Wilson R.R.,The Wilderness Society |
Prichard A.K.,Inc. Environmental Research and Services |
Parrett L.S.,Alaska Department of Fish and Game |
Carroll G.M.,Alaska Department of Fish and Game |
And 3 more authors.
PLoS ONE | Year: 2012
Many caribou (Rangifer tarandus) populations are declining worldwide in part due to disturbance from human development. Prior to human development, important areas of habitat should be identified to help managers minimize adverse effects. Resource selection functions can help identify these areas by providing a link between space use and landscape attributes. We estimated resource selection during five summer periods at two spatial scales for the Teshekpuk Caribou Herd in northern Alaska prior to industrial development to identify areas of high predicted use for the herd. Additionally, given the strong influence parturition and insect harassment have on space use, we determined how selection differed between parturient and non-parturient females, and between periods with and without insect harassment. We used location data acquired between 2004-2010 for 41 female caribou to estimate resource selection functions. Patterns of selection varied through summer but caribou consistently avoided patches of flooded vegetation and selected areas with a high density of sedge-grass meadow. Predicted use by parturient females during calving was almost entirely restricted to the area surrounding Teshekpuk Lake presumably due to high concentration of sedge-grass meadows, whereas selection for this area by non-parturient females was less strong. When insect harassment was low, caribou primarily selected the areas around Teshekpuk Lake but when it was high, caribou used areas having climates where insect abundance would be lower (i.e., coastal margins, gravel bars). Areas with a high probability of use were predominately restricted to the area surrounding Teshekpuk Lake except during late summer when high use areas were less aggregated because of more general patterns of resource selection. Planning is currently underway for establishing where oil and gas development can occur in the herd's range, so our results provide land managers with information that can help predict and minimize impacts of development on the herd.
White K.S.,Alaska Department of Fish and Game |
Pendleton G.W.,Alaska Department of Fish and Game |
Crowley D.,Alaska Department of Fish and Game |
Griese H.J.,673 CES CEANC |
And 6 more authors.
Journal of Wildlife Management | Year: 2011
Ecological theory predicts that individual survival should vary between sex and age categories due to differences in allocation of nutritional resources for growth and reproductive activities. During periods of environmental stress, such relationships may be exacerbated, and affect sex and age classes differently. We evaluated support for hypotheses about the relative roles of sex, age, and winter and summer climate on the probability of mountain goat (Oreamnos americanus) survival in coastal Alaska. Specifically, we used known-fates analyses (Program MARK) to model the effects of age, sex, and climatic variation on survival using data collected from 279 radio-marked mountain goats (118 M, 161 F) in 9 separate study areas during 1977-2008. Models including age, sex, winter snowfall, and average daily summer temperature (during Jul-Aug) best explained variation in survival probability of mountain goats. Specifically, our findings revealed that old animals (9+ yr) have lower survival than younger animals. In addition, males tended to have lower survival than females, though differences only existed among prime-aged adult (5-8 yr) and old (9+ yr) age classes. Winter climate exerted the strongest effects on mountain goat survival; summer climate, however, was significant and principally influenced survival during the following winter via indirect effects. Furthermore, old animals were more sensitive to the effects of winter conditions than young or prime-aged animals. These findings detail how climate interacts with sex and age characteristics to affect mountain goat survival. Critically, we provide baseline survival rate statistics across various age, sex, and climate scenarios. These data will assist conservation and management of mountain goats by enabling detailed, model-based demographic forecasting of human and/or climate-based population impacts. © The Wildlife Society, 2011.
Smith M.A.,Audubon Alaska |
Walker N.J.,Audubon Alaska |
Free C.M.,Audubon Alaska |
Free C.M.,Rutgers University |
And 4 more authors.
Biological Conservation | Year: 2014
Effective marine bird conservation requires identification of at-sea locations used by populations for foraging, staging, and migration. Using an extensive database of at-sea survey data spanning over 30. years, we developed a standardized and data-driven spatial method for identifying globally significant marine Important Bird Areas in Alaska. To delineate these areas we developed a six-step process: binning data and accounting for unequal survey effort, filtering input data for persistence of species use, using a moving window analysis to produce maps representing a gradient from low to high abundance, drawing core area boundaries around major concentrations based on abundance thresholds, validating the results, and combining overlapping boundaries into important areas for multiple species. We identified 126 bird core areas which were merged into 59 pelagic sites important to 45 out of 57 species assessed. The final areas included approximately 34-38% of all marine birds in Alaska waters, within just 6% of the total area. We identified globally significant Important Bird Areas spanning 20 degrees of latitude and 56 degrees of longitude, in two different oceans, with climates ranging from temperate to polar. Although our maps did suffer from some data gaps, these gaps did not preclude us from identifying sites that incorporated 13% of the assessed continental waterbird population and 9% of the assessed global seabird population. The application of this technique over a large and productive region worked well for a wide range of birds, exhibiting a variety of foraging strategies and occupying a variety of ecosystem types. © 2014 Elsevier Ltd.
Warnock N.,Audubon Alaska
Journal of Avian Biology | Year: 2010
Places where migrant birds stop to rest, drink, and eat at are often described as either stopover or staging sites. Attempts have been made to differentiate between these two terms but they are frequently used interchangeably. Some authors have equated staging sites with sites that attract large concentrations (many thousands) of birds, a definition that others have expanded to include long stopover durations and significant rates of refueling on predictable, abundant prey. It has also been suggested that birds using staging sites are those that employ a jumping strategy during migration. I argue that while all sites where birds rest and feed during migration are stopover sites, further classification of stopover sites is of ecological and conservation value. I propose that sites with abundant, predictable food resources where birds prepare for an energetic challenge (usually a long flight over a barrier such as an ocean or a desert) requiring substantial fuel stores and physiological changes without which significant fitness costs are incurred are most appropriately described as staging sites. © 2010 The Authors.
Kirchhoff M.D.,Audubon Alaska
Marine Ornithology | Year: 2011
I reviewed methods and results of selected nearshore surveys conducted in Alaska over the past 30 years to identify common challenges and to suggest ways for improving the precision and accuracy of monitoring populations of Kittlitz's Murrelet Brachyramphus brevirostris. Boat-based surveys for Kittlitz's Murrelet are especially challenging because this relatively rare species is difficult to detect and identify at a distance and has a clumped or contagious distribution. This review suggests a number of changes in the design and conduct of surveys that could yield improved precision and accuracy. These include (1) increasing the proportion of survey effort in offshore waters, (2) orienting transects to sample across the nearshore density gradient, (3) using distance sampling methods to account for variable detection probabilities, (4) sampling over larger geographic areas and at multiple times during the summer, (5) improving species identification rates, and (6) using a "snapshot" count to enumerate flying birds. It is important to repeat the same survey design and protocol in a given survey area over time, but, depending on site-specific attributes such as bird numbers and distribution, physical environment and available resources to conduct surveys, no single approach will be optimal for all areas.
Miller S.D.,National Wildlife Federation |
Schoen J.W.,Audubon Alaska |
Faro J.,P.O. Box 2151 |
Klein D.R.,University of Alaska Fairbanks
Journal of Wildlife Management | Year: 2011
Hunting regulations for grizzly bears (Ursus arctos) in much of Alaska since 1980 increasingly were designed to reduce bear abundance in the expectation such regulations would lead to increased harvests by hunters of moose (Alces alces) and caribou (Rangifer tarandus). Regulations were liberalized during 1980-2010 primarily in the area we termed the Liberal Grizzly Bear Hunting Area (hereafter Liberal Hunt Area) which encompassed 76.2% of Alaska. By 2010, these changes resulted in longer hunting seasons (100% of Liberal Hunt Area had seasons > 100 days, 99.7% > 200 days, and 67.8% > 300 days), more liberal bag limits (99.1% of the Liberal Hunt Area with a bag limit ≥ 1/yr and 10.1% with a bag limit ≥ 2/yr), and widespread waiver of resident tag fees (waived in 95.7% of the Liberal Hunt Area). During 1995-2010, there were 124 changes that made grizzly bear hunting regulations more liberal and two making them more conservative. The 4-year mean for grizzly bear kills by hunters increased 213% between 1976-1980 (387 grizzly bears) and 2005-2008 (823 grizzly bears). Since 2000, long-term research studies on grizzly populations in the Liberal Hunt Area have been terminated without replacement. Management of large predators by the State of Alaska is constrained by a 1994 state statute mandating "intensive management" in areas classified as important for human consumptive use of ungulates. Current grizzly bear management in the Liberal Hunt Area is inconsistent with the recommendations of the National Research Council's 1997 report on predator management in Alaska. Current attitudes, policies and absence of science-based management of grizzly bears in Alaska are increasingly similar to those that resulted in the near extirpation of grizzly bears south of Canada in the 19th and 20th centuries. If current trends continue, they increase risks to portions of the largest and most intact population of grizzly bears in North America. Copyright © 2011 The Wildlife Society.
Franks S.E.,Simon Fraser University |
Norris D.R.,University of Guelph |
Kyser T.K.,Queen's University |
Fernandez G.,National Autonomous University of Mexico |
And 18 more authors.
Journal of Avian Biology | Year: 2012
Understanding the population dynamics of migratory animals and predicting the consequences of environmental change requires knowing how populations are spatially connected between different periods of the annual cycle. We used stable isotopes to examine patterns of migratory connectivity across the range of the western sandpiper Calidris mauri. First, we developed a winter isotope basemap from stable-hydrogen (δD), -carbon (δ 13C), and -nitrogen (δ 15N) isotopes of feathers grown in wintering areas. δD and δ 15N values from wintering individuals varied with the latitude and longitude of capture location, while δ 13C varied with longitude only. We then tested the ability of the basemap to assign known-origin individuals. Sixty percent of wintering individuals were correctly assigned to their region of origin out of seven possible regions. Finally, we estimated the winter origins of breeding and migrant individuals and compared the resulting empirical distribution against the distribution that would be expected based on patterns of winter relative abundance. For breeding birds, the distribution of winter origins differed from expected only among males in the Yukon-Kuskokwim (Y-K) Delta and Nome, Alaska. Males in the Y-K Delta originated overwhelmingly from western Mexico, while in Nome, there were fewer males from western North America and more from the Baja Peninsula than expected. An unexpectedly high proportion of migrants captured at a stopover site in the interior United States originated from eastern and southern wintering areas, while none originated from western North America. In general, we document substantial mixing between the breeding and wintering populations of both sexes, which will buffer the global population of western sandpipers from the effects of local habitat loss on both breeding and wintering grounds. © 2012 The Authors.
Hodges J.I.,U.S. Fish and Wildlife Service |
Kirchhoff M.D.,Audubon Alaska
Marine Ornithology | Year: 2012
Suspected population declines of the Kittlitz's Murrelet Brachyramphus brevirostris led to selection of the species as a candidate for listing under the Endangered Species Act (USFWS 2004). Kittlitz's Murrelet is currently classified by the International Union for the Conservation of Nature as critically endangered under criterion A4 on the basis of an estimated and projected decline of at least 80% over a period of 36 years (three generations) stretching from 24 years in the past to 12 years in the future (1986-2022) (Taylor 2011). In this paper we evaluate Kittlitz's Murrelet survey data for the initial time frame, from 1986 through present, for Prince William Sound, Alaska. We show that Prince William Sound had factors that would cause the population estimates to be sensitive to misidentification of species. We present evidence that misidentification occurred, and re-analyze the population trend censoring two years with suspected misidentification. We enhance the time series analysis by incorporating two additional years of survey from Kuletz et al. (2011a) - the intensive surveys of 2001 and 2009 - designed specifically for Kittlitz's Murrelets. We also present a non-linear weighted least squares regression, excluding the same two outlying years as Kuletz et al. (2011a) and including their intensive surveys. These analyses indicate no significant decline of Kittlitz's Murrelets in Prince William Sound.