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Kristin Laidre

Principal Oceanographer

Assistant Professor, Fisheries





Department Affiliation

Polar Science Center


B.S. Zoology, University of Washington - Seattle, 1999

Ph.D. Aquatic & Fishery Sciences, University of Washington - Seattle, 2003

Kristin Laidre's Website



2000-present and while at APL-UW

Grounded icebergs as maternity denning habitat for polar bears (Ursus maritimus) in North and Northeast Greenland

Laidre, K.L., and I. Stirling, "Grounded icebergs as maternity denning habitat for polar bears (Ursus maritimus) in North and Northeast Greenland," Polar Biol., 43, 937-943, doi:10.1007/s00300-020-02695-2, 2020.

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1 Jul 2020

This study provides the first documentation of polar bear (Ursus maritimus) maternity denning in snowdrifts around icebergs frozen into the fast ice or grounded on the seafloor. Based on six den observations in north and northeast Greenland during spring surveys in 2018 and 2019 (109 flight hours), together with observations of 20 adult females with 35 cubs of the year (COYs) in adjacent sea ice, we hypothesize that the use of snowdrifts around icebergs for maternity denning is an established behavior in the region and not a random event. Factors influencing maternity denning in snowdrifts around icebergs may include limited suitable drifts on the nearby terrestrial polar desert due to low precipitation, the presence of suitable wind-blown snow banks regardless of the direction of autumn storm winds, cold and stable habitat throughout the winter denning period, and access to ringed seal (Pusa hispida) pupping habitat in the nearby Northeast Water polynya. This type of maternity denning habitat is only available in glaciated regions of the Arctic where marine-terminating glaciers deposit mélange large enough to become grounded offshore and remain in place for months or years. This habitat may become less stable or disappear with long-term climate warming.

Variability in fin whale (Balaenoptera physalus) occurrence in the Bering Strait and southern Chukchi Sea in relation to environmental factors

Escajeda, E., K.M. Stafford, R.A. Woodgate, K.L. Laidre, "Variability in fin whale (Balaenoptera physalus) occurrence in the Bering Strait and southern Chukchi Sea in relation to environmental factors," Deep Sea Res. II, EOR, doi:0.1016/j.dsr2.2020.104782, 2020.

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4 May 2020

Fin whales (Balaenoptera physalus) are common summer visitors to the Pacific Arctic, migrating through the Bering Strait and into the southern Chukchi Sea to feed on seasonally-abundant prey. The abundance and distribution of fin whales in the Chukchi Sea varies from year-to-year, possibly reflecting fluctuating environmental conditions. We hypothesized that fin whale calls were most likely to be detected in years and at sites where productive water masses were present, indicated by low temperatures and high salinities, and where strong northward water and wind velocities, resulting in increased prey advection, were prevalent. Using acoustic recordings from three moored hydrophones in the Bering Strait region from 2009–2015, we identified fin whale calls during the open-water season (July–November) and investigated potential environmental drivers of interannual variability in fin whale presence. We examined near-surface and near-bottom temperatures (T) and salinities (S), wind and water velocities through the strait, water mass presence as estimated using published T/S boundaries, and satellite-derived sea surface temperatures and sea-ice concentrations. Our results show significant interannual variability in the acoustic presence of fin whales with the greatest detections of calls in years with contrasting environmental conditions (2012 and 2015). Colder temperatures, lower salinities, slower water velocities, and weak southward winds prevailed in 2012 while warmer temperatures, higher salinities, faster water velocities, and moderate southward winds prevailed in 2015. Most detections (96%) were recorded at the mooring site nearest the confluence of the nutrient-rich Anadyr and Bering Shelf water masses, ~35 km north of Bering Strait, indicating that productive water masses may influence the occurrence of fin whales. The disparity in environmental conditions between 2012 and 2015 suggests there may be multiple combinations of environmental factors or other unexamined variables that draw fin whales into the Pacific Arctic.

The ecological and behavioral significance of short-term food caching in polar bears (Ursus maritimus)

Stirling, I., K.L. Laidre, A.E. Derocher, and R. Van Meurs, "The ecological and behavioral significance of short-term food caching in polar bears (Ursus maritimus)," Arctic Sci., 6, 41-52, doi:10.1139/as-2019-0008, 2020.

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1 Mar 2020

The paucity of observations of wild polar bears (Ursus maritimus) caching of food (including hoarding, i.e., burying and remaining with a kill for up to a few days) has led to the conclusion that such behavior does not occur or is negligible in this species. We document 19 observations of short-term hoarding by polar bears between 1973 and 2018 in Svalbard, Greenland, and Canada. Short-term hoarding appears to be influenced by size of the kill and its remaining energetic value after the first meal has been consumed. Fat and meat from smaller seals, such as pup or yearling ringed seals (Pusa hispida), are largely devoured immediately, leaving little to hoard. Carcasses of adult ringed seals, harp seals (Pagophilus groenlandicus), and bearded seals (Erignathus barbatus) may be covered with snow to reduce the chance of kleptoparasitism by another bear or other scavengers visually detecting a dark spot on the ice, while the hoarding bear lies nearby. Hoarding of other species, such as beluga (Delphinapterus leucas) (calves or parts) or other polar bears, appears opportunistic. We review differences in caching, including short-term hoarding behavior between polar bears and brown bears (U. arctos), and hypothesize about factors that may have influenced their evolution.

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In The News

Polar bears are getting thinner and having fewer cubs

CNN, Scottie Andrew

The impact of the climate crisis is becoming more and more obvious to humans and their animal neighbors. But among all species, polar bears might be some of the hardest hit.

14 Feb 2020

Polar bears in Baffin Bay skinnier, having fewer cubs due to less sea ice

UW News, Hannah Hickey

Polar bears are spending more time on land than they did in the 1990s due to reduced sea ice, new University of Washington-led research shows. Bears in Baffin Bay are getting thinner and adult females are having fewer cubs than when sea ice was more available.

12 Feb 2020

Polar bears struggle as sea ice declines

NASA Earth Observatory, Kasha Patel

A new study shows that polar bears are spending less time on sea ice, leading them to fast longer, become thinner and have fewer cubs.

4 Feb 2020

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