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At least 649 records · Page 36Linked to original sources

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↗

USGS2022

Disease and secondary sexual traits: Effects of pneumonia on horn size of bighorn sheep

Secondary sexual traits (e.g., horns and antlers) have ecological and evolutionary importance and are of management interest for game species. Yet, how these traits respond to emerging threats like infectious disease remains underexplored. Infectious pneumonia threatens bighorn sheep ( Ovis canadensis ) populations across North America and we hypothesized it may also reduce horn growth in male sheep. We assess the effect of pneumonia on horn size in male bighorn sheep using 12 herd datasets from across the western United States that had horn growth and disease data. Disease resulted in 12–35% reduction in increment (yearly) length and 3–13% reduction in total horn length in exposed individuals. The disease effect was prolonged when pathogens continued to circulate in sheep populations. Further, disease likely delays the age at which horns reach ¾-curl and prevents achievement of full-curl. This is further evidenced with 6 of the 12 herds experiencing an increase in average age at harvest following die-off events.

Colorado, Idaho, Montana, Utah, Washington, Wyomin↗

USGS2011

Population fragmentation and inter-ecosystem movements of grizzly bears in Western Canada and the Northern United States

Population fragmentation compromises population viability, reduces a species ability to respond to climate change, and ultimately may reduce biodiversity. We studied the current state and potential causes of fragmentation in grizzly bears over approximately 1,000,000 km 2 of western Canada, the northern United States (US), and southeast Alaska. We compiled much of our data from projects undertaken with a variety of research objectives including population estimation and trend, landscape fragmentation, habitat selection, vital rates, and response to human development. Our primary analytical techniques stemmed from genetic analysis of 3,134 bears, supplemented with radiotelemetry data from 792 bears. We used 15 locus microsatellite data coupled withmeasures of genetic distance, isolation-by-distance (IBD) analysis, analysis of covariance (ANCOVA), linear multiple regression, multi-factorial correspondence analysis (to identify population divisions or fractures with no a priori assumption of group membership), and population-assignment methods to detect individual migrants between immediately adjacent areas. These data corroborated observations of inter-area movements from our telemetry database. In northern areas, we found a spatial genetic pattern of IBD, although there was evidence of natural fragmentation from the rugged heavily glaciated coast mountains of British Columbia (BC) and the Yukon. These results contrasted with the spatial pattern of fragmentation in more southern parts of their distribution. Near the Canada-US border area, we found extensive fragmentation that corresponded to settled mountain valleys andmajor highways. Genetic distances across developed valleys were elevated relative to those across undeveloped valleys in central and northern BC. In disturbed areas, most inter-area movements detected were made by male bears, with few female migrants identified. North-south movements within mountain ranges (Mts) and across BC Highway 3 were more common than east-west movements across settled mountain valleys separating Mts. Our results suggest that relatively distinct subpopulations exist in this region, including the Cabinet, Selkirk South, and the decadesisolated Yellowstone populations. Current movement rates do not appear sufficient to consider the subpopulations we identify along the Canada-US border as 1 inter-breeding unit. Although we detected enough male movement to mediate gene flow, the current low rate of female movement detected among areas is insufficient to provide a demographic rescue effect between areas in the immediate future (0-15 yr). In Alberta, we found fragmentation corresponded to major east-west highways (Highways 3, 11, 16, and 43) and most inter-area movements were made by males. Gene flow and movement rates between Alberta and BC were highest across the Continental Divide south of Highway 1 and north of Highway 16. In the central region between Highways 1 and 11, we found evidence of natural fragmentation associated with the extensive glaciers and icefields along the Continental Divide. The discontinuities that we identified would form appropriate boundaries formanagement units. We related sex-specific movement rates between adjacent areas to several metrics of human use (highway traffic, settlement, and humancaused mortality) to understand the causes of fragmentation. This analysis used data from 1,508 bears sampled over a 161,500-km 2 area in southeastern BC, western Alberta, northern Idaho, and northern Montana during 1979-2007. This area was bisected by numerous human transportation and settlement corridors of varying intensity and complexity. We used multiple linear regression and ANCOVA to document the responses of female and male bears to disturbance. Males and females both demonstrated reduced movement rates with increasing settlement and traffic. However, females reduced their movement rates dramatically when settlement increased to >20% of the fracture zone. At this same

Wildlife Monographs↗

USGS2024

Preparing for a Bsal invasion into North America has improved multi-sector readiness

Western palearctic salamander susceptibility to the skin disease caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal) was recognized in 2014, eliciting concerns for a potential novel wave of amphibian declines following the B. dendrobatidis (Bd) chytridiomycosis global pandemic. Although Bsal had not been detected in North America, initial experimental trials supported the heightened susceptibility of caudate amphibians to Bsal chytridiomycosis, recognizing the critical threat this pathogen poses to the North American salamander biodiversity hotspot. Here, we take stock of 10 years of research, collaboration, engagement, and outreach by the North American Bsal Task Force. We summarize main knowledge and conservation actions to both forestall and respond to Bsal invasion into North America. We address the questions: what have we learned; what are current challenges; and are we ready for a more effective reaction to Bsal’s eventual detection? We expect that the many contributions to preemptive planning accrued over the past decade will pay dividends in amphibian conservation effectiveness and can inform future responses to other novel wildlife diseases and extreme threats.

North America↗

USGS1994

Conservation of North Pacific shorebirds

In his introduction to the 1979 Symposium proceedings entitled “Shorebirds in Marine Environments," Frank Pitelka stressed the need for studies and conservation programs that spanned the western hemisphere (Pitelka 1979). In the 15 years since Pitelka's call to arms, the locations of many important migratory and wintering sites for shorebirds have been identified in the Americas (Senner and Howe 1984, Morrison and Ross 1989, Morrison and Butler 1994) and in the East Asian-Australasian flyway (Lane and Parish 1991, Mundkur 1993, Watkins 1993). However, assessments for Central America, the Russian Far East and most of Oceania remain incomplete or lacking. The recognition that shorebird conservation required the protection of habitats throughout the birds' range (e.g., Morrison 1984, Davidson and Evans 1989 in Ens et al. 1990) prompted the establishment of the Western Hemisphere Shorebird Reserve Network (WHSRN) in the Americas in 1985 (Joyce 1986). This program complemented the 1971 Convention on Wetlands of International Importance Especially for Waterbirds (Ramsar Convention, Smart 1987), recognized by more that 50 countries world-wide. Our purpose for writing this paper is to: (1) describe the distribution of North Pacific shorebirds throughout their annual cycle; (2) review the locations of and threats to important sites used by North Pacific shorebirds during the breeding, migration, and wintering periods, and (3) outline a program for international conservation of Pacific shorebirds.

Transactions of the North American Wildlife and Na↗

USGS2020

Gaps and hotspots in the state of knowledge of pinyon-juniper communities

Pinyon-juniper (PJ) plant communities cover a large area across North America and provide critical habitat for wildlife, biodiversity and ecosystem functions, and rich cultural resources. These communities occur across a variety of environmental gradients, disturbance regimes, structural conditions and species compositions, including three species of juniper and two species of pinyon. PJ communities have experienced substantial changes in recent decades and identifying appropriate management strategies for these diverse communities is a growing challenge. Here, we surveyed the literature and compiled 441 studies to characterize patterns in research on PJ communities through time, across geographic space and climatic conditions, and among focal species. We evaluate the state of knowledge for three focal topics: 1) historical stand dynamics and responses to disturbance, 2) land management actions and their effects, and 3) potential future responses to changing climate. We identified large and potentially important gaps in our understanding of pinyon-juniper communities both geographically and topically. The effect of drought on Pinus edulis, the pinyon pine species in eastern PJ communities was frequently addressed, while few studies focused on drought effects on Pinus monophylla , which occurs in western PJ communities. The largest proportion of studies that examined land management actions only measured their effects for one year. Grazing was a common land-use across the geographic range of PJ communities yet was rarely studied. We found only 39 studies that had information on the impacts of anthropogenic climate change and most were concentrated on Pinus edulis . These results provide a synthetic perspective on PJ communities that can help natural resource managers identify relevant knowledge needed for decision-making and researchers design new studies to fill important knowledge gaps.

Arizona, California, Colorado, Nevada, New Mexico,↗

USGS2010

Health evaluation of western arctic King Eiders ( Somateria spectabilis )

The western arctic population of King Eiders ( Somateria spectabilis ) has declined by >50% in recent years. A health assessment was conducted for adult King Eiders breeding on the north slope of Alaska, USA, to evaluate body condition ( n =90, 2002–2006) and baseline biochemical and hematologic values ( n =20–30, 2005–2006). Body condition for males and females was excellent. Total protein, calcium, alkaline phosphatase, amylase, and globulin were significantly higher in females than in males, likely because of differences in reproductive physiology. These baseline health data can be used to promote conservation of King Eiders and other closely related species of concern.

Journal of Wildlife Diseases↗

USGS2011

Non-native species impacts on pond occupancy by an anuran

Non‐native fish and bullfrogs ( Lithobates catesbeianus ) are frequently cited as contributing to the decline of ranid frogs in the western United States, so we hypothesized that non‐native species, habitat, or a combination of these relate to the probability of local extinction for northern red‐legged frogs ( Rana aurora ) in Oregon, USA. We also hypothesized that the probability of colonization relates to land use, wetland size, or riparian forest. In a 5‐yr study, we found no support for an effect of non‐native species on northern red‐legged frogs. Instead, probability of local extinction decreased with the extent of emergent vegetation and riparian forest. This finding suggests that managers consider the role of habitat when confronting non‐native species problems.

Oregon↗

USGS2011

Hydrogeology and simulation of groundwater flow in the Arbuckle-Simpson aquifer, south-central Oklahoma

The Arbuckle-Simpson aquifer in south-central Oklahoma provides water for public supply, farms, mining, wildlife conservation, recreation, and the scenic beauty of springs, streams, and waterfalls. Proposed development of water supplies from the aquifer led to concerns that large-scale withdrawals of water would cause decreased flow in rivers and springs, which in turn could result in the loss of water supplies, recreational opportunities, and aquatic habitat. The Oklahoma Water Resources Board, in collaboration with the Bureau of Reclamation, the U.S. Geological Survey, Oklahoma State University, and the University of Oklahoma, studied the aquifer to provide the Oklahoma Water Resources Board the scientific information needed to determine the volume of water that could be withdrawn while protecting springs and streams. The U.S. Geological Survey, in coopertion with the Oklahoma Water Resources Board, did a study to describe the hydrogeology and simulation of groundwater flow of the aquifer. The outcrop of the Arbuckle-Simpson aquifer covers an area of about 520 square miles in Carter, Coal, Johnston, Murray, and Pontotoc Counties. Three subdivisions of the aquifer outcrop were designated for this study: the eastern, central, and western Arbuckle-Simpson aquifer. This study emphasized the eastern Arbuckle-Simpson aquifer because it is the largest part of the aquifer by area and volume; most groundwater withdrawals are from the eastern Arbuckle-Simpson aquifer; and the largest (by flow) streams and springs sourced from the aquifer are on the eastern Arbuckle-Simpson aquifer. The aquifer lies in an uplifted area commonly referred to as the Arbuckle Mountains, which is characterized by great thicknesses of mostly carbonate rocks, uplifts, folded structures, and large fault displacements. The Arbuckle-Simpson aquifer is contained in three major rock units of Late Cambrian to Middle Ordovician age: the Timbered Hills, Arbuckle, and Simpson Groups. The aquifer is underlain by low-permeability Cambrian and Proterozoic igneous and metamorphic rocks, and is confined above by younger sedimentary rocks of various ages in areas where the top of the aquifer dips below the surface. The major part of the Arbuckle-Simpson aquifer is the Arbuckle Group, which consists of as much as 6,700 feet of limestone in the western Arbuckle-Simpson aquifer, but which thins to an estimated 3,000 feet of predominantly dolostone in the eastern Arbuckle-Simpson aquifer. Water is obtained from cavities, solution channels, fractures, and intercrystalline porosity in the limestone and dolostone. The overlying Simpson Group, consisting of sandstones, shales, and limestones, is as much as 2,300 feet thick in the western Arbuckle-Simpson aquifer, but generally is less than 1,000 feet thick in the eastern aquifer. Water in the Simpson Group is stored primarily in pore spaces between the sand grains in the sandstones. A digital, three-dimensional geologic framework model was constructed to define the geometric relations of fault blocks and subsurface rock units across complex fault zones of the eastern Arbuckle-Simpson aquifer. Geologic data for the model were obtained from 126 drill holes; stratigraphic contacts and faults defined from a digitized version of the surface geologic map; and fault geometry, stratigraphic thickness, and information compiled from geologic and hydrogeologic reports and maps. Groundwater in the aquifer moves from areas of high head (altitude) to areas of low head along streams and springs. The potentiometric surface in the eastern Arbuckle-Simpson aquifer generally slopes from a topographic high from northwest to the southeast, indicating that regional groundwater flow is predominantly toward the southeast. Freshwater is known to extend beyond the aquifer outcrop near the City of Sulphur, Oklahoma, and Chickasaw National Recreation Area, where groundwater flows west from the outcrop of the eastern Arbuckle-Simpson aquifer and becomes confin

Scientific Investigations Report↗

USGS1993

Economic analysis of critical habitat designation for the desert tortoise (Mojave population)

The U.S. Fish and Wildlife Service emergency 1isted the Mojave population of the desert tortoise as endangered on August 4, 1989. The Mojave population formally was listed as threatened on April 2, 1990. The Endangered Species Act of 1973, as amended, requires that the economic benefits and costs and other relevant effects of critical habitat designation be considered. The Secretary of the Interior may exclude from designation areas where the costs of designation are greater than the benefits, unless the exclusion would result in extinction of the species. Desert tortoises are threatened by an accumulation of human-and disease-related mortality accompanied by habitat destruction, degradation, and fragmentation. Many desert tortoises are illegally collected for pets, food, and commercial trade. Others are accidentally struck and killed by vehicles on roads and highways or are killed by gunshot or vehicles traveling off-highway. Raven predation on hatchling desert tortoises has increased as raven populations in the desert have risen. An upper respiratory tract disease is suspected to be a major cause of mortality in the western Mojave Desert. This presumably incurable affliction presumably is thought to be spread through the release of infected tortoises into the desert. The Service has proposed designating critical habitat in nine counties within four states. The 12 critical habitat units encompass 6.4 million acres of land, more than 80% federally owned. This region is economically and demographically diverse. Most of the land is sparsely settled and characterized as a hot desert ecosystem. Major industries in the region include entertainment and lodging (primarily in Las Vegas), property development to accommodate the rapid population growth, and services. Millions of rural acres in the region are leased by the federal government for livestock grazing and used for mining. Overall economic benefits to the affected states derived from cattle and sheep grazing in the hot desert areas are minimal and, according to a recent U.S. General Accounting Office study (1991), local economies do not depend on the grazing of public lands for economic survival. The economic analysis describes the economy in 1990, prior to designation, and estimates the effects of designation. The report estimates those incremental effects attributable to critical habitat designation. Impacts attributable to listing the species were not considered in this analysis. Although critical habitat units have been designated in nine counties, two counties are omitted from the economic analysis because of the small proportion of critical habitat acreage they include. Three key activities (cattle grazing, mineral extraction, and off-road vehicle use) were studied in detail. Even if livestock grazing and commercial off-road racing events were eliminated in the proposed critical habitat units, the potential incremental regional economic impacts would be extremely small. The findings in the report do not include the assumption that mining would be eliminated from critical habitat units, but rather that consultation may result in added mitigation and/or relocation of features. Studies show that society will realize benefits from preservation of species and ecosystems. Survey-based studies confirm that benefits exist and are substantial in size, although these benefits often are not measured in traditional economic markets. The total benefit to society of desert tortoise preservation includes several components. Biodiversity in the Mojave and Colorado Deserts will be improved, some recreation values may increase, and gains in intrinsic value will be realized. Critical habitat designation should result in the loss of fewer than 425 total jobs in the seven counties. These include 340 direct ranching jobs and 85 indirect jobs in other industries. This estimated employment loss will not be permanent for most laborers, it is anticipated that over 85% will be reemployed within two years. The economic consequences of designating critical habitat includes reduced ranch profits in the seven counties of $4,470,000 [the estimated permanent decrease in ranch profits, capitalized at 10% for a 50-year period, in accordance with the methodology of River, et al. (1978)]. Second, the federal government will compensate allottees with a one-time payment estimated at $376,000 for the loss of permanent improvements to grazing lands (pending BLM administrative decisions of partially affected allotments). Finally, discontinuing grazing fees will result in an annual reduction of $170,000 in collected grazing fees that are divided among range improvements, the Federal Treasury, and local governments.

California, Nevada↗

USGS1984

Avian cholera in Nebraska's Rainwater Basin

The first report of avian cholera in North America occurred in northwestern Texas in winter 1944 (Quortrup et al. 1946). In 1975, mortality from avian cholera occurred for the first time in waterfowl in the Rainwater Basin of Nebraska when an estimated 25,000 birds died (Zinkl et al. 1977). Avian cholera has continued to cause mortality in wild birds in specific areas of the Basin each spring since. Losses of waterfowl from avian cholera continue to be much greater in some of the wetlands in the western part of the Basin than in the east. Several wetlands in the west have consistently higher mortality and are most often the wetlands where initial mortality is noticed each spring (Figure 1). The establishment of this disease in Nebraska is of considerable concern because of the importance of the Rainwater Basin as a spring staging area for waterfowl migrating to their breeding grounds. The wetlands in this area are on a major migration route used by an estimated 5 to 9 million ducks and several hundred thousand geese. A large portion of the western mid-continental greater white-fronted goose (Anser albifrons) population stage in the Basin each spring. Occasionally, whooping cranes (Grus americana) use these wetlands during migration, and lesser sandhill cranes (Grus canadensis) staging on the nearby Platte River sometimes use wetlands where avian cholera occurs (Anonymous 1981). Our objectives were to determine whether certain water quality variables in the Rainwater Basin differed between areas of high and low avian cholera incidence. These results would then be used for laboratory studies involving the survivability of Pasteurella multocida, the causative bacterium of avian cholera. Those studies will be reported elsewhere.

Nebraska↗

USGS2013

On the role of budget sufficiency, cost efficiency, and uncertainty in species management

Many conservation planning frameworks rely on the assumption that one should prioritize locations for management actions based on the highest predicted conservation value (i.e., abundance, occupancy). This strategy may underperform relative to the expected outcome if one is working with a limited budget or the predicted responses are uncertain. Yet, cost and tolerance to uncertainty rarely become part of species management plans. We used field data and predictive models to simulate a decision problem involving western burrowing owls (Athene cunicularia hypugaea) using prairie dog colonies (Cynomys ludovicianus) in western Nebraska. We considered 2 species management strategies: one maximized abundance and the other maximized abundance in a cost-efficient way. We then used heuristic decision algorithms to compare the 2 strategies in terms of how well they met a hypothetical conservation objective. Finally, we performed an info-gap decision analysis to determine how these strategies performed under different budget constraints and uncertainty about owl response. Our results suggested that when budgets were sufficient to manage all sites, the maximizing strategy was optimal and suggested investing more in expensive actions. This pattern persisted for restricted budgets up to approximately 50% of the sufficient budget. Below this budget, the cost-efficient strategy was optimal and suggested investing in cheaper actions. When uncertainty in the expected responses was introduced, the strategy that maximized abundance remained robust under a sufficient budget. Reducing the budget induced a slight trade-off between expected performance and robustness, which suggested that the most robust strategy depended both on one's budget and tolerance to uncertainty. Our results suggest that wildlife managers should explicitly account for budget limitations and be realistic about their expected levels of performance.

Nebraska↗

USGS2004

Tertiary thrust systems and fluid flow beneath the Beaufort coastal plain (1002 area), Arctic National Wildlife Refuge, Alaska, U.S.A.

Beneath the Arctic coastal plain (commonly referred to as "the 1002 area") in the Arctic National Wildlife Refuge, northeastern Alaska, United States, seismic reflection data show that the northernmost and youngest part of the Brookian orogen is preserved as a Paleogene to Neogene system of blind and buried thrust-related structures. These structures involve Proterozoic to Miocene (and younger?) rocks that contain several potential petroleum reservoir facies. Thermal maturity data indicate that the deformed rocks are mature to overmature with respect to hydrocarbon generation. Oil seeps and stains in outcrops and shows in nearby wells indicate that oil has migrated through the region; geochemical studies have identified three potential petroleum systems. Hydrocarbons that were generated from Mesozoic source rocks in the deformed belt were apparently expelled and migrated northward in the Paleogene, before much of the deformation in this part of the orogen. It is also possible that Neogene petroleum, which was generated in Tertiary rocks offshore in the Arctic Ocean, migrated southward into Neogene structural traps at the thrust front. However, the hydrocarbon resource potential of this largely unexplored region of Alaska's North Slope remains poorly known. In the western part of the 1002 area, the dominant style of thin-skinned thrusting is that of a passive-roof duplex, bounded below by a detachment (floor thrust) near the base of Lower Cretaceous and younger foreland basin deposits and bounded above by a north-dipping roof thrust near the base of the Eocene. East-west-trending, basement-involved thrusts produced the Sadlerochit Mountains to the south, and buried, basement-involved thrusts are also present north of the Sadlerochit Mountains, where they appear to feed displacement into the thin-skinned system. Locally, late basement-involved thrusts postdate the thin-skinned thrusting. Both the basement-involved thrusts and the thin-skinned passive-roof duplex were principally active in the Miocene. In the eastern part of the 1002 area, a northward-younging pattern of thin-skinned deformation is apparent. Converging patterns of Paleocene reflectors on the north flank of the Sabbath syncline indicate that the Aichilik high and the Sabbath syncline formed as a passive-roof duplex and piggyback basin, respectively, just behind the Paleocene deformation front. During the Eocene and possibly the Oligocene, thin-skinned thrusting advanced northward over the present location of the Niguanak high. A passive-roof duplex occupied the frontal part of this system. The Kingak and Hue shales exposed above the Niguanak high were transported into their present structural position during the Eocene to Oligocene motion on the long thrust ramps above the present south flank of the Niguanak high. Broad, basement-cored subsurface domes (Niguanak high and Aurora dome) formed near the deformation front in the Oligocene, deforming the overlying thin-skinned structures and feeding a new increment of displacement into thin-skinned structures directly to the north. Deformation continued through the Miocene above a detachment in the basement. Offshore seismicity and Holocene shortening documented by previous workers may indicate that contractional deformation continues to the present day.

Alaska↗

USGS2009

Plasma biochemistry values in emperor geese (Chen canagica) in Alaska: Comparisons among age, sex, incubation, and molt

Reduced populations of emperor geese ( Chen canagica ), a Bering Sea endemic, provided the need to assess plasma biochemistry values as indicators of population health. A precursory step to such an investigation was to evaluate patterns of variability in plasma biochemistry values among age, sex, and reproductive period. Plasma from 63 emperor geese was collected on their breeding grounds on the Yukon-Kuskokwim Delta in western Alaska, USA. The geese sampled included 18 incubating adult females captured, in mid June, on their nests by using bow nets, and 30 adults and 15 goslings captured in corral traps in late July and early August, when the adults were molting their wing feathers and the goslings were 5–6 weeks old. Plasma was evaluated for 15 biochemical parameters, by comparing results among age, sex, and sampling period (incubation versus wing-feather molt). Ten of the 15 biochemical parameters assayed differed among adults during incubation, the adults during molt, and the goslings at molt, whereas sex differences were noted in few parameters.

Alaska↗

USGS1986

The Breeding Bird Survey: Its first fifteen years, 1965-1979

The Breeding Bird Survey (BBS) is an ongoing cooperative program sponsored jointly by the U.S. Fish and Wildife Service and the Canadian Wildlife Service. Its main purpose is to estimate population trends of the many species of birds that nest in North America north of Mexico and that migrate across international boundaries. This survey provides information, both locally by ecological or political regions and on a continental scale, on (1) short-term population changes that can be correlated with specific weather incidents, (2) recovery periods following catastrophic declines, (3) normal year-to-year variations, (4) long-term population trends, and (5) invasions of exotics. The BBS also permits detailed computer mapping of relative abundance of each species, either year by year to show changes in distribution and relative abundance, or the average over a period of years. It provides base-line data with which more intensive local studies can be compared. For biogeographic studies it provides uniform sampling of bird populations by major physiographic regions across the continent. In conjunction with the Audubon Christmas Bird Count, it permits comparison of summer and winter distribution of species that winter in the United States. Most species of North American birds migrate across international boundaries, especially those shared with Canada, Mexico, and the Soviet Union. As part of our responsibility under treaties with these nations, the U.S. Fish and Wildlife Service has developed the BBS to monitor avian population changes so that any adverse trends can be detected early. This provides the opportunity to determine the reasons for any increase or decrease, to define geographic areas in which changes are greatest, to study correlations between avian population changes and land-use changes, and to make recommendations for controlling undesirable bird population trends. For example, the BBS can be used to detect and estimate the extent of losses resulting from widespread use of pesticides, and to reveal whether major population changes of a given species (e.g., Dickcissel) in certain States are related to a continental decline or are merely a result of population shifts within the breeding range. Effects of urban and suburban expansion are often reflected in the loss of forest interior birds. Population trends for 230 species as well as several avian genera and families are discussed and graphed in this report. For most of these species, regional and well as continental trends are shown. The three major regions discussed are the Eastern, Central, and Western, bounded by the Mississippi River and the eastern base of the Rocky Mountains. Additional graphs for certain States or physiographic regions are included for selected species of special interest. The following paragraphs summarize general trends in the major bird families. The native herons in general are maintaining their populations, whereas the exotic Cattle Egret continues its geographic spread and its steady increase. Waterfowl as a group are stable or increasing. Although most widespread species of hawks are on the increase, the rarer species show evidence of decline. Among the gallinaceous birds, the greatest change was a sharp drop in Northern Bobwhite as a result of the exceptionally cold winters of 1976-77 and 1977-78 in the Ohio Valley and the Middle Atlantic States. Killdeer populations, except for a minor decline during these two winters, showed strong increases except in the West. American Woodcock were poorly sampled by the BBS because they were relatively inactive during daylight. Common Snipe and the other common shorebirds that nest in the United States and southern Canada exhibited stable or increasing populations, especially in the Eastern and Central regions. Herring Gull counts varied dramatically and irregularly from year to year. Laughing Gulls increased along the Atlantic coast and Franklin's Gulls declined in the interior of the continen

Resource Publication↗

USGS2010

Influence of roads, rivers, and mountains on natal dispersal of white-tailed deer

Natural and anthropogenic landscape features, such as rivers, mountain ranges, and roads can alter animal dispersal paths and movement patterns. Consequently landscape, through its effects on dispersal, may influence many ecological processes, including disease transmission, invasion dynamics, and gene flow. To investigate influences of landscape features on dispersal patterns of a large mammal, we captured and radiomarked 363 juvenile male white-tailed deer (Odocoileus virginianus), including 212 confirmed dispersers, in 2 topographically dissimilar study areas in Pennsylvania, USA. Dispersal azimuths were uniformly distributed in the western study area (WSA), where there was irregular, hilly topography. Mean dispersal azimuths paralleled ridge direction in the eastern study area, where long parallel ridges were aligned northeastsouthwest. Major roads in both areas and a large river in the WSA were semipermeable barriers to dispersal of juvenile males; dispersal paths were less likely to intersect these linear features. Dispersal movements were direct and brief, typically lasting <12 hours. For all dispersers, we found no evidence for preference or avoidance of establishing adult, postdispersal ranges in proximity to roads; however, deer that encountered roads near the terminus of their dispersal path were more likely to stop on the near side. Further, for deer that established postdispersal home ranges near major roads, these features influenced range placement such that locations were typically clustered on one side of the road. The influence of roads, rivers, and mountains on dispersal paths and postdispersal locations of white-tailed deer suggest that landscape-specific features should be considered in conservation and management of this and possibly other species of large mammals. ?? 2010 The Wildlife Society.

Journal of Wildlife Management↗

USGS1978

Hydrologic reconnaissance of the Fish Springs Flat area, Tooele, Juab and Millard counties, Utah

The Fish Springs Flat area includes about 590 square miles (1,530 square kilometers) in western Utah. Total annual precipitation on the area averages about 7 inches (180 millimeters) and totals about 232,000 acre-feet (286 cubic hectometers). Fish Springs Wash is the major drainage in the area; and, along with numerous smaller washes, it flows only in direct response to precipitation. Runoff from the area is estimated to be about 2,000 acre-feet (2.5 cubic hectometers) per year. The estimated amount of water recoverable from storage in the upper 100 feet (30 meters) of saturated valley fill is about 550,000 acre-feet (680 cubic hectometers), and most of this water is slightly to moderately saline. The water in the Fish Springs Flat area ranges from slightly saline to briny, and the predominant ions in the water are sodium and chloride. The water that underlies the mudflats in the northwest part of the area is briny. Water that issues from Fish Springs is slightly saline. The water in the Fish Springs Flat area is not suitable for drinking. The water that issues from Fish Springs is used for wildlife management, which includes ponding and irrigation of vegetation (chiefly saltgrass) in the Fish Springs National Wildlife Refuge. The water from the wells in the area is used for livestock and mining operations. Ground-water recharge from precipitation is about 4,000 acre-feet (5 cubic hectometers) annually. Ground-water discharge is chiefly by springs and evapotranspiration. The largest springs in the Fish Springs group discharge about 26,000 acre-feet (32 cubic hectometers) annually. All other springs discharge about 600 acre-feet (0.74 cubic hectometer) per year, or only about 2 percent of the total spring discharge. Discharge by evapotranspiration is about 8,000 acre-feet (10 cubic hectometers) per year. Discharge by wells and by subsurface outflow is negligible. The difference between discharge and local recharge--approximately 31,000 acre-feet (38 cubic hectometers)--is assumed to enter the Fish Springs Flat area by interbasin flow.

Utah↗

USGS2005

Calculation of area and volume for the south part of Great Salt Lake, Utah

The U.S. Geological Survey, in cooperation with the Utah Department of Natural Resources, Division of Wildlife Resources, collected bathymetric data for the south part of Great Salt Lake during 2002-04 using a single-beam, high-definition fathometer and real-time differential global positioning system. About 7.6 million depth measurements were collected along more than 930 miles (1,690 kilometers) of survey transects. Sound-velocity profiles were obtained in conjunction with the bathymetric data to provide time-of-travel corrections to the depth calculations. Data were processed with commercial hydrographic software and exported into geographic information system (GIS) software for mapping and calculation of area and volume. Area and volume calculations show a maximum area of about 508,000 acres (2,056 square kilometers) and a maximum volume of about 9,257,000 acre-feet (11.42 cubic kilometers) at a water-surface altitude of 4,200 feet (1,280 meters). Minimum water-surface altitude of the south part of Great Salt Lake is just below 4,167 feet (1,279 meters) in the area just south of the Union Pacific railroad causeway halfway between Promontory Point and the western edge of the lake. At this altitude, and continuing up to about 4,176 feet (1,279 meters), the south part of the lake is separated into two areas by a ridge extending from Promontory Point to Hat Island. Calculations for area and volume are based on a low altitude of 4,167 feet (1,279 meters) to a high altitude of 4,200 feet (1,280 meters).

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