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At least 1,675 records · Page 93Linked to original sources
USGS2013

Seasonal climate variation and caribou availability: Modeling sequential movement using satellite-relocation data

Livelihood systems that depend on mobile resources must constantly adapt to change. For people living in permanent settlements, environmental changes that affect the distribution of a migratory species may reduce the availability of a primary food source, with the potential to destabilize the regional social-ecological system. Food security for Arctic indigenous peoples harvesting barren ground caribou ( Rangifer tarandus granti ) depends on movement patterns of migratory herds. Quantitative assessments of physical, ecological, and social effects on caribou distribution have proven difficult because of the significant interannual variability in seasonal caribou movement patterns. We developed and evaluated a modeling approach for simulating the distribution of a migratory herd throughout its annual cycle over a multiyear period. Beginning with spatial and temporal scales developed in previous studies of the Porcupine Caribou Herd of Canada and Alaska, we used satellite collar locations to compute and analyze season-by-season probabilities of movement of animals between habitat zones under two alternative weather conditions for each season. We then built a set of transition matrices from these movement probabilities, and simulated the sequence of movements across the landscape as a Markov process driven by externally imposed seasonal weather states. Statistical tests showed that the predicted distributions of caribou were consistent with observed distributions, and significantly correlated with subsistence harvest levels for three user communities. Our approach could be applied to other caribou herds and could be adapted for simulating the distribution of other ungulates and species with similarly large interannual variability in the use of their range.

Alaska, Yukon Territory↗
USGS2024

Enhanced petrogenic organic carbon oxidation during the Paleocene-Eocene thermal maximum

The Paleocene-Eocene thermal maximum (PETM; ∼56 Ma) is a hyperthermal event associated with the rapid input of carbon into the ocean-atmosphere system. The oxidation of petrogenic organic carbon (OC petro ) may have released additional carbon dioxide (CO 2 ), thereby prolonging the PETM. However, proxy-based estimates of OC petro oxidation are unavailable due to the lack of suitable techniques. Raman spectroscopy is used to evaluate OC petro oxidation in modern settings. For the first time, we explore whether Raman spectroscopy can evaluate OC petro oxidation during the PETM. In the mid-Atlantic Coastal Plain, there is a shift from disordered to graphitised carbon. This is consistent with enhanced oxidation of disordered OC petro and intensified physical erosion. In the Arctic Ocean, the distribution of graphitised carbon vs . disordered carbon does not change, suggesting limited variability in weathering intensity. Overall, this study provides the first evidence of increased OC petro oxidation during the PETM, although it was likely not globally uniform. Our work also highlights the utility of Raman spectroscopy as a novel tool to reconstruct OC petro oxidation in the past.

Geochemical Perspectives Letters↗
USGS1989

Acute gastric dilatation and volvulus in a free-living polar bear

A large, adult male polar bear ( Ursus maritimus ) was found dead on a barrier island north of Prudhoe Bay, Alaska (USA), in June 1987. There were no external signs of trauma. A twisted distended stomach, distinctive parenchymal and fascial congestion, and significant difficulty in repositioning the anterior abdominal organs, indicated that gastric dilatation-volvulus (GDV) was the proximate cause of death. Polar bears frequently consume large quantities of food at one time and have large stomachs that are well adapted to periodic gorging. The scarcity of food in winter and early spring, combined with voluntary fasting and protracted vigorous activity during the breeding season in late spring may have predisposed this bear to GDV. The relationship between GDV and postprandial exercise emphasizes the need for a better understanding of how the present human invasion of arctic habitats may influence polar bear activities.

Alaska↗
USGS1993

Perinatal mortality in caribou from the Porcupine herd, Alaska

During the 1989 caribou ( Rangifer tarandus ) calving season on the Arctic National Wildlife Refuge, Alaska (USA), 61 calf carcasses were examined for cause of death and associated pathology. Dead calves were located by low-level aerial searches with two fixed-wing aircraft and a helicopter over high density calving areas between the Hulahula and Aichilik rivers. Primary diagnoses included emaciation (39%), malnutrition (8%), stillbirth (21%), trauma (16%), other primary causes (7%), and undetermined causes (8%). Twenty calves had contributory renal tubular degeneration. The findings indicate that factors contributing to nutritional deprivation in calves were the major cause of neonatal mortality; however, factors affecting stillbirth, abortion, or the urogenital system may have major effects on neonatal caribou and warrant further investigation.

Alaska↗
USGS2015

Prevalence and spatio-temporal variation of an alopecia syndrome in polar bears (Ursus maritimus) of the southern Beaufort Sea

Alopecia (hair loss) has been observed in several marine mammal species and has potential energetic consequences for sustaining a normal core body temperature, especially for Arctic marine mammals routinely exposed to harsh environmental conditions. Polar bears ( Ursus maritimus ) rely on a thick layer of adipose tissue and a dense pelage to ameliorate convective heat loss while moving between sea ice and open water. From 1998 to 2012, we observed an alopecia syndrome in polar bears from the southern Beaufort Sea of Alaska that presented as bilaterally asymmetrical loss of guard hairs and thinning of the undercoat around the head, neck, and shoulders, which, in severe cases, was accompanied by exudation and crusted skin lesions. Alopecia was observed in 49 (3.45%) of the bears sampled during 1,421 captures, and the apparent prevalence varied by years with peaks occurring in 1999 (16%) and 2012 (28%). The probability that a bear had alopecia was greatest for subadults and for bears captured in the Prudhoe Bay region, and alopecic individuals had a lower body condition score than unaffected individuals. The cause of the syndrome remains unknown and future work should focus on identifying the causative agent and potential effects on population vital rates.

Beaufort Sea↗
USGS2018

Evidence for haemosporidian parasite infections in Spectacled Eiders (Somateria fischeri) sampled in Alaska during the breeding season

We assessed hematozoa infection in Spectacled Eiders ( Somateria fischeri ) at two areas in Alaska. No Haemoproteus or Plasmodium species were detected. Leucocytozoon prevalence was 6.5% for adults across sites and 41.9% for juveniles sampled in the Arctic, providing evidence for local transmission. All Leucocytozoon haplotypes were previously detected in waterfowl.

Alaska↗
USGS2023

Survey for selected parasites in Alaska brown bears (Ursus arctos)

To assess infection with or exposure to endo- and ectoparasites in Alaska brown bears ( Ursus arctos ), blood and fecal samples were collected during 2013–17 from five locations: Gates of the Arctic National Park and Preserve; Katmai National Park; Lake Clark National Park and Preserve; Yakutat Forelands; and Kodiak Island. Standard fecal centrifugal flotation was used to screen for gastrointestinal parasites, molecular techniques were used to test blood for the presence of Bartonella and Babesia spp., and an ELISA was used to detect antibodies to Sarcoptes scabiei , a species of mite recently associated with mange in American black bears ( Ursus americanus ). From fecal flotations ( n =160), we identified the following helminth eggs: Uncinaria sp. ( n =16, 10.0%), Baylisascaris sp. ( n =5, 3.1%), Dibothriocephalus sp. ( n =2, 1.2%), and taeniid-type eggs ( n =1, 0.6%). Molecular screening for intraerythrocytic parasites ( Babesia spp.) and intracellular bacteria ( Bartonella spp.) was negative for all bears tested. We detected antibodies to S. scabiei in six of 59 (10.2%) individuals. The relatively low level of parasite detection in this study meets expectations for brown bear populations living in large, relatively undisturbed habitats near the northern edge of the range. These results provide a contemporary understanding of parasites in Alaska brown bears and establish baseline levels of parasite presence to monitor for changes over time and relative to ecologic alterations.

Alaska↗
USGS2014

Alaska

Key Messages Arctic summer sea ice is receding faster than previously projected and is expected to virtually disappear before mid-century. This is altering marine ecosystems and leading to greater ship access, offshore development opportunity, and increased community vulnerability to coastal erosion. Most glaciers in Alaska and British Columbia are shrinking substantially. This trend is expected to continue and has implications for hydropower production, ocean circulation patterns, fisheries, and global sea level rise. Permafrost temperatures in Alaska are rising, a thawing trend that is expected to continue, causing multiple vulnerabilities through drier landscapes, more wildfire, altered wildlife habitat, increased cost of maintaining infrastructure, and the release of heat-trapping gases that increase climate warming. Current and projected increases in Alaska’s ocean temperatures and changes in ocean chemistry are expected to alter the distribution and productivity of Alaska’s marine fisheries, which lead the U.S. in commercial value. The cumulative effects of climate change in Alaska strongly affect Native communities, which are highly vulnerable to these rapid changes but have a deep cultural history of adapting to change.

Alaska↗
USGS1977

Demographic features of a lapland longspur population near Barrow, Alaska

Breeding density, clutch size, hatching and fledging success, and survival of adult Lapland Longspurs ( Calcarius lapponicus ) were monitored over a 7-year period near the Naval Arctic Research Laboratory, Barrow, Alaska. Nesting begins as soon as the tundra starts to clear of snow and appears to be timed so that the young of the year reach independence before the end of adult insect emergence. Arthropod prey become abruptly scarce after the period of insect emergence and thus probability of success for late broods is low. Time of nesting is also discussed in relation to factors of predation and timing of molt. At least 42.9% of males and 45.4% of females survived the next season after 1 year of age. Maximum longevity observed for both sexes is 6 years. Mean clutch size for all years investigated was 5.06 eggs per clutch. Clutch size showed both yearly and seasonal variation. The data indicate that timing of nesting is the chief factor in the observed clutch size differences, further modified by habitat quality, second nesting attempts, and probably age of female. Over a 4-year period the longspur breeding population on a 17-ha study plot declined from 15 to 2 breeding females. Life-table analysis indicates that low fledgling success for 3 consecutive years apparently was the main cause of this decline. Overall mean egg success was 44.0%, but close to 60% in 4 years considered more "normal." The low egg success was due to 3 consecutive years of high predation, which may have been related to the disrupted lemming cycle of the Barrow region.

The Auk↗
USGS1996

Demographic characteristics of molting black brant near Teshekpuk Lake, Alaska

Molting Brant in the Teshekpuk Lake Special Area (TLSA) on the Arctic Coastal Plain of Alaska were studied from 1987 to 1992 using capture-mark-recapture techniques to determine origin, age and sex composition, return rates and site fidelity. Brant originated from 10 nesting colonies in Canada and Alaska. The captured birds were 76% adults and 57% males. Ninety-one percent of known-age recaptures were

Journal of Field Ornithology↗
USGS1998

Organochlorine pesticides, PCBs, and mercury in hawk, falcon, eagle, and owl eggs from the Lipetsk, Voronezh, Novgorod and Saratov regions, Russia, 1992-1993

Fifty-two eggs (one per nest) of 12 species of raptors were collected in 1992-93 for contaminant analysis in three southern European locations in Russia. One Peregrine Falcon ( Falco peregrinus ) egg was also collected farther northwest in the Novgorod region. A high DDE concentration (27.3 ppm, wet weight [w/w]) in the Peregrine Falcon egg raised concern for the species in European Russia south of the Arctic Circle. Although a number of organochlorine contaminants were found in eggs of the other species, concentrations were all below known effect levels. Mercury levels were also extremely low. Nesting success in southern Russia in 1992 (only year with follow-up visits) appeared normal.

Journal of Raptor Research↗
USGS1984

[Book review] The wildfowl of Britain and Europe

Of about 140 extant species of waterfowl in the world, 54 occur in the western Pale- arctic. In this, his most recent book, Ogilvie introduces the reader to the waterfowl of Europe including occasional visitors and introduced species. Although written primarily for laymen, ornithologists will find the book informative but should not expect a major treatise on European waterfowl. The text is drawn primarily from Volume I of "The hand-book of the birds of Europe, North Africa, and the Middle East: the birds of the Western Palearctic," of which the author was an editor.

The Auk↗
USGS2002

Polar Bears

Polar bears ( Ursus maritimus ) are hunted throughout most of their range. In addition to hunting polar bears of the Beaufort Sea region are exposed to mineral and petroleum extraction and related human activities such as shipping road-building, and seismic testing (Stirling 1990). Little was known at the start of this project about how polar bears move about in their environment, and although it was understood that many bears travel across political borders, the boundaries of populations had not been delineated (Amstrup 1986, Amstrup et al. 1986, Amstrup and DeMaster 1988, Garner et al. 1994, Amstrup 1995, Amstrup et al. 1995, Amstrup 2000). As human populations increase and demands for polar bears and other arctic resources escalate, managers must know the sizes and distributions of the polar bear populations. Resource managers also need reliable estimates of breeding rates, reproductive intervals, litter sizes, and survival of young and adults. Our objectives for this research were 1) to determine the seasonal and annual movements of polar bears in the Beaufort Sea, 2) to define the boundaries of the population(s) using this region, 3) to determine the size and status of the Beaufort Sea polar bear population, and 4) to establish reproduction and survival rates (Amstrup 2000).

Alaska, Northwest Territories, Yukon Territory↗
USGS2005

The Program for Regional and International Shorebird Monitoring (PRISM)

This report describes the "Program for Regional and International Shorebird Monitoring" (PRISM). PRISM is being implemented by a Canada-United States Shorebird Monitoring and Assessment Committee formed in 2001 by the Canadian Shorebird Working Group and the U.S. Shorebird Council. PRISM provides a single blueprint for implementing the shorebird conservation plans recently completed in Canada and the United States. The goals of PRISM are to (1) estimate the size of breeding population of 74 shorebird taxa in North America; (2) describe the distribution, abundance, and habitat relationships for each of these taxa; (3) monitor trends in shorebird population size; (4) monitor shorebird numbers at stopover locations, and; (5) assist local managers in meeting their shorebird conservation goals. PRISM has four main components: arctic and boreal breeding surveys, temperate breeding surveys, temperate non-breeding surveys, and neotropical surveys. Progress on, and action items for, each major component are described. The more important major tasks for immediate action are carrying out the northern surveys, conducting regional analyses to design the program of migration counts, and evaluating aerial photographic surveys for migration and winter counts.

General Technical Report↗
USGS1985

Alaska peregrine falcon productivity in 1984 and the role of organochlorine residues

Twenty Peregrine Falcon (Falco peregrinus) eggs (one per eyrie) were collected at random in Alaska in 1984 for organochlorine residue analysis. Prior to this study we had obtained only addled eggs which were possibly not representative of the egg-laying population if addled eggs contained different levels of organochlorines than viable eggs that hatched. Ten eggs were collected from the American (anatum) population (8 upper Yukon River, 2 Tanana River) and 10 eggs from the Arctic (tundrius) popUlation were later collected in the study area. Productivity at specific eyries and eggshell thickness were evaluated in relation to residue burdens in sample eggs collected. Residue levels and residue profiles for the two subspecies were compared. The tentative 'critical' residue level in Peregrine eggs of 15-20 ppm DDE (wet weight) was compared to results obtained from this study. We also present some data on residue levels in prey species from the study area.

Book chapter↗
USGS1992

Distribution and color variation of gyrfalcons in Russia

Gyrfalcon (Falco rusticolus) museum specimens in Moscow (73) and St. Petersburg (132) were divided into four color classes (gray, light gray, white gray, and white) and four longitudinal belts representing major physiographic regions of northern Russia. Gray variants predominated in the west and central regions. White birds were most common in extreme eastern Siberia, but were occasionally found even west of the Ural Mountains. Frequencies were as follows: European Russia 4% white, 50% gray (the remainder were intermediates); western Siberia 0% white, 58% gray; central Siberia 15% white, 42% gray; and eastern Siberia 47% white, 33% gray. Remarkably, in the easternmost subregion, white birds predominated even near the southernmost extension. Because the northernmost portions of the species' range in continental Russia are in central Siberia where white variants were rare, we propose that a better predictor of the white variant is longitude, not latitude. White birds were most frequent at the eastern reaches of both the Palearctic and Nearctic. The best environmental correlates of this distribution pattern may be the southward bending thermal isoclines proceeding eastward toward Greenland or Kamchatka, where both land masses are bathed by cold oceanic currents of Arctic origin. By contrast, the western reaches of both land masses are bathed by warm currents. In these western reaches, Gyrfalcon summer distribution is displaced northward and dark variants predominate. The breeding range of the Gyrfalcon, determined by mapping the locations of the specimens we examined, differs little from the range proposed in 1951.

Journal of Raptor Research↗
USGS1996

Wolf pack witness

Arctic wolves have almost never come in contact with humans because of their location in the extreme northern latitudes. Their lack of experience with human intruders makes them an easy species to study.

Audubon↗
USGS2002

Three geese resembling Gray-Bellied Brant/Lawrence's Brant from Long Island, New York

Three oddly plumaged brant, intermediate in several respects between 'Atlantic' or 'Pale-bellied Brant' (hrota) and ?Black Brant? (nigricans) were photographed and described on western Long Island, New York during 2002 (two in March, the third in October). Their plumage corresponded to that of the little-studied, and apparently genetically distinctive small population known among goose biologists as 'Gray-bellied Brant,' which breeds only on a few islands in the western Canadian High Arctic, stages in migration in the inner Aleutians, and winters in a small portion of the Greater Puget Sound area. But Gray-bellied Brant also wander, having recently been found in winter as far from Puget Sound as Baja California in the west, and Iceland and the British Isles to the east?these strays presumably having migrated southwest with Pacific-wintering nigricans and southeast with Atlantic-wintering hrota, respectively. Despite their tendency to associate with locally wintering hrota and nigricans, mixed pairs or hybrid young involving these vagrants have never been demonstrated in North America?nor have mixed pairs or hybrid young between hrota and nigricans, despite widespread belief to the contrary. Complicating the picture is that the type specimen of nigricans, a distinctive New Jersey specimen collected in 1846, also differs from 'true' Pacific Coast Black Brant in several respects, in a manner qualitatively similar to the LI birds described herein. The appearance of the type, often referred to informally as 'Lawrence?s Brant,' differs from typical Black Brant to such an extent that Delacour and Zimmer (1952) rejected application of nigricans to Pacific Black Brant, to which the name orientalis would have to be applied instead. Recent examination of museum specimens of breeding- and winter-area Gray-bellies confirms that Lawrence?s Brant closely resembles some of them?as do these three Long Island birds. Whatever the ultimate statuses of Gray-bellied and Lawrence's Brant prove to be?and however the relationships among them and the three currently recognized other taxa of brant eventually play out?birds resembling Gray-bellied/Lawrence?s are occurring on both Atlantic and Pacific coasts and perhaps also in interior North America, so knowledge of their plumage variation should now be factored into the identification of all oddly-plumaged or out-of-range brant, but especially of putative 'nigricans' inland or on the Atlantic Coast.

North American Birds↗