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Eric Regehr

Principal Quantitative Ecologist

Email

eregehr@apl.washington.edu

Phone

206-685-3512

Department Affiliation

Polar Science Center

Education

B.S. Chemical Engineering, University of Kansas, 1998

Ph.D. Zoology & Physiology, University of Wyoming - Laramie, 2009

Publications

2000-present and while at APL-UW

Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions

Laidre, K.L. and 18 others including E.V. Regehr, B. Cohen, and H.L. Stern, "Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions," Science, 376, 1333-1338, doi:10.1126/science.abk2793, 2022.

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17 Jun 2022

Polar bears are susceptible to climate warming because of their dependence on sea ice, which is declining rapidly. We present the first evidence for a genetically distinct and functionally isolated group of polar bears in Southeast Greenland. These bears occupy sea-ice conditions resembling those projected for the High Arctic in the late 21st century, with an annual ice-free period that is >100 days longer than the estimated fasting threshold for the species. Whereas polar bears in most of the Arctic depend on annual sea ice to catch seals, Southeast Greenland bears have a year-round hunting platform in the form of freshwater glacial mélange. This suggests that marine-terminating glaciers, although of limited availability, may serve as previously unrecognized climate refugia. Conservation of Southeast Greenland polar bears, which meet criteria for recognition as the world’s 20th polar bear subpopulation, is necessary to preserve the genetic diversity and evolutionary potential of the species.

Modeling spatiotemporal abundance and movement dynamics using an integrated spatial capture–recapture movement model

Hostetter, N.J., E.V. Regehr, R.R. Wilson, J.A. Royle, and S.J. Converse, "Modeling spatiotemporal abundance and movement dynamics using an integrated spatial capture–recapture movement model," Ecology, EOR, doi:10.1002/ecy.3772, 2022.

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28 May 2022

Animal movement is a fundamental ecological process affecting the survival and reproduction of individuals, the structure of populations, and the dynamics of communities. Methods to quantify animal movement and spatiotemporal abundances, however, are generally separate and therefore omit linkages between individual-level and population-level processes. We describe an integrated spatial capture–recapture (SCR) movement model to jointly estimate (1) the number and distribution of individuals in a defined spatial region and (2) movement of those individuals through time. We applied our model to a study of polar bears (Ursus maritimus) in a 28,125 km2 survey area of the eastern Chukchi Sea, USA in 2015 that incorporated capture–recapture and telemetry data. In simulation studies, the model provided unbiased estimates of movement, abundance, and detection parameters using a bivariate normal random walk and correlated random walk movement process. Our case study provided detailed evidence of directional movement persistence for both male and female bears, where individuals regularly traversed areas larger than the survey area during the 36-day study period. Scaling from individual- to population-level inferences, we found that densities varied from <0.75 bears/625 km2 grid cell/day in nearshore cells to 1.6–2.5 bears/grid cell/day for cells surrounded by sea ice. Daily abundance estimates ranged from 53 to 69 bears, with no trend across days. The cumulative number of unique bears that used the survey area increased through time due to movements into and out of the area, resulting in an estimated 171 individuals using the survey area during the study (95% credible interval 124–250). Abundance estimates were similar to a previous multiyear integrated population model using capture–recapture and telemetry data (2008–2016; Regehr et al., Scientific Reports 8:16780, 2018). Overall, the SCR–movement model successfully quantified both individual- and population-level space use, including the effects of landscape characteristics on movement, abundance, and detection, while linking the movement and abundance processes to directly estimate density within a prescribed spatial region and temporal period. Integrated SCR–movement models provide a generalizable approach to incorporate greater movement realism into population dynamics and link movement to emergent properties including spatiotemporal densities and abundances.

Demographic risk assessment for a harvested species threatened by climate change: polar bears in the Chukchi Sea

Regehr, E.V., M.C. Runge, A. Von Duyke, R.R. Wilson, L. Polasek, K.D. Rode, N.J. Hostetter, and S.J. Converse, "Demographic risk assessment for a harvested species threatened by climate change: polar bears in the Chukchi Sea," Ecol. Appl., 31, doi:10.1002/eap.2461, 2021.

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1 Dec 2021

Climate change threatens global biodiversity. Many species vulnerable to climate change are important to humans for nutritional, cultural, and economic reasons. Polar bears Ursus maritimus are threatened by sea-ice loss and represent a subsistence resource for Indigenous people. We applied a novel population modeling-management framework that is based on species life history and accounts for habitat loss to evaluate subsistence harvest for the Chukchi Sea (CS) polar bear subpopulation. Harvest strategies followed a state-dependent approach under which new data were used to update the harvest on a predetermined management interval. We found that a harvest strategy with a starting total harvest rate of 2.7% (~85 bears/yr at current abundance), a 2:1 male-to-female ratio, and a 10-yr management interval would likely maintain subpopulation abundance above maximum net productivity level for the next 35 yr (approximately three polar bear generations), our primary criterion for sustainability. Plausible bounds on starting total harvest rate were 1.7–3.9%, where the range reflects uncertainty due to sampling variation, environmental variation, model selection, and differing levels of risk tolerance. The risk of undesired demographic outcomes (e.g., overharvest) was positively related to harvest rate, management interval, and projected declines in environmental carrying capacity; and negatively related to precision in population data. Results reflect several lines of evidence that the CS subpopulation has been productive in recent years, although it is uncertain how long this will last as sea-ice loss continues. Our methods provide a template for balancing trade-offs among protection, use, research investment, and other factors. Demographic risk assessment and state-dependent management will become increasingly important for harvested species, like polar bears, that exhibit spatiotemporal variation in their response to climate change.

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In The News

'Wholly unexpected': These polar bears can survive with less sea ice

The New York Times, Henry Fountain

The overall threat to the animals from climate change remains, but a new finding suggests that small numbers might survive for longer as the Arctic warms. See related articles on the UW News pinboard.

16 Jun 2022

Newly documented population of polar bears in Southeast Greenland sheds light on the species' future in a warming Arctic

UW News, Hannah Hickey

Scientists have documented a previously unknown subpopulation of polar bears living in Southeast Greenland. The polar bears survive with limited access to sea ice by hunting from freshwater ice that pours into the ocean from Greenland’s glaciers.

16 Jun 2022

'It looks like Iron Curtain 2.' Arctic research with Russia curtailed after Ukraine invasion

Science, Warren Cornwall

The fate of Regehr's annual science expedition to Wrangel Island, which offers a critical window into the fate of thousands of polar bears, is just one sign of how the Russian invasion of Ukraine is curtailing research collaborations all over the globe.

4 Mar 2022

More News Items

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