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At least 55 records · Page 3Linked to original sources
USGS2013

Introduction to the fifth Mars Polar Science special issue: key questions, needed observations, and recommended investigations

The Fifth International Conference on Mars Polar Science and Exploration – which was held from September 12–16, 2011, at the Pike’s Waterfront Lodge in Fairbanks, Alaska – is the latest in a continuing series of meetings that are intended to promote the exchange of knowledge and ideas between planetary and terrestrial scientists interested in Mars polar and climate research (http://www.lpi.usra.edu/meetings/polar2011/polar20113rd.html). The conference was sponsored by the Lunar and Planetary Institute, National Aeronautics and Space Administration, NASA’s Mars Program Office, University of Alaska Fairbanks, International Association of Cryospheric Sciences and the Centre for Research in Earth and Space Sciences at York University.

Icarus↗
USGS2001

Evaluation of flash-flood discharge forecasts in complex terrain using precipitation

Operational prediction of flash floods produced by thunderstorm (convective) precipitation in mountainous areas requires accurate estimates or predictions of the precipitation distribution in space and time. The details of the spatial distribution are especially critical in complex terrain because the watersheds are generally small in size, and small position errors in the forecast or observed placement of the precipitation can distribute the rain over the wrong watershed. In addition to the need for good precipitation estimates and predictions, accurate flood prediction requires a surface-hydrologic model that is capable of predicting stream or river discharge based on the precipitation-rate input data. Different techniques for the estimation and prediction of convective precipitation will be applied to the Buffalo Creek, Colorado flash flood of July 1996, where over 75 mm of rain from a thunderstorm fell on the watershed in less than 1 h. The hydrologic impact of the precipitation was exacerbated by the fact that a significant fraction of the watershed experienced a wildfire approximately two months prior to the rain event. Precipitation estimates from the National Weather Service's operational Weather Surveillance Radar-Doppler 1988 and the National Center for Atmospheric Research S-band, research, dual-polarization radar, colocated to the east of Denver, are compared. In addition, very short range forecasts from a convection-resolving dynamic model, which is initialized variationally using the radar reflectivity and Doppler winds, are compared with forecasts from an automated-algorithmic forecast system that also employs the radar data. The radar estimates of rain rate, and the two forecasting systems that employ the radar data, have degraded accuracy by virtue of the fact that they are applied in complex terrain. Nevertheless, the radar data and forecasts from the dynamic model and the automated algorithm could be operationally useful for input to surface-hydrologic models employed for flood warning. Precipitation data provided by these various techniques at short time scales and at fine spatial resolutions are employed as detailed input to a distributed-parameter hydrologic model for flash-flood prediction and analysis. With the radar-based precipitation estimates employed as input, the simulated flood discharge was similar to that observed. The dynamic-model precipitation forecast showed the most promise in providing a significant discharge-forecast lead time. The algorithmic system's precipitation forecast did not demonstrate as much skill, but the associated discharge forecast would still have been sufficient to have provided an alert of impending flood danger.

Journal of Hydrologic Engineering↗
USGS2026

Timing the tuxedo transformation: Moult phenology reflects breeding investment and intrinsic constraints in Adélie penguins

Vertebrate life histories are often divided into distinct periods, with the breeding season typically receiving the most research attention. For polar seabirds, non-breeding phases like moult remain understudied, despite their importance for survival and overall fitness. Adélie penguins ( Pygoscelis adeliae ) replace their highly specialized feathers during an approximately 19-day annual moult, typically carried out while fasting on sea ice. The required fast and elevated metabolic rate may create a significant energetic bottleneck. We analysed data from geolocating dive recorders deployed on known-age Adélie penguins and non-known-age pairs from two Ross Island colonies over three winters (2017–2019). Moult start date was influenced by breeding success, intrinsic factors (age, sex) and extrinsic factors (year), with males, older birds and successful breeders moulting later. Moult duration varied primarily with individual ID, though later initiation correlated with shorter duration, particularly when located further south. Moult duration was longer in the western Ross Sea, a region that was used exclusively by males. The association between moult start date and duration may lead to differential sex and breeding status effects, with older males more likely to face a trade-off between successful breeding and self-maintenance tasks like feather replacement.

Proceedings of the Royal Society B↗
USGS1992

An aeromagnetic survey over the northwestern Ross Ice Shelf and the McMurdo Sound area

As part of the expedition GANOVEX VI 1990/91, the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), the Alfred Wegener Institute for Polar and Marine Research (AWI), and the United States Geological Survey (USGS) carried out an airborne magnetic survey over the northwestern Ross Ice Shelf and McMurdo Sound between Ross Island, the Transantarctic Mountains, and Minna Bluff. The area planned for the aeromagnetic survey connects directly with the GANOVEX IV survey area (BGR & USGS 1987, BACHEM et al. 1989a) which terminated along an approximately cast-west line at about the latitude of Cape Bird. The GANOVEX IV survey covered the Victoria Land Basin - which is the westernmost of the three north/south striking basins in the Ross Sea - from its northern end in the Terra Nova Bay region to its known southern end at Ross Island. A possible southem extension of the Victoria Land Basin and its central graben structure (the Terror Rift as found from seismic surveys (COOPER et al. 1987) and what has been referred to as Victoria Graben in the aeromagnetic interpretation of the GANOVEX IV data (BOSUM et al. 1989) was one of the major targets for this survey. The survey was laid out in the form of blocks. A 135 km wide transect from the Transantarctic Mountains to about 175° W formed the focal block of the survey (Fig. 1) in which all major scientific objectives could be covered. Other survey blocks were planned to the south of this. During the course of the survey it turned out that in the time available no further area could be covered. Indeed, the unfavourable weather conditions made it impossible to complete even the above described main section fully. In detail, the lay-out of the survey area was closely following that of the GANOVEX IV survey to assure compatibility and direct continuation between the two data sets. The line spacing was chosen again to 4.4 km with a tic-line separation of 22 km. The survey altitude of 2,000 ft (610 m) corresponds to that of the Ross Sea section of the GANOVEX IV survey to which this survey area is directly adjacent. The profile lines were aligned approximately E-W, the tie-lines N-S. As part of the survey area is covered by the maps of the USGS Antarctica Reconnaissance Series 1:250,000 the Lambert conformal conic projection used for these maps was also used for the preparation of a flight line grid.

Polarforschung↗
USGS2007

Unconsolidated sediments at the bottom of Lake Vostok from seismic data

Seismic soundings of Lake Vostok have been performed by the Polar Marine Geological Research Expedition in collaboration with the Russian Antarctic Expedition since the early 1990s. The seismograms recorded show at least two relatively closely spaced reflections associated with the lake bottom. These were initially interpreted as boundaries of a layer of unconsolidated sediments at the bottom of the lake. A more recent interpretation suggests that the observed reflections are side echoes from the rough lake bottom, and that there are no unconsolidated sediments at the bottom of the lake. The major goal of this paper is to reveal the nature of those reflections by testing three hypotheses of their origin. The results show that some of the reflections, but not all of them, are consistent with the hypothesis of a non-flat lake bottom along the source-receiver line (2D case). The reflections were also evaluated as side echoes from an adjacent sloping interface, but these tests implied unreasonably steep slopes (at least 8 degrees) at the lake bottom. The hypothesis that is the most compatible with seismic data is the presence of a widespread layer of unconsolidated sediments at the bottom of Lake Vostok. The modeling suggests the presence of a two hundred meter thick sedimentary layer with a seismic velocity of 1700 -1900 m/sec in the southern and middle parts of the lake. The sedimentary layer thickens in the northern basin to ~350 m

Open-File Report↗
USGS2013

Distribution of late Pleistocene ice-rich syngenetic permafrost of the Yedoma Suite in east and central Siberia, Russia

This digital database is the product of collaboration between the U.S. Geological Survey, the Geophysical Institute at the University of Alaska, Fairbanks; the Los Altos Hills Foothill College GeoSpatial Technology Certificate Program; the Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany; and the Institute of Physical Chemical and Biological Problems in Soil Science of the Russian Academy of Sciences. The primary goal for creating this digital database is to enhance current estimates of soil organic carbon stored in deep permafrost, in particular the late Pleistocene syngenetic ice-rich permafrost deposits of the Yedoma Suite. Previous studies estimated that Yedoma deposits cover about 1 million square kilometers of a large region in central and eastern Siberia, but these estimates generally are based on maps with scales smaller than 1:10,000,000. Taking into account this large area, it was estimated that Yedoma may store as much as 500 petagrams of soil organic carbon, a large part of which is vulnerable to thaw and mobilization from thermokarst and erosion. To refine assessments of the spatial distribution of Yedoma deposits, we digitized 11 Russian Quaternary geologic maps. Our study focused on extracting geologic units interpreted by us as late Pleistocene ice-rich syngenetic Yedoma deposits based on lithology, ground ice conditions, stratigraphy, and geomorphological and spatial association. These Yedoma units then were merged into a single data layer across map tiles. The spatial database provides a useful update of the spatial distribution of this deposit for an approximately 2.32 million square kilometers land area in Siberia that will (1) serve as a core database for future refinements of Yedoma distribution in additional regions, and (2) provide a starting point to revise the size of deep but thaw-vulnerable permafrost carbon pools in the Arctic based on surface geology and the distribution of cryolithofacies types at high spatial resolution. However, we recognize that the extent of Yedoma deposits presented in this database is not complete for a global assessment, because Yedoma deposits also occur in the Taymyr lowlands and Chukotka, and in parts of Alaska and northwestern Canada.

Siberia↗
USGS2004

Using Forward Looking Infrared (FLIR) imagery to detect polar bear maternal dens: Operations manual

Recent research has shown that Forward Looking Infia-Red (FLIR) imagery can detect polar bear dens despite total snow cover over their deming habitat. FLIR imagers detect a AT or difference in temperature between objects in the imager's field of view. During the Arctic winter, the groundlsnow surface is typically cold, providing a dark background in the FLIR imager. Sources of heat appear as lighter or white areas. Dens, in particular, appear as small bright "hotspots", usually with kzy boundaries (Appendix 1). Most commonly, since bears chose deep snow drifts for deming, dens can be distinguished from the normally dark (cold) band of drifted snow surrounding them. This innovation has the potential to prevent human activities fiom disturbing deming polar bears by allowing managers to discover dens before potentially disruptive activities begin. This is important because expanding resource extraction in Alaska's Arctic regions may threaten the welfare of polar bears and their habitat. In recent years, exploration and development activities have expanded east and west of the original oil fields of Prudhoe Bay. Hydrocarbon extraction is now occurring or planned along much of the central Beaufort Sea coast. As development continues into the National Petroleum Reserve, the scope of expansion could include 213 of the northern coastal region of Alaska. Industrial activities are a potential threat to polar bears, especially as they might disturb bears in maternal dens (Lentfer and Hensel 1980, Stirling 1990, Stirling and Andriashek 1992, Amstrup 1993, Amstrup and Gardner 1994). As the number of humans and their activities have increased in recent years, there has been a concurrent increase in the number of female polar bears deming on land (Amstrup and Gardner 1994). Therefore, the probability of disrupting maternal deming can be expected to increase in the future. Using FLIR surveys to detect bears in dens could reduce or eliminate that probability. The purpose of this manual is to provide agency and private sector land managers with the information necessary to perform effective FLIR surveys to detect maternal dens. A list of personnel who can provide additional information is provided in Appendix 2.

BOEM↗
USGS2011

Ocean acidification postcards

The U.S. Geological Survey (USGS) is conducting research on ocean acidification in polar, temperate, subtropical, and tropical regions including the Arctic, West Florida Shelf, and the Caribbean. Project activities include field assessment, experimental laboratory studies, and evaluation of existing data. The USGS is participating in international and interagency working groups to develop research strategies to increase understanding of the global implications of ocean acidification. Research strategies include new approaches for seawater chemistry observation and modeling, assessment of physiological effects on organisms, changes in marine ecosystem structure, new technologies, and information resources. These postcards highlight ongoing USGS research efforts in ocean acidification and carbon cycling in marine and coastal ecosystems in three different regions: polar, temperate, and tropical. To learn more about ocean acidification visit: http://coastal.er.usgs.gov/ocean-acidification/.

General Information Product↗
USGS2007

Airborne geophysics as a tool for geoscientific research in Antarctica: some recent examples

The polar regions play an important role in Earth's geodynamic and climatic systems. Modern airborne geophysical surveys combine radio-echo sounding, aeromagnetic and aerogravity methods to explore the geology of these regions. This paper reviews some recent aerogeophysical investigations undertaken by the British Antarctic Survey to: 1) Image subglacial rifts of Jurassic age in western Dronning Maud Land, which were associated with early Gondwana break-up; 2) Investigate crustal growth over the Antarctic Peninsula by Cretaceous arc magmatism and terrane accretion along the paleo-Pacific margin of Gondwana; 3) Analyse geological boundary conditions for presentday ice dynamics over Coats Land.

Open-File Report↗
USGS2015

Distance measures and optimization spaces in quantitative fatty acid signature analysis

Quantitative fatty acid signature analysis has become an important method of diet estimation in ecology, especially marine ecology. Controlled feeding trials to validate the method and estimate the calibration coefficients necessary to account for differential metabolism of individual fatty acids have been conducted with several species from diverse taxa. However, research into potential refinements of the estimation method has been limited. We compared the performance of the original method of estimating diet composition with that of five variants based on different combinations of distance measures and calibration-coefficient transformations between prey and predator fatty acid signature spaces. Fatty acid signatures of pseudopredators were constructed using known diet mixtures of two prey data sets previously used to estimate the diets of polar bears Ursus maritimus and gray seals Halichoerus grypus, and their diets were then estimated using all six variants. In addition, previously published diets of Chukchi Sea polar bears were re-estimated using all six methods. Our findings reveal that the selection of an estimation method can meaningfully influence estimates of diet composition. Among the pseudopredator results, which allowed evaluation of bias and precision, differences in estimator performance were rarely large, and no one estimator was universally preferred, although estimators based on the Aitchison distance measure tended to have modestly superior properties compared to estimators based on the Kullback-Leibler distance measure. However, greater differences were observed among estimated polar bear diets, most likely due to differential estimator sensitivity to assumption violations. Our results, particularly the polar bear example, suggest that additional research into estimator performance and model diagnostics is warranted.

Ecology and Evolution↗
USGS2007

International Polar Year: Science at the Ends of the Earth

In response to unprecedented changes in the fragile polar regions of our planet, the International Polar Year (IPY) 2007-2008 will encompass many scientific studies designed to improve our understanding of polar change and its effects on Earth's ecosystems and people. For 2 years, U.S. Geological Survey (USGS) researchers will don arctic gear and join scientists from more than 60 countries to conduct coordinated research and analysis in the Arctic and Antarctic. Polar regions play a critical role in the global climate system-and changing conditions in these often remote areas greatly affect biological, atmospheric, and human systems around the world. In the 50 years since the last IPY, scientists have seen that Antarctic ice shelves and glaciers worldwide are thinning and retreating, permafrost is thawing, and Arctic sea-ice cover is decreasing. The loss of sea-ice cover adversely affects marine mammal populations and leaves coastal Alaskan villages vulnerable to winter storm erosion. Thawing permafrost threatens the integrity of roads, buildings, and other vulnerable infrastructure and affects the mobility of local populations.

Fact Sheet↗
USGS2018

Summary of wildlife-related research on the coastal plain of the Arctic National Wildlife Refuge, Alaska, 2002–17

We summarize recent (2002–17) publicly available information from studies within the 1002 Area of the Arctic National Wildlife Refuge as well as terrestrial and coastal ecosystems elsewhere on the Arctic Coastal Plain that are relevant to the 1002 Area. This report provides an update on earlier research summaries on caribou (Rangifer tarandus), forage quality and quantity, polar bears (Ursus maritimus), muskoxen (Ovibos moschatus), and snow geese (Chen caerulescens). We also provide information on new research related to climate, migratory birds, permafrost, coastal erosion, coastal lagoons, fish, water resources, and potential effects of industrial disturbance on wildlife. From this literature review, we noted evidence for change in the status of some wildlife and their habitats, and the lack of change for others. In the 1002 Area, muskox numbers have decreased and the Porcupine Caribou Herd has exhibited variation in use of the area during the calving season. Polar bears are now more common on shore in summer and fall because of declines in sea ice in the Beaufort Sea. In a study spanning 25 years, there were no significant changes in vegetation quality and quantity, soil conditions, or permafrost thaw in the coastal plain of the 1002 Area. Based on studies from the central Arctic Coastal Plain, there are persistent and emerging uncertainties about the long-term effects of energy development for caribou. In contrast, recent studies that examined direct and indirect effects of industrial activities and infrastructure on birds in the central Arctic Coastal Plain found little effect for the species and disturbances examined, except for the possibility of increased predator activity near human developments.

Alaska↗
USGS2009

Rebuttal of "Polar bear population forecasts: a public-policy forecasting audit"

Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears ( Ursus maritimus ). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior's listing-decision process, the US Geological Survey (USGS) produced a series of nine research reports evaluating the present and future status of polar bears throughout their range. In response, Armstrong et al. [Armstrong, J. S., K. C. Green, W. Soon. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38 (5) 382–405], which we will refer to as AGS, performed an audit of two of these nine reports. AGS claimed that the general circulation models upon which the USGS reports relied were not valid forecasting tools, that USGS researchers were not objective or lacked independence from policy decisions, that they did not utilize all available information in constructing their forecasts, and that they violated numerous principles of forecasting espoused by AGS. AGS (p. 382) concluded that the two USGS reports were "unscientific and inconsequential to decision makers." We evaluate the AGS audit and show how AGS are mistaken or misleading on every claim. We provide evidence that general circulation models are useful in forecasting future climate conditions and that corporate and government leaders are relying on these models to do so. We clarify the strict independence of the USGS from the listing decision. We show that the allegations of failure to follow the principles of forecasting espoused by AGS are either incorrect or are based on misconceptions about the Arctic environment, polar bear biology, or statistical and mathematical methods. We conclude by showing that the AGS principles of forecasting are too ambiguous and subjective to be used as a reliable basis for auditing scientific investigations. In summary, we show that the AGS audit offers no valid criticism of the USGS conclusion that global warming poses a serious threat to the future welfare of polar bears and that it only serves to distract from reasoned public-policy debate.

Interfaces↗
USGS2023

Incremental evolution of modeling a prognosis for polar bears in a rapidly changing Arctic

Updating predictions of the response of high-profile, at-risk species to climate change and anthropogenic stressors is vital for informing effective conservation action. Here, we review two prior generations of Bayesian network probability models predicting changes in global polar bear ( Ursus maritimus ) population status, and provide a contemporary update based on recent research findings and sea-ice projections by newer climate models. We compare predictions of polar bear population response from all 3 models among four circumpolar Arctic ecoregions, using sea ice projections based on three IPCC greenhouse gas emissions scenarios (SSP2.6, 4.5, 8.5). Consistent with the previous two model generations, polar bears will continue to experience increasing probability of declining or greatly declining populations throughout the 21st century, varying by emission scenario. Populations within the Polar Basin Divergent Ice Ecoregion have the highest predicted probability of declines, but predictions were slightly less dire relative to the previous model generation. Most of the influence, denoted by model sensitivity analysis, is from expected degradation and loss of sea ice and reduced access to marine prey. The lack of terrestrial prey adequate to substitute for loss of access to marine prey, as well as human-caused bear morality associated with hunting and defense of life and property encountered when polar bears are increasingly forced ashore also contributed to predicted declines. Although some tidewater glacial fjords and other localized onshore resources may provide local refugia, their benefit is transient. Our findings continue to inform priorities for inventory, monitoring, and research needs, and suggest that similar updates to models of other at-risk species can capitalize on the comparison framework we present here.

Ecological Indicators↗
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↗
USGS2021

Identifying negative sentiment polarity in the Judas technique

In the context of conservation science and management, the Judas technique refers to outfitting an animal (a Judas animal) with a radio transmitter or other identifier so that its movements can be tracked to locate conspecifics. Although this term is commonly used, some consider it offensive due to historical associations of the word Judas with anti-Semitic sentiments. Thus, the term has a negative sentiment polarity (i.e., the assertion that words can have positive, negative, or neutral connotations). We investigated the etymology of the Judas term in peer-reviewed scientific literature to outline its contextual introduction and use. Prior to the term being co-opted by conservation scientists Judas [animal] was a common term in the livestock industry to describe animals used to lead herds to slaughter. Subsequently, the term has been published and promulgated through conservation-related research and the literature. Due to a negative sentiment polarity linked to this term, especially among members of the public, alternative nomenclature may be preferred to increase objective and dispassionate scientific communication.

Conservation Science and Practice↗
USGS1976

Paleomagnetism of the Plio-Pleistocene sediments of Lake Tecopa, California, and East Rudolf, Kenya; magnetic stratigraphy and polarity transitions

High resolution paleomagnetic records were obtained from Plio-Pleistocene lake deposits in California and Kenya. The objectives of this research were correlation of the stratigraphic sections with the geomagnetic reversal time scale and measurement of the magnetic changes which occur during polarity transitions. In addition, the properties of reliable and unreliable paleomagnetic sediments were investigated. The Brunhes-Matuyama reversal boundary (700,000 years B.P.) was located in the deposits of Lake Tecopa. A detailed study of this polarity transition gave the .following results: 1). .During the transitions the intensity of the field in the southwestern U.S. dropped to a minimum of 10 percent of the intensity after the transition. 2). Intervals of low field intensity preceded and followed the interval during which the field direction reversed, the latter being shorter than the interval of low intensity by a factor of at least 2.5. 3). Pole paths for the Brunhes-Matuyama transition observed in Japan and California are completely different, indicating that the dipole field decayed. The transition field appears to be essentially the non-dipole field. 4). The transitional field may be a stationary non-dipole field, but one which is different during different transitions.. The small amount of drift during polarity transitions may reflect loss of core mantle induction coupling, which is usually provided by the dipole field. Paleomagnetic stratigraphy was determined from the archaeological sites at Lake Rudolf; however, the dating of these deposits remains ambiguous. Two interpretations have been proposed. In the first . xi interpretation the age of the lower member of the Koobi Fora Formation is 2..6 - 3.7 m.y.; whereas, in the second interpretation the age is 1.6 - 3.1 m.y. Studies of rock magnetism showed that in the deposits of both lakes the magnetic remanence is carried by grains of oxidized titano-magnetite, most with diameters ranging between 1 and 100 microns. At Lake Tecopa the least reliable paleomagnetic results were found in sediments which had undergone diagenesis in a highly oxidizing environment. In a comparison of magnetically stable and unstable specimens from Lake Rudolf, it was found that stability depended on grain size. Stable magnetic behavior was observed in sediments in which the bulk of the magnetic grains had diameters of less than 20 microns. Specimen: which contained large proportions of grains with diameters greater than 50 microns tended to be unstable.

California↗
USGS2010

Catalogue of polar bear (Ursus maritimus) maternal den locations in the Beaufort Sea and neighboring regions, Alaska, 1910–2010

This report presents data on the approximate locations and methods of discovery of 392 polar bear ( Ursus maritimus ) maternal dens found in the Beaufort Sea and neighboring regions between 1910 and 2010 that are archived by the U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska. A description of data collection methods, biases associated with collection method, primary time periods, and spatial resolution are provided. Polar bears in the Beaufort Sea and nearby regions den on both the sea ice and on land. Standardized VHF surveys and satellite radio telemetry data provide a general understanding of where polar bears have denned in this region over the past 3 decades. Den observations made during other research activities and anecdotal reports from other government agencies, coastal residents, and industry personnel also are reported. Data on past polar bear maternal den locations are provided to inform the public and to provide information for natural resource agencies in planning activities to avoid or minimize interference with polar bear maternity dens.

Alaska↗