 300 ppm of DDT and subjected to two periods of food restriction, the first of these immediately after dosage ceased and the second 4 months later. DDT-dosed birds from all dosage levels died in each period of food restriction. Before the weight loss that accompanied food restriction, the brains of DDT-dosed birds had concentrations of DDT and DDD that were far below the lethal range. Concentrations increased rapidly to lethal levels. In these birds, DDT in carcasses decreased while DDD increased. DDT-dosed birds that died during food restriction lost 16 percent of their total body burden of DDT + DDD + DDE, 21 percent of their weight, and 81 percent of their fat. The DDT-dosed birds that were subjected to food restriction but survived lost a significantly greater proportion of their body burden of residues than similarly dosed birds not subjected to weight loss. Brain levels of DDT and DDD in birds that died during food restriction soon after dosage did not differ significantly from brain levels of birds that died in a period of food restriction 4 months after dosage. Concentrations of DDE were significantly higher in the latter group, although they were lower than concentrations considered to be lethal. In contrast, carcass levels of DDT and DDD were significantly lower, and DDE was only slightly higher, in the birds that died in the second period of food restriction. It is concluded that stored DDT residues present a hazard to birds, which utilize stored fat during periods of stress due to reproduction, cold weather, disease, injury, limited food supply, or migration.
Neurotropic velogenic Newcastle disease (NVND) occurred in juvenile double-crested cormorants, Phalacrocorax auritus , simultaneously in nesting colonies in Minnesota, North Dakota, South Dakota, and Nebraska and in Lakes Michigan, Superior, Huron, and Ontario during the summer of 1992. Mortality as high as 80%-90% was estimated in some of the nesting colonies. Clinical signs observed in 4- to -6 wk-old cormorants included torticollis, tremors, ataxia, curled toes, and paresis or weakness of legs, wings or both, which was sometimes unilateral. No significant mortality or unusual clinical signs were seen in adult cormorants. Necropsy of 88 cormorants yielded no consistent gross observations. Microscopic lesions in the brain and spinal cord were consistently present in all cormorants from which Newcastle disease virus (NDV) was isolated. Characteristic brain lesions provided rapid identification of new suspect sites of NVND. Lesions were also present in the heart, kidney, proventriculus, spleen, and pancreas but were less consistent or nonspecific. NDV was isolated at the National Wildlife Health Center from 27 of 93 cormorants tested. Virus was most frequently isolated from intestine or brain tissue of cormorants submitted within the first 4wk of the epornitic. Sera collected from cormorants with neurologic signs were consistently positive for NDV antibody.The NDV isolate from cormorants was characterized as NVND virus at the National Veterinary Services Laboratories Ames, Iowa. The NVND virus was also identified as the cause of neurologic disease in a North Dakota turkey flock during the summer of 1992. Although no virus was isolated from cormorants tested after the first month of submissions, brain and spinal cord lesions characteristic of NVND were observed in cormorants from affected sites for 2 mo, at which time nesting colonies dispersed and no more submissions were received. Risk to susceptible populations of both wild avian species and domestic poultry makes early recognition and confirmation of NVND in wild birds a priority.
The Department of the Interior protects sensitive habitats amounting to about 3,600,000 acres of coral reefs and other submerged lands. These reefs are important ecosystems in 13 National Wildlife Refuges, 10 National Parks and in certain territorial waters such as the Wake Atoll.
Chronic wasting disease (CWD) is a major concern for the management of North American cervid populations. This fatal prion disease has led to declines in populations which have high CWD prevalence and areas with both high and low infection rates have experienced economic losses in wildlife recreation and fears of potential spill-over into livestock or humans. Research from human and veterinary medicine has established that the prion protein gene ( Prnp ) encodes the protein responsible for transmissible spongiform encephalopathies (TSEs). Polymorphisms in the Prnp gene can lead to different prion forms that moderate individual susceptibility to and progression of TSE infection. Prnp genes have been sequenced in a number of cervid species including those currently infected by CWD (elk, mule deer, white-tailed deer, moose) and those for which susceptibility is not yet determined (caribou, fallow deer, sika deer). Over thousands of sequences examined, the Prnp gene is remarkably conserved within the family Cervidae; only 16 amino acid polymorphisms have been reported within the 256 amino acid open reading frame in the third exon of the Prnp gene. Some of these polymorphisms have been associated with lower rates of CWD infection and slower progression of clinical CWD. Here we review the body of research on Prnp genetics of North American cervids. Specifically, we focus on known polymorphisms in the Prnp gene, observed genotypic differences in CWD infection rates and clinical progression, mechanisms for genetic TSE resistance related to both the cervid host and the prion agent and potential for natural selection for CWD-resistance. We also identify gaps in our knowledge that require future research.
Hawai‘i has some of the most endangered avian species in the world, which face numerous threats from habitat loss, disease, climate change, and introduced species. This report details the results of a two-year productivity study of all forest bird species at Hakalau National Wildlife Refuge, Hawai‘i Island. We found and monitored nests from seven native species and three common non-native species of forest birds at three sites across the refuge. In addition to gathering important baseline information on productivity of forest birds, we examined differences in productivity between years, sites, and as a function of nest height. The weather differed greatly between the two years, with much more rain occurring in 2014. The daily survival rate (DSR) of nests was found to have an inverse relationship with the amount of rainfall, and accordingly was much lower in 2014 compared to 2013. Nest success was lower at a regenerating forest site compared with mature rainforest, indicating negative environmental factors affecting nest success may be exacerbated in reforested areas which have lower canopies. Nest success was also impacted by nest height, with a positive relationship in the drier 2013, and a negative relationship in 2014 for the canopy nesting honeycreepers. The large difference in weather and DSR between years illustrates the need for long term demographic studies that can capture the vital rates of this community of birds.
Over the last few decades, freshwater turtles have become more common in the illegal wildlife trade because of growing global demand. Illegally traded turtles may be intercepted by several different agencies with separate jurisdictions. When turtles are confiscated, uncertainties may make releasing them back to the wild difficult. We used tools from decision analysis to achieve the following three objectives: (1) map elements of the decision process and their relationships in the illegal turtle trade using conceptual models, (2) outline the linked decisions for turtle confiscation and repatriation using decision trees, and (3) evaluate the decision trees for two example scenarios, one with moderate uncertainty and one with high uncertainty. We used the wood turtle ( Glyptemys insculpta ) as a case study, which is a species of conservation concern in part due to illegal wildlife trafficking. We conducted 23 semi-structured interviews of decision makers in law enforcement, biologists, land managers, and zoo staff. Interviews revealed that decisions regarding the disposition of confiscated turtles are complicated by uncertainty in disease status and origin. Decision makers that handle confiscated turtles also recognize that their decisions are often made in sequence and dependent on the outcome of antecedent decisions. In evaluating our decision trees, we found that the optimal decisions for example scenarios were similar and insensitive to uncertainty. Future applications of the decision trees by decision makers would involve a decision analyst to parameterize and interpret the choices and consequences involved in working through these decision trees. Collectively, our work shows how the use of decision trees can help structure and evaluate risky decisions for repatriating confiscated wildlife.
No abstract available.
No abstract available.
The normal values used as a diagnostic tool and for comparison of cranes were established in the early 1970's. In that early study, no effort was made to look at factors such as age, sex, or subspecies. In addition, during the early study disease problems (primarily disseminated visceral coccidiosis) and nutritional problems were undiagnosed and uncontrolled. For 2 years during the annual health examinations of cranes at the USGS Patuxent Wildlife Research Center (Patuxent), we collected blood from healthy cranes for analysis. We found significant differences between the values reported from the 1970's and the values seen in this study for 8 blood parameters for Florida sandhill cranes (Grus canadensis pratensis), 6 blood parameters for greater sandhill cranes (G. c. tabida), and 6 blood parameters for whooping cranes (Grus americana). In addition, there were significant differences for some hematology and serum chemistry values based on the age of the cranes.
Mosquitoes and the pathogens they transmit are ubiquitous throughout most of the temperate and tropical regions of the world. The natural and pre-European distribution and diversity of mosquitoes and mosquito-borne diseases throughout much of the Pacific region, however, depicts a depauperate and relatively benign fauna reinforcing the dream of “paradise regained”. In the central and South Pacific few mosquito species were able to colonize the remotest islands and atolls. Native mosquitoes are limited to a few far-ranging species and island endemics are typically restricted to the genera of Aedes and Culex . Only lymphatic filariasis appears to have been present as an endemic mosquito-borne disease before European contact. In nearby Australia, however, some 242 species of mosquitoes are known to occur and more than 70 arboviruses have been identified (Mackenzie 1999). In this regard Australia is more similar to the rest of the tropic and subtropical world than the smaller islands of Oceania. In our ever-shrinking world of global commerce, military activity and travel, the nature of mosquito-borne disease in the Pacific was bound to change. This paper is a brief summary of introduced mosquitoes in the Pacific and their potential impacts on human and wildlife health.
An increased societal focus on wildlife as food and recent policy deliberations regarding legal markets for wild-harvested meat are encouraging wildlife managers and researchers to examine the amount, use, and distribution of meat yielded through recreational hunting. We used responses to questions on the Michigan Deer Harvest Study to estimate the maximum yield of edible venison and assess hunters’ sharing behaviors. We estimated 11,402–14,473 metric tons of edible venison were procured during the 2013 hunting season. Of hunters who harvested a deer, 85% shared their venison. Hunters who shared did so with an average of 5.6 people (SD = 4.5). Sharing occurred most frequently within tight social networks: members of hunters’ households (69%), relatives (52%), and friends, neighbors, or coworkers (50%). In the absence of legal markets, venison is distributed widely by hunters and greatly amplifies the number of people benefiting from hunting. Nonetheless, we also identified the potential breadth of exposure to disease or contaminants from wild-harvested meat.