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The responses of individual species to environmental changes can be manifested at multiple levels that range from individual-level (i.e., behavioral responses) to population-level (i.e., demographic) impacts. Major environmental changes that ultimately result in population level impacts are often first detected as individual-level responses. For example, herbivores respond to limited forage availability during drought periods by increasing the duration of foraging periods and expanding home range areas to compensate for the reduction in forage. However, if the individual-level responses are not sufficient to compensate for reduced forage availability, reduced survival and reproductive rates may result. We studied...
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This dataset consists of one table with sample collection locations and results of screening resident wildlife for Cryptosporidium and Giardia in the Alaskan Arctic, 2012-2017. We analyzed feces collected from polar bear, Pacific walrus, Arctic fox, and caribou with MERIFLUOR direct immunofluorescence assay to determine the presence of Cryptosporidium oocysts and Giardia cysts.
Understanding processes and mechanisms resulting in observed ecological patterns is critical information for biologists charged with effectively managing and conserving wildlife populations. In many areas across North America woodland caribou (Rangifer tarandus caribou Gmelin) populations are declining, as are caribou and reindeer populations globally. Why these declines are occurring is a key research question of biologists and managers. I investigated factors influencing recruitment of mountain-dwelling woodland caribou using long-term time series from ten herds (populations) in the Yukon Territory, Canada (Yukon). Recruitment was indexed by the calf:cow ratio observed during the fall breeding season using data...
Climate change is already affecting species in many ways. Because individual species respond to climate change differently, some will be adversely affected by climate change whereas others may benefit. Successfully managing species in a changing climate will require an understanding of which species will be most and least impacted by climate change. Although several approaches have been proposed for assessing the vulnerability of species to climate change, it is unclear whether these approaches are likely to produce similar results. In this study, we compared the relative vulnerabilities to climate change of 76 species of birds, mammals, amphibians, and trees based on three different approaches to assessing vulnerability....
In this dissertation I address the evolutionary history, ecogeographic variation, and phylogeography (single species and comparative) of collared pikas (Ochotona collaris ). Pikas are small (ca. 150 g) lagomorphs (order Lagomorpha: rabbits, hares, and pikas) found in alpine habitats throughout much of the Holarctic. Only two of the 30 extant pika species occur in the New World. The northern of the two species, O. collaris is separated 800 km north of the American pika (O. princeps ). In the first chapter, I employ recently developed molecular analytical techniques to examine when the two North American species diverged. This chapter sets the evolutionary context for the subsequent diversification within O. collaris....
Reproductive output was estimated for a cyclic population of snowshoe hares (Lepus americanus) in the Kluane Lake region of the southwest Yukon Territory. Data collected by five researchers were collated over 8 years (1989-1996). Pregnant hares were captured and held in cages until they gave birth so that reproductive characteristics could be measured. Pregnancy rate, litter size, and neonate size fluctuated significantly throughout the cycle, changes occurring about 2 years before corresponding changes in density. Pregnancy rates were nearly 100% early in the breeding season, but declined up to 20% in the last gestation periods of the year. The number of litters produced in a breeding season varied between two...
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Climate change is expected to worsen the harmful effects of invasive species on native wildlife. This presents a growing conservation challenge for invasive species managers in the southeastern United States where thousands of invasive species exist. While many of these invasive species currently have relatively small ranges in the southeastern U.S., climate change may allow them to expand into new regions. To effectively plan and respond to the redistribution of invasive species, it is crucial to coordinate existing information and identify future information needs across regional boundaries. The ultimate goal of this project is to improve invasive species management in the face of climate change by establishing...
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The GIS shapefile Extra limit counts of southern sea otters 2019 is a point layer representing the locations of sea otter sightings that fall outside the officially recognized range of the southern sea otter (Enhydra lutris nereis) in mainland California. These data were collected during the spring 2019 range-wide census. The USGS range-wide sea otter census has been undertaken each year since 1982, using consistent methodology involving both ground-based and aerial-based counts. The spring census provides the primary basis for gauging population trends by State and Federal management agencies. Sea otter distribution in California (the mainland range) is considered to comprise a band of potential habitat stretching...
map background search result map search result map Annual California Sea Otter Census: 2019 Extra Limit Observations Shapefile Cryptosporidium and Giardia Occurrence Data in Wildlife from Arctic Alaska, 2012-2017 Southeast Regional Invasive Species and Climate Change Management Network (SE RISCC) Annual California Sea Otter Census: 2019 Extra Limit Observations Shapefile Cryptosporidium and Giardia Occurrence Data in Wildlife from Arctic Alaska, 2012-2017 Southeast Regional Invasive Species and Climate Change Management Network (SE RISCC)