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.
Prichard A.K.,Inc. Environmental Research and Services |
Joly K.,National Park Service |
Dau J.,Alaska Department of Fish and Game
Journal of Wildlife Management | Year: 2012
Radiotelemetry collars are frequently used to estimate demographic parameters of animals, such as annual survival and parturition rates. If animals are collared for multiple years and statistical adjustments are not made, these estimates can be biased by an unrepresentative age structure and individual variability of collared animals. To quantify the effects of different factors on the magnitude of these potential biases, we created a computer simulation of the female portion of a barren-ground caribou (Rangifer tarandus granti) herd and then randomly assigned collars to individuals within the simulated population. Under our default model, based on the Western Arctic Herd monitoring program, caribou were collared randomly from all females aged 2 years and over, and they remained collared for a mean of 7 years. Our simulations revealed that survival rates were underestimated by approximately 3.4% and parturition rates were overestimated by approximately 3.3%. The magnitude of these biases increased when individuals remained collared for longer periods. Increased individual variability in the population resulted in only small increases in survival and parturition rates. Because the magnitude of the bias increased steadily during the first years of the study, we found a substantial risk of incorrectly identifying a significant decline in survival in the first 7 years after marking. Including the number of years individual animals have been collared as a covariate in analyses can reduce the biases in demographic parameters and should be considered for inclusion in analyses when animal age is unknown. Actual survival rate estimates from telemetry data for the Western Arctic Herd were generally consistent with the results of these simulations. These potential biases should be considered when interpreting demographic parameters from multi-year collaring studies. © 2012 The Wildlife Society. Copyright © The Wildlife Society, 2012.
Macander M.J.,Inc. Environmental Research and Services |
Swingley C.S.,Inc. Environmental Research and Services |
Joly K.,National Park Service |
Raynolds M.K.,Inc. Environmental Research and Services |
Raynolds M.K.,University of Alaska Fairbanks
Remote Sensing of Environment | Year: 2015
Landsat imagery for northwest Alaska from 1 February to 31 August, 1985-2011 was used to map snow persistence at high spatial resolution. We analyzed 11,645 scenes covering 505,800km2, including five Arctic National Park units and the range of the Western Arctic caribou herd (85 Landsat path/rows). A cloud mask was created using the Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS). Terrain shadows were calculated from ASTER G-DEM2 and solar incidence angle. The presence of snow cover was determined using separate Snowmap algorithms for non-shadowed and shadowed pixels. Resulting snow cover data were reformatted into 562 30×30km tiles, with an average sample size per pixel of 216 cloud-free observations. A binary classification tree was used to successfully determine the day of the year that best marked the change from snow to snow-free conditions for 99.8% of the study area. An internal consistency check evaluating the occurrence of snow-free data earlier than that day or snow data later than that day, showed that 98.7% of the land pixels were consistently classified ≥90% of the time. Comparison with MODIS end of snow season data showed an average difference of 4.2days. The snow persistence map was strongly correlated with the few SNOTEL stations in the study area (r2=0.856). Broadly, most snowmelt over the study area occurs from late April through early June, with timing delayed farther north and at higher elevations. Many local-scale snow patterns are evident in the detailed, 30-m product. The snow persistence map was co-registered to Landsat land cover mapping, creating a powerful, publicly available resource for ecosystem and land use analyses (https://irma.nps.gov/App/Reference/Profile/2203863). © 2015 Elsevier Inc.
Frost G.V.,University of Virginia |
Frost G.V.,Inc. Environmental Research and Services |
Epstein H.E.,University of Virginia
Global Change Biology | Year: 2014
Circumpolar expansion of tall shrubs and trees into Arctic tundra is widely thought to be occurring as a result of recent climate warming, but little quantitative evidence exists for northern Siberia, which encompasses the world's largest forest-tundra ecotonal belt. We quantified changes in tall shrub and tree canopy cover in 11, widely distributed Siberian ecotonal landscapes by comparing very high-resolution photography from the Cold War-era 'Gambit' and 'Corona' satellite surveillance systems (1965-1969) with modern imagery. We also analyzed within-landscape patterns of vegetation change to evaluate the susceptibility of different landscape components to tall shrub and tree increase. The total cover of tall shrubs and trees increased in nine of 11 ecotones. In northwest Siberia, alder (Alnus) shrubland cover increased 5.3-25.9% in five ecotones. In Taymyr and Yakutia, larch (Larix) cover increased 3.0-6.7% within three ecotones, but declined 16.8% at a fourth ecotone due to thaw of ice-rich permafrost. In Chukotka, the total cover of alder and dwarf pine (Pinus) increased 6.1% within one ecotone and was little changed at a second ecotone. Within most landscapes, shrub and tree increase was linked to specific geomorphic settings, especially those with active disturbance regimes such as permafrost patterned-ground, floodplains, and colluvial hillslopes. Mean summer temperatures increased at most ecotones since the mid-1960s, but rates of shrub and tree canopy cover expansion were not strongly correlated with temperature trends and were better correlated with mean annual precipitation. We conclude that shrub and tree cover is increasing in tundra ecotones across most of northern Siberia, but rates of increase vary widely regionally and at the landscape scale. Our results indicate that extensive changes can occur within decades in moist, shrub-dominated ecotones, as in northwest Siberia, while changes are likely to occur much more slowly in the highly continental, larch-dominated ecotones of central and eastern Siberia. © 2013 John Wiley & Sons Ltd.
Harwell M.A.,Harwell Gentile and Associates |
Gentile J.H.,Harwell Gentile and Associates |
Parker K.R.,Data Analysis Group |
Murphy S.M.,Inc Environmental Research and Services |
And 4 more authors.
Human and Ecological Risk Assessment | Year: 2012
Harlequin Ducks (Histrionicus histrionicus) were adversely affected by the Exxon Valdez oil spill (EVOS) in Prince William Sound (PWS), Alaska, and some have suggested effects continue two decades later. We present an ecological risk assessment evaluating quantitatively whether PWS seaducks continue to be at-risk from polycyclic aromatic hydrocarbons (PAHs) in residual Exxon Valdez oil. Potential pathways for PAH exposures are identified for initially oiled and never-oiled reference sites. Some potential pathways are implausible (e.g., a seaduck excavating subsurface oil residues), whereas other pathways warrant quantification. We used data on PAH concentrations in PWS prey species, sediments, and seawater collected during 2001-2008 to develop a stochastic individual-based model projecting assimilated doses to seaducks. We simulated exposures to 500,000 individuals in each of eight age/gender classes, capturing the variability within a population of seaducks living in PWS. Doses to the maximum-exposed individuals are ~400-4,000 times lower than chronic toxicity reference values established using USEPA protocols for sea-ducks. These exposures are so low that no individual-level effects are plausible, even within a simulated population that is orders-of-magnitude larger than exists in PWS. We conclude that toxicological risks to PWS seaducks from residual Exxon Valdez oil two decades later are essentially non-existent. © 2012 Copyright Taylor and Francis Group, LLC.
Cater T.C.,Inc. Environmental Research and Services |
Hopson C.,UMIAQ |
Streever B.,BP Exploration Alaska Inc
Arctic | Year: 2015
Tundra sodding, a new technique available to rehabilitate disturbed wetlands in the Arctic, is based on Iñupiaq traditional knowledge. C. Hopson, an Iñupiaq elder from Barrow and author of this paper, guided the development and field application of this new technique by providing traditional knowledge he learned as a youth from his elders. Tundra sodding has several advantages over other land rehabilitation techniques, the most important being that it can establish a mature plant community of indigenous species in a single growing season. In all sampling years, the plant communities at sodded sites were dominated by two rhizomatous graminoids, Eriophorum angustifolium and Carex aquatilis. These sedges also were dominant in all years in reference tundra. Also common to the plant communities in both reference tundra and sodded sites were 18 other vascular species (grasses, evergreen and deciduous shrubs, and forbs). Results from two to five growing seasons indicate that tundra sod can reduce the overall subsidence due to thawing of shallow permafrost. We harvested sod on three occasions from an area slated for gravel mining. In the summers of 2007 and 2008, we transplanted 334 m2 of tundra sod to portions of three sites to test the feasibility of the method. In summer 2010, we used the experience gained from that work to rehabilitate an entire site (1114 m2). This tundra sodding technique is labor intensive and costly compared to other rehabilitation techniques, but it offers advantages that justify its use when rapid rehabilitation of a disturbed site is needed. © The Arctic Institute of North America.
Jones N.F.,Colorado State University |
Jones N.F.,Inc. Environmental Research and Services |
Pejchar L.,Colorado State University
PLoS ONE | Year: 2013
Energy production in the United States is in transition as the demand for clean and domestic power increases. Wind energy offers the benefit of reduced emissions, yet, like oil and natural gas, it also contributes to energy sprawl. We used a diverse set of indicators to quantify the ecological impacts of oil, natural gas, and wind energy development in Colorado and Wyoming. Aerial imagery was supplemented with empirical data to estimate habitat loss, fragmentation, potential for wildlife mortality, susceptibility to invasion, biomass carbon lost, and water resources. To quantify these impacts we digitized the land-use footprint within 375 plots, stratified by energy type. We quantified the change in impacts per unit area and per unit energy produced, compared wind energy to oil and gas, and compared landscapes with and without energy development. We found substantial differences in impacts between energy types for most indicators, although the magnitude and direction of the differences varied. Oil and gas generally resulted in greater impacts per unit area but fewer impacts per unit energy compared with wind. Biologically important and policy-relevant outcomes of this study include: 1) regardless of energy type, underlying land-use matters and development in already disturbed areas resulted in fewer total impacts; 2) the number and source of potential mortality varied between energy types, however, the lack of robust mortality data limits our ability to use this information to estimate and mitigate impacts; and 3) per unit energy produced, oil and gas extraction was less impactful on an annual basis but is likely to have a much larger cumulative footprint than wind energy over time. This rapid evaluation of landscape-scale energy development impacts could be replicated in other regions, and our specific findings can help meet the challenge of balancing land conservation with society's demand for energy. © 2013 Jones Pejchar.
Stickney A.A.,Inc. Environmental Research and Services |
Obritschkewitsch T.,Inc. Environmental Research and Services |
Burgess R.M.,Inc. Environmental Research and Services
Arctic | Year: 2014
Although shifts in the distribution of red foxes into areas previously dominated by Arctic foxes have been documented over wide areas of the circumpolar North, no such documentation exists yet for the Alaskan Arctic. Fox research in the greater Prudhoe Bay area from the 1970s through the early 1990s focused primarily on Arctic foxes in relation to oil development because red foxes were uncommon. A monitoring program in 2005 - 12 included annual surveys of 31 - 48 fox dens within 2 km of the road system. In 2005, 2006, and 2008, Arctic fox dens outnumbered those of red foxes, but from 2010 onward, the reverse was true. There is greater distance between natal dens of Arctic foxes and those of red foxes than between natal dens within each species, suggesting that Arctic foxes avoid red fox denning territories. Of dens in our study that were used by Arctic foxes prior to 2005, 50% have since been occupied by red foxes. Red foxes displaced Arctic foxes from dens closest to oil field camps, pads, and other facilities, and preyed on their pups. Access to anthropogenic food sources probably supports red foxes in the area. Predictions from climate change studies indicate the displacement of Arctic foxes by red foxes will continue in the Alaskan Arctic, although the change may be slower away from areas of human occupation and anthropogenic foods. © The Arctic Institute of North America.
Day R.H.,Inc. Environmental Researchand Services |
Gall A.E.,Inc. Environmental Researchand Services |
Morgan T.C.,Inc. Environmental Researchand Services |
Rose J.R.,Inc. Environmental Researchand Services |
And 5 more authors.
Western Birds | Year: 2013
Seabirds at high latitudes may respond to climate change in a variety of ways, including range contractions or expansions and/or seasonal or annual shifts in distribution. Since 2006, three species of seabirds have been reported in the eastern Chukchi Sea for the first time: the Short-tailed Albatross (Phoebastria albatrus), Northern Gannet (Morus bassanus), and Rhinoceros Auklet (Cerorhinca monocerata). Sometime prior to 2006, the Ancient Murrelet (Synthliboramphus antiquus) expanded its usual maritime range north into the eastern Chukchi and now has reached the Beaufort Sea. The gannet appears to have entered the Pacific via the Northwest Passage, whereas the other three species have moved north from the Pacific. Whales, other seabirds, and diatoms have been recorded moving between the Atlantic and Pacific via the Northwest Passage in the past 15 years as sea ice has retreated and the passage has opened. Because of broad-scale changes to the Chukchi ecosystem and because of increased sampling of the region, we anticipate that additional seabirds will be recorded in the Chukchi and Beaufort seas from the North Pacific and possibly the North Atlantic.
Day R.H.,Inc. Environmental Research and Services |
Gall A.E.,Inc. Environmental Research and Services |
Prichard A.K.,Inc. Environmental Research and Services |
Divoky G.J.,652 32nd Avenue East |
Rojek N.A.,U.S. Fish and Wildlife Service
Marine Ornithology | Year: 2011
We summarize information on the status, distribution and abundance of Kittlitz's Murrelet Brachyramphus brevirostris in northern Alaska, an area for which little information is available. Nine, and possibly 11, nests of Kittlitz's Murrelets have been found in northern Alaska; a substantial amount of potential nesting habitat appears to be unoccupied, especially in and near inner Norton and Kotzebue sounds. There are extensive records (museum, sight, photographic, aerial-survey and at-sea) of Kittlitz's Murrelets in the eastern Chukchi Sea from Cape Prince of Wales to Point Barrow and two recent records from the Beaufort Sea. The population of Kittlitz's Murrelet in northern Alaska was an estimated 450 birds during the breeding season (April-August) and 8500 birds in the post-breeding season (September-October), although 95% CIs for the latter estimate were large. There was no overlap, however, in CIs between the breeding and post-breeding seasons, indicating that a large number of murrelets move into the region during the latter period. At sea, the species was found over the shelf of the Chukchi Sea during a 7-month period from mid-April to mid- or late October, with the highest densities occurring within 50 km of shore. There was strong evidence from at-sea data for seasonal variation in abundance (highest densities in September-October), but there was no evidence for population change between the periods 1970-1999 and 2000-2009 during either the breeding or post-breeding seasons. Information presented here indicates that the Kittlitz's Murrelet is widespread and fairly common at times in the Chukchi Sea but is rare and casual (not annual) in the Beaufort Sea.