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At least 91 records · Page 5Linked to original sources
USGS2022

Population dynamics of Yellowstone Cutthroat Trout in Henrys Lake, Idaho

Yellowstone Cutthroat Trout (YCT) Oncorhynchus clarkii bouvieri is a species with significant ecological and recreational value. In many YCT fisheries, managers are tasked with balancing angler expectations and fish conservation. Henrys Lake supports a popular trophy trout fishery, but the increase of nonnative Utah Chub Gila atraria has caused concern for YCT. We summarized long-term trends in abundance, length structure, body condition, and growth of YCT to evaluate the effect of Utah Chub. Additionally, we investigated abiotic and biotic factors influencing YCT. We examined archived hard structures to provide a comprehensive evaluation of changes in age and growth of YCT in the system. We used stocking records and catch rates of Utah Chub and trout in Henrys Lake as covariates to explain changes in YCT catch rates and growth. Catch rates varied from 1.5 to 15.4 YCT per net night during the 2002 to 2020 sampling period, but we did not identify consistent patterns. Length structure was consistently dominated by stock- to quality-length fish, and we captured few fish >600 mm in total length. Relative weight of YCT was decreased from a mean ± standard deviation (SD) of 115.9 ± 16.5 in 2004 to 93.2 ± 8.2 in 2020. The age of YCT varied between 1 and 11 years; fish that we captured during 2010 to 2020 were the oldest. The majority of fish that we sampled were age 4 and younger. Total annual mortality of age-2 and older YCT was higher than other Cutthroat Trout populations (i.e., 0.70 during 2002 to 2010 and 0.60 during 2011 to 2020). Based on regression models, we identified positive relationships between catch rates of YCT, Brook Trout Salvelinus fontinalis, and Rainbow Trout Oncorhynchus mykiss × YCT hybrid trout. We observed negative relationships between growth of YCT and abundance of Utah Chub and Brook Trout. Although we identified negative relationships, YCT growth in recent decades is as fast as or faster than earlier time periods. Results from this research suggest that major changes in YCT population dynamics are not evident over the last 20 years. This study provides insight into the factors influencing an adfluvial trout population. In particular, results from this research may be useful for managers of systems where Utah Chub have been introduced.

Idaho↗
USGS2024

Glucocorticoid and glycemic responses to immune challenge in a viviparous snake afflicted with an emerging mycosis

Disease may be both a cause and consequence of stress, and physiological responses to infectious disease may involve stress coping mechanisms that have important fitness consequences. For example, glucocorticoid and glycemic responses may affect host fitness by altering resource allocation and use in hosts, and these responses may be affected by competing stressors. To better understand the factors that affect host responses to infection, we challenged the immune system of field acclimatized pygmy rattlesnakes, Sistrurus miliarius , with a sterile antigen, lipopolysaccharide (LPS), and measured the glucocorticoid and glycemic response in healthy non-reproductive snakes, snakes afflicted with an emerging mycosis (ophidiomycosis), and pregnant snakes. We hypothesized that LPS challenge would result in a glucocorticoid and glycemic response typical of the vertebrate acute phase response (APR), and therefore predicted that LPS challenge would result in an acute increase in plasma corticosterone (CORT) and a decline in plasma glucose in all individuals. Additionally, we hypothesized that the APR would be attenuated in individuals simultaneously coping with additional challenges to homeostasis (i.e., disease or reproduction). As predicted, immune challenge elicited an acute increase in plasma CORT and a decrease in plasma glucose. Snakes coping with ophidiomycosis and pregnant snakes were able to mount a robust glucocorticoid and hypoglycemic response to LPS challenge, which was contrary to our hypothesis. Our findings clarify directions of causality linking infection, glucocorticoids, and glucose, and emphasize the importance of future research examining the fitness consequences of interactions between stress and disease in wildlife threatened by emerging pathogens.

Journal of Experimental Biology↗
USGS2011

Effects of supplemental feeding and aggregation on fecal glucocorticoid metabolite concentrations in elk

Habitat modifications and supplemental feeding artificially aggregate some wildlife populations, with potential impacts upon contact and parasite transmission rates. Less well recognized, however, is how increased aggregation may affect wildlife physiology. Crowding has been shown to induce stress responses, and increased glucocorticoid (GC) concentrations can reduce immune function and increase disease susceptibility. We investigated the effects of supplemental feeding and the aggregation that it induces on behavior and fecal glucocorticoid metabolite concentrations (fGCM) in elk (Cervus elaphus) using observational and experimental approaches. We first compared fGCM levels of elk on supplemental feedgrounds to neighboring elk populations wintering in native habitats using data from 2003 to 2008. We then experimentally manipulated the distribution of supplemental food on feedgrounds to investigate whether more widely distributed food would result in lower rates of aggression and stress hormone levels. Contrary to some expectations that fed elk may be less stressed than unfed elk during the winter, we found that elk on feedgrounds had fecal GC levels at least 31% higher than non-feedground populations. Within feedgrounds, fGCM levels were strongly correlated with local measures of elk density (r 2 = 0.81). Dispersing feed more broadly, however, did not have a detectable effect on fGCM levels or aggression rates. Our results suggest that increases in aggregation associated with winter feedgrounds affects elk physiology, and the resulting increases in fGCM levels are not likely to be mitigated by management efforts that distribute the feed more widely. Additional research is needed to assess whether these increases in fGCMs directly alter parasite transmission and disease dynamics.

Journal of Wildlife Management↗
USGS2019

U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2017 annual report

The Wyoming Landscape Conservation Initiative (WLCI) was established in 2008 to address the scientific and conservation questions associated with land use changes because of energy development and other factors in southwest Wyoming. Over the past decade, partners from U.S. Geological Survey (USGS), State and Federal land management agencies, universities, and the public have collaborated to implement a long-term (defined here as more than 10 years), science-based program that assesses and enhances the quality and quantity of wildlife habitats in this region while facilitating responsible development. The USGS Science Team completes scientific research and develops tools that inform and support WLCI partner planning, decision making, and on-the-ground management actions. In fiscal year 2017, USGS published 18 products (including peer-reviewed journal articles, USGS series publications, and data releases), prepared an additional 7 products for publication, and presented 14 talks or posters at professional scientific meetings in addition to numerous informal presentations to WLCI partners at meetings and workshops. In this report, we summarize the science themes that describe USGS science for the WLCI and highlight work completed in fiscal year 2017 for each science theme. We also provide information on how USGS science is being used by land managers to better achieve habitat conservation objectives.

Wyoming↗
USGS2020

Preparing wildlife for climate change: How far have we come?

Global biodiversity is in unprecedented decline and on-the-ground solutions are imperative for conservation. Although there is a large volume of evidence related to climate change effects on wildlife, research on climate adaptation strategies is lagging. To assess the current state of knowledge in climate adaptation, we conducted a comprehensive literature review and evaluated 1,346 peer-reviewed publications for management recommendations designed to address the consequences of climate change on wildlife populations. From 509 publications, we identified 2,306 recommendations and employed both qualitative and quantitative methods for data analysis. Although we found an increase in the volume and diversity of recommendations since 2007, a focus on protected areas (26%, 596 of 2,306 recommendations) and the non-reserve matrix (12%, 276 of 2,306 recommendations) remained prominent in the climate adaptation literature. Common concepts include protected areas, invasive species, ecosystem services, adaptive management, stepping stones, assisted migration, and conservation easements. In contrast, only 1% of recommendations focused on reproduction ( n = 26), survival ( n = 14), disease ( n = 26), or human-wildlife conflict ( n = 24). Few recommendations reflected the potential for local-scale management interventions. We demonstrate limited advancement in preparing natural resource managers in climate adaptation at local, management-relevant scales. Additional research is needed to identify and evaluate climate adaptation strategies aimed at reducing the vulnerability of wildlife to contemporary climate change. © 2020 The Wildlife Society.

Journal of Wildlife Management↗
USGS2011

Occupancy and abundance of wintering birds in a dynamic agricultural landscape

Assessing wildlife management action requires monitoring populations, and abundance often is the parameter monitored. Recent methodological advances have enabled estimation of mean abundance within a habitat using presence–absence or count data obtained via repeated visits to a sample of sites. These methods assume populations are closed and intuitively assume habitats within sites change little during a field season. However, many habitats are highly variable over short periods. We developed a variation of existing occupancy and abundance models that allows for extreme spatio‐temporal differences in habitat, and resulting changes in wildlife abundance, among sites and among visits to a site within a field season. We conducted our study in sugarcane habitat within the Everglades Agricultural Area southeast of Lake Okeechobee in south Florida. We counted wintering birds, primarily passerines, within 245 sites usually 5 times at each site during December 2006–March 2007. We estimated occupancy and mean abundance of birds in 6 vegetation states during the sugarcane harvest and allowed these parameters to vary temporally or spatially within a vegetation state. Occupancy and mean abundance of the common yellowthroat ( Geothlypis trichas ) was affected by structure of sugarcane and uncultivated edge vegetation (occupancy = 1.00 [ = 0.96–1.00] and mean abundance = 7.9 [ = 3.2–19.5] in tall sugarcane with tall edge vegetation versus 0.20 [ = 0.04–0.71] and 0.22 [ = 0.04–1.2], respectively, in short sugarcane with short edge vegetation in one half of the study area). Occupancy and mean abundance of palm warblers ( Dendroica palmarum ) were constant (occupancy = 1.00, = 0.69–1.00; mean abundance = 18, = 1–270). Our model may enable wildlife managers to assess rigorously effects of future edge habitat management on avian distribution and abundance within agricultural landscapes during winter or the breeding season. The model may also help wildlife managers make similar management decisions involving other dynamic habitats such as wetlands, prairies, and even forested areas if forest management or fires occur during the field season.

Florida↗
USGS2011

Estimating occupancy dynamics in an anuran assemblage from Louisiana, USA

Effective monitoring programs are designed to track changes in the distribution, occurrence, and abundance of species. We developed an extension of Royle and Kéry's (2007) single species model to estimate simultaneously temporal changes in probabilities of detection, occupancy, colonization, extinction, and species turnover using data on calling anuran amphibians, collected from 2002 to 2006 in the Lower Mississippi Alluvial Valley of Louisiana, USA. During our 5-year study, estimates of occurrence probabilities declined for all 12 species detected. These declines occurred primarily in conjunction with variation in estimates of local extinction probabilities (cajun chorus frog [ Pseudacris fouquettei ], spring peeper [ P. crucifer ], northern cricket frog [ Acris crepitans ], Cope's gray treefrog [ Hyla chrysoscelis ], green treefrog [ H. cinerea ], squirrel treefrog [ H. squirella ], southern leopard frog [ Lithobates sphenocephalus ], bronze frog [ L. clamitans ], American bullfrog [ L. catesbeianus ], and Fowler's toad [ Anaxyrus fowleri ]). For 2 species (eastern narrowmouthed toad [ Gastrophryne carolinensis ] and Gulf Coast toad [ Incilius nebulifer ]), declines in occupancy appeared to be a consequence of both increased local extinction and decreased colonization events. The eastern narrow-mouthed toad experienced a 2.5-fold increase in estimates of occupancy in 2004, possibly because of the high amount of rainfall received during that year, along with a decrease in extinction and increase in colonization of new sites between 2003 and 2004. Our model can be incorporated into monitoring programs to estimate simultaneously the occupancy dynamics for multiple species that show similar responses to ecological conditions. It will likely be an important asset for those monitoring programs that employ the same methods to sample assemblages of ecologically similar species, including those that are rare. By combining information from multiple species to decrease the variance on estimates of individual species, our results are advantageous compared to single-species models. This feature enables managers and researchers to use an entire community, rather than just one species, as an ecological indicator in monitoring programs.

Louisiana↗
USGS1988

Nonhunting mortality in sandhill cranes

Records of 170 sandhill cranes ( Grus canadensis ) necropsied at the National Wildlife Health Research Center, Wisconsin, from 1976 through 1985 were reviewed as representative samples to determine causes of nonhunting mortality in the mid-continent and Rocky Mountain populations of sandhill cranes. Avian cholera, avian botulism, and ingestion of mycotoxins were leading causes of nonhunting mortality. Hailstorms, lightning, lead poisoning, predation, avian tuberculosis, and collisions with power lines also killed cranes.

Journal of Wildlife Management↗
USGS2023

Isothermal recombinant polymerase amplification and CRIPSR (CAS12A) assay detection of Renibacterium salmoninarum as an example for wildlife pathogen detection in environmental DNA samples

Improving rapid detection methods for pathogens is important for research as we collectively aim to improve the health of ecosystems globally. In the northern hemisphere, the success of salmon ( Oncorhynchus spp.) populations is vitally important to the larger marine, aquatic, and terrestrial ecosystems they inhabit. This has led to managers cultivating salmon in hatcheries and aquaculture to bolster their populations, but young salmon face many challenges, including diseases such as bacterial kidney disease (BKD). Early detection of the BKD causative agent, Renibacterium salmoninarum , is useful for managers to avoid outbreaks in hatcheries and aquaculture stocks to enable rapid treatment with targeted antibiotics. Isothermal amplification and CRIPSR-Cas12a systems may enable sensitive, relatively rapid, detection of target DNA molecules from environmental samples compared to quantitative PCR (qPCR) and culture methods. We used these technologies to develop a sensitive and specific rapid assay to detect R. salmoninarum from water samples using isothermal recombinase polymerase amplification (RPA) and an AsCas12a RNA-guided nuclease detection. The assay was specific to R. salmoninarum (0/10 co-occurring or closely related bacteria detected) and sensitive to 0.0128 pg/µL of DNA (approximately 20–40 copies/µL) within 10 min of Cas activity. This assay successfully detected R. salmoninarum environmental DNA in 14/20 water samples from hatcheries with known quantification for the pathogen via previous qPCR (70% of qPCR-positive samples). The RPA-CRISPR/AsCas12a assay had a limit of detection (LOD) of >10 copies/µL in the hatchery water samples and stochastic detection below 10 copies/µL, similar to but slightly higher than the qPCR assay. This LOD enables 37 C isothermal detection, potentially in the field, of biologically relevant levels of R. salmoninarum in water. Further research is needed to develop easy-to-use, cost-effective, sensitive RPA/CRISPR-AsCas12a assays for rapidly detecting low concentrations of wildlife pathogens in environmental samples.

Journal of Wildlife Diseases↗
USGS2011

Spatial patch occupancy patterns of the Lower Keys marsh rabbit

Reliable estimates of presence or absence of a species can provide substantial information on management questions related to distribution and habitat use but should incorporate the probability of detection to reduce bias. We surveyed for the endangered Lower Keys marsh rabbit ( Sylvilagus palustris hefneri ) in habitat patches on 5 Florida Key islands, USA, to estimate occupancy and detection probabilities. We derived detection probabilities using spatial replication of plots and evaluated hypotheses that patch location (coastal or interior) and patch size influence occupancy and detection. Results demonstrate that detection probability, given rabbits were present, was <0.5 and suggest that naïve estimates (i.e., estimates without consideration of imperfect detection) of patch occupancy are negatively biased. We found that patch size and location influenced probability of occupancy but not detection. Our findings will be used by Refuge managers to evaluate population trends of Lower Keys marsh rabbits from historical data and to guide management decisions for species recovery. The sampling and analytical methods we used may be useful for researchers and managers of other endangered lagomorphs and cryptic or fossorial animals occupying diverse habitats.

Florida↗
USGS2001

Antibody response to rabies vaccination in captive and freeranging wolves (Canis lupus)

Fourteen captive and five free-ranging Minnesota gray wolves (Canis lupus) were tested for the presence of rabies virus neutralizing antibodies (RVNA) after vaccination with an inactivated canine rabies vaccine. Blood was collected from all wolves prior to vaccination and at 1 mo postvaccination (PV) and from all captive and three wild wolves at 3 mo PV. In addition, one free-ranging wolf was sampled at 4 mo PV, and two free-ranging wolves were sampled at 6 mo PV. All wolves were seronegative prior to vaccination. RVNA were detected in 14 (100%) captive wolves and in four of five (80%) free-ranging wolves. The geometric mean titer of the captive wolves at 1 mo PV was significantly higher (P = 0.023) than in the free-ranging wolves. Five of 13 (38.5%) captive wolves and none of the three (0%) free-ranging wolves had measurable RVNA at 3 mo PV. No measurable RVNA were detected in the serum samples collected from the free-ranging wolves at 4 and 6 mo PV. These results should be interpreted with caution because of the small number of free-ranging wolves tested. Further research is needed to properly assess immune function and antibody response to vaccination in captive wolves in comparison with their free-ranging counterparts.

Journal of Zoo and Wildlife Medicine↗
USGS1986

Mid-winter food use and body weights of mallards and wood ducks in Mississippi

We obtained esophageal food samples from 311 mallards (Anas platyrhynchos) and 94 wood ducks (Aix sponsa) and body weights from 2,118 mallards and 315 wood ducks in western Mississippi during December and January 1979-83. On average, mallards ingested 3.0% animal food, principally aquatic invertebrates, and 97.0% plant food. Rice, soybeans, and seeds of 'moist soil' plants provided 41.3, 41.6, and 10-11% of the total food intake. Wood ducks ingested nearly 100% plant food, of which 23.4% was soybeans and 74.3% was acorns from Nuttall (Quercus nuttallii), water (Q. nigra), and willow oaks (Q. phellos). Mallard food use varied with water conditions; the use of rice decreased and soybeans increased during 1980-81 when cumulative November-January precipitation was < 50% of normal. Wood duck food use varied with habitat; the diet included more acorns at sites having larger acreages of intact bottomland hardwood forest. Mallard and wood duck body weights varied within and among winters. Mallard weights decreased by about 2% from December to January each year. We considered this a regulated loss, whereas we attributed increases and decreases of 4-5% in average weights during wet and dry winters to changes in feeding opportunities associated with winter precipitation. Wood duck weights followed similar trends. We concluded that continued drainage in the Mississippi Delta will adversely affect waterfowl foraging opportunities, and that research on winter feeding ecology will progress more rapidly if we develop an understanding of the foraging efficiencies associated with alternate food resources.

Mississippi↗
USGS2017

No substitute for survival: Perturbation analyses using a Golden Eagle population model reveal limits to managing for take

Conserving populations of long-lived birds of prey, characterized by a slow life-history (e.g., high survival and low reproductive output), requires a thorough understanding of how variation in their vital rates differentially affects population growth. Stochastic population modeling provides a framework for exploring variation in complex life histories to better understand how environmental and demographic variation within individual vital rates affects population dynamics. Specifically, we used life-stage simulation analysis (LSA) to identify those life-history characteristics that most affect population growth and are amenable to management actions. The Golden Eagle ( Aquila chrysaetos ) is a wide-ranging raptor of conservation concern, which has been adopted as a focal species for conservation planning. Golden Eagle population trends in western North America currently appear stable. Yet an expanding human footprint that may increase mortality stimulated our investigation into the ability of populations to sustain reduced survival. We fit mixed-effects models to published estimates of vital rates to estimate the mean and process variation of productivity (young fledged per pair) and survival for use in a LSA framework. As expected, breeding adult survival had the greatest relative effect on population growth, though productivity explained the most variation in growth. Based on perturbation analyses, we demonstrate that even minor reductions in breeding adult survival (<4.5%) caused otherwise stable populations to decline. Despite its importance, precise estimates of spatial and temporal variation in breeding adult survival are poorly documented. Importantly, we found that the ability for increases in reproductive output to compensate for decreased survival was very limited. To maintain stable populations, declines in survival >4% required increases in productivity that generally exceed the evolutionary potential for Golden Eagles. Our findings support the current U.S. Fish and Wildlife conservation strategy which mitigates eagle “take” via efforts to reduce mortality elsewhere.

Journal of Raptor Research↗
USGS2023

Integrated rangeland fire management strategy actionable science plan completion assessment — Sagebrush and sage-grouse topic, 2015–20

Loss and degradation of sagebrush rangelands due to an accelerated invasive annual grass-wildfire cycle and other stressors are significant management, conservation, and economic issues in the western United States. These sagebrush rangelands comprise a unique biome spanning 11 states, support over 350 wildlife species, and provide important ecosystem services that include stabilizing the economies of western communities. Impacts to sagebrush ecosystem processes over large areas due to the annual grass-wildfire cycle necessitated the development of a coordinated, science-based strategy for improving efforts to achieve long-term protection, conservation, and restoration of sagebrush rangelands, which was framed in 2015 under the Integrated Rangeland Fire Management Strategy (IRFMS). Central to this effort was the development of an Actionable Science Plan (Plan) that identified 37 priority science needs (Needs) for informing the actions proposed under the 5 topics (Fire, Invasives, Restoration, Sagebrush and Sage-Grouse, Climate and Weather) that were part of the collective focus of the IRFMS. Notable keys to this effort were identification of the Needs co-produced by managers and researchers, and a focus on resulting science being “actionable.” Substantial investments aimed at fulfilling the Needs identified in the Plan have been made since its release in 2016. While the state of the science has advanced considerably, the extent to which knowledge gaps remain relative to identified Needs is relatively unknown. Moreover, new Needs have likely emerged since the original strategy as results from actionable science reveal new questions and possible (yet untested) solutions. A quantifiable assessment of the progress made on the original science Needs can identify unresolved gaps and new information that can help inform prioritization of future research efforts. This report details a systematic literature review that evaluated how well peer-reviewed journal articles and formal technical reports published between January 1, 2015, and December 31, 2020, addressed nine needs (hereinafter, “Needs”) identified under the Sagebrush and Sage-Grouse topic in the Plan. The topic outlined research Needs broadly focused on understanding sagebrush rangelands and population dynamics important for the conservation and management of sage-grouse and other sagebrush-reliant wildlife species. We established the level of progress towards addressing each Need following a standardized set of criteria, and developed summaries detailing how research objectives nested within Needs identified in the Plan (‘Next Steps’) were either addressed well, partially addressed or remain outstanding (in other words, addressed poorly) in the literature through 2020. Our searches resulted in the inclusion of 333 science products that at least partially addressed a Need identified in the Sagebrush and Sage-Grouse topic. The Needs that were well and partially addressed included: development of biome-wide mapping techniques that provide regularly updated grassland and shrubland vegetation layers (Need 4); generation of spatially explicit greater sage-grouse habitat suitability and population models (Need 5); identification of greater sage-grouse seasonal habitats (Need 6); identification of thresholds for the extent of threats, especially conifer expansion, above which greater sage-grouse and other sagebrush-obligate species cannot persist (Need 8); and studies of sagebrush community dynamics as those relate to management and restoration of sagebrush rangelands (Need 9). Needs addressed poorly included: investigations of factors conducive and restrictive to greater sage-grouse movement patterns and population connectivity (Need 1); investigations of livestock and other large ungulate (for example, feral horse) grazing effects on greater sage-grouse populations and habitats (Need 2); identification of thresholds of disturbance (especially renewable energy developments) below which greater sage-grouse and other sagebrush reliant species are not impacted (Need 3); and studies of habitat relationships for sagebrush-reliant species other than greater sage-grouse, songbirds, and small mammals (Need 7). The information provided in this assessment will assist updating the Plan along with other science strategies.

western United States↗
USGS1989

Acid rain publications by the U.S. Fish and Wildlife Service, 1979-1989

Pollution of aquatic and terrestrial ecosystems has been a concern to society since the burning of fossil fuels began in the industrial revolution. In the past decade or so, this concern has been heightened by evidence that chemical transformation in the atmosphere of combustion by-products and subsequent long-range transport can cause environmental damage in remote areas. The extent of this damage and the rates of ecological recovery were largely unknown. "Acid rain" became the environmental issue of the 1980's. To address the increasing concerns of the public, in 1980 the Federal government initiated a 10-year interagency research program to develop information that could be used by the President and the Congress in making decisions for emission controls. The U.S. Fish and Wildlife Service has been an active participant in acid precipitation research. The Service provided support to a number of scientific conferences and forums, including the Action Seminar on Acid Precipitation held in Toronto, Canada, in 1979, an international symposium on Acidic Precipitation and Fishery Impacts in Northeastern North America in 1981, and a symposium on Acidic Precipitation and Atmospheric Deposition: A Western Perspective in 1982. These meetings as well as the growing involvement with the government's National Acidic Precipitation Assessment Program placed the Service in the lead in research on the biological effects of acidic deposition. Research projects have encompassed water chemistry, aquatic invertebrates, amphibians, fish, and waterfowl. Water quality surveys have been conducted to help determine the extent of acid precipitation effects in the northeast, Middle Atlantic, and Rocky Mountain regions. In addition to lake and stream studies, research in wetland and some terrestrial habitats has also been conducted. Specific projects have addressed important sport species such as brook trout (Salvelinus fontinalis), Atlantic salmon (Salmo salar), and striped bass (Morone saxatilis). Trace metal accumulation in fish has been investigated and a symposium sponsored on related work. U.S> Fish and Wildlife Service scientists serve as advisors and participants in research being conducted by industry, nonprofit groups, State and other Federal agencies. Researcher have worked closely with colleagues in Canada, England, Norway, Scotland, the Soviet Union, and Sweden to gain additional understanding of the problem. In 1982, the Service implemented a mitigation research program to provide resource managers with information to help them protect sensitive ecosystems, and rehabilitation methods for resources already affected by acidification. An international workshop was convened to outline the research needs. Several conferences were organized to develop appropriate field and laboratory procedures. Scientists with the mitigation research program are evaluating the ecological effects of liming (addition of base material) surface waters and surrounding watershed to provide buffering against acidic inputs. Through long-term cooperative project with States and other organizations, investigations are studying possible abatement methods for regions most affected by acidic deposition. To date, more than 200 reports the describe these studies have been published. These products include conference proceedings, journal articles, and in-house scientific publications. An education poster describing the effects of acid rain on aquatic ecosystems was developed and distributed to individuals, conservations and State organizations, and the public education system. This annotated bibliography lists current publications by Service authors, cooperators, or contractors on acid rain and related quality. Entire are arranged alphabetically by author surname. For further information about the research program, contact the U.S. Fish and Wildlife Service, Acid Precipitation Section, National Fishery Research Center -- Leetown, Box 700, Kearneysville, WV 25430.

Biological Report↗
USGS1974

Salmonellosis in a captive heron colony

Salmonellosis caused by Salmonella typhimurium was one of several factors responsible for losses among young herons being held at the Patuxent Wildlife Research Center. The infection was demonstrated in five black-crowned night herons ( Nycticorax nycticorax ), three common egrets ( Casmerodius albus ), two little blue herons ( Florida caerulea ), one cattle egret ( Bubulcus ibis ), one snowy egret ( Leucophoyx thula ) and one Louisiana heron ( Hydranassa tricolor ). The disease was characterized by emaciation, focal liver necrosis, and frequently by a caseo-necrotic enteritis.

Maryland↗
USGS2016

Predictors of breeding site occupancy by amphibians in montane landscapes

Ecological relationships and processes vary across species’ geographic distributions, life stages and spatial, and temporal scales. Montane landscapes are characterized by low wetland densities, rugged topographies, and cold climates. Consequently, aquatic-dependent and low-vagility ectothermic species (e.g., pool-breeding amphibians) may exhibit unique ecological associations in montane landscapes. We evaluated the relative importance of breeding- and landscape-scale features associated with spotted salamander ( Ambystoma maculatum ) and wood frog ( Lithobates sylvaticus ) wetland occupancy in Maine's Upper Montane-Alpine Zone ecoregion, and we determined whether models performed better when the inclusive landscape-scale covariates were estimated with topography-weighted or circular buffers. We surveyed 135 potential breeding sites during May 2013–June 2014 and evaluated environmental relationships with multi-season implicit dynamics occupancy models. Breeding site occupancy by both species was influenced solely by breeding-scale habitat features. Spotted salamander occupancy probabilities increased with previous or current beaver ( Castor canadensis ) presence, and models generally were better supported when the inclusive landscape-scale covariates were estimated with topography-weighted rather than circular buffers. Wood frog occupancy probabilities increased with site area and percent shallows, but neither buffer type was better supported than the other. Model rank order and support varied between buffer types, but model inferences did not. Our results suggest pool-breeding amphibian conservation in montane Maine include measures to maintain beaver populations and large wetlands with proportionally large areas of shallows ≤1-m deep. Inconsistencies between our study and previous studies substantiate the value of region-specific research for augmenting species’ conservation management plans and suggest the application of out-of-region inferences may promote ineffective conservation.

Maine↗
USGS2014

A bivalent scale for measuring crowding among deer hunters

One factor that may influence satisfaction in outdoor recreation is crowding, which historically has been defined as a negative evaluation of the density of other participants. While this definition is suitable for most scenarios, there are circumstances where encounters with others in the area are evaluated positively and thus contribute to the satisfaction of the participant. To adequately describe this phenomenon we suggest a more inclusive measurement of crowding that allows for both positive and negative evaluations of participant density to more accurately explore the relationship between crowding and satisfaction. We identified a sub-group of deer hunters who negatively evaluated the low density of other hunters, which reduced their satisfaction with their overall hunting experience. The methodology for measuring crowding in recreation research may have an important effect in identifying the relationship crowding has with other relevant variables as well as management implications.

South Dakota↗