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Eric Regehr

Principal Quantitative Ecologist





Department Affiliation

Polar Science Center


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

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


2000-present and while at APL-UW

A demographic survey of the Davis Strait polar bear subpopulation using physical and genetic capture-recapture-recovery sampling

Dunham, K.D., M.G. Dyck, J.V. Ware, A.E. Derocher, E.V. Regehr, H.L. Stern, G.B. Stenson, and D.N. Koons, "A demographic survey of the Davis Strait polar bear subpopulation using physical and genetic capture-recapture-recovery sampling," Mar. Mam. Sci., EOR, doi:10.1111/mms.13107, 2024.

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14 Feb 2024

Conducting assessments to understand the effects of changing environmental conditions on polar bear (Ursus maritimus) demography has become increasingly important to inform management and conservation. Here, we combined physical (2005–2007) and genetic (2017–2018) mark-recapture with harvest recovery data (2005–2018) to estimate demographic rates of the Davis Strait polar bear subpopulation and examine the possible effects of climate, dynamic ice habitat, and prey resources on survival. Large sample sizes (e.g., 2,513 marked animals) allowed us to estimate temporal variation in annual survival rates using multistate mark-recapture-recovery models. We did not detect statistically significant effects of climate, ice habitat, and prey during the 13-year study. Estimated total abundance in 2006 was 2,190, credible interval (CRI) [1,954, 2,454] and 1,944, CRI [1,593, 2,366] in 2018. Geometric mean population growth rate (0.99, 95% CRI [0.97, 1.01]) indicated the subpopulation may have declined slightly between 2006 and 2018. However, we did not detect a declining trend in survival or substantial change in reproductive metrics over this period. Given forecasts of major environmental change we emphasize the need to review monitoring programs for this subpopulation.

Demographic response of a high-Arctic polar bear (Ursus martitimus) subpopulation to changes in sea ice and subsistence harvest

Laidre, K.L., T.W. Arnold, E.V. Regehr, S.N. Atkinson, E.W. Born, O. Wiig, N.J. Lunn, M. Dyck, H.L. Stern, S. Stapleton, B. Cohen, and D. Paetkau, "Demographic response of a high-Arctic polar bear (Ursus martitimus) subpopulation to changes in sea ice and subsistence harvest," Endanger. Species Res., 51, 73-81, doi:10.3354/esr01239, 2023.

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25 May 2023

Climate change is a long-term threat to polar bears. However, sea-ice loss is hypothesized to provide transient benefits in high latitudes, where thick multiyear ice historically limited biological productivity and seal abundance. We used joint live-recapture and dead-recovery mark-recapture models to analyze data for one of the most northerly polar bear subpopulations, Kane Basin. The data consisted of 277 initial live captures and genetic identifications (1992–1997 = 150, 2012–-2014 = 127), 89 recaptures or re-identifications (1992–1997 = 53, 2012–2014 = 36), and 24 harvest returns of research-marked bears during 1992–2014. We estimated mean annual abundance of 357 bears (95% CI: 221–493) for 2013–2014. This suggests a likely increase relative to our estimate of 224 (95% CI: 145–303) bears in the mid-1990s and relative to a previously published estimate of 164 (95% CI: 94–234) bears in the mid-1990s that used some of the same data. This is also supported by an apparent increase in the density of bears in eastern Kane Basin during 2012–2014. Estimates of total survival for females ≥3 yr old (mean ± SE: 0.95 ± 0.04) and their dependent offspring were similar to previous estimates from the 1990s, and estimates of unharvested survival for females ≥3 yr (0.96 ± 0.04) appear sufficient for positive population growth. Estimates of total survival were lower for males ≥3 yr (0.87 ± 0.06). We documented a reduction in mortality associated with subsistence harvest, likely attributable to implementation of a harvest quota by Greenland in 2006. Our findings, together with evidence for increased range sizes, improved body condition for all sex and age classes, and stable reproductive metrics, show that this small high-Arctic polar bear subpopulation remains productive and healthy. These benefits are likely temporary given predictions for continued climate change.

Using visual observations to compare the behavior of previously immobilized and non-immobilized wild polar bears

Stirling, I., E.V. Regehr, C. Spencer, L.E. Burns, and K.L. Laidre, "Using visual observations to compare the behavior of previously immobilized and non-immobilized wild polar bears," Arctic, 75, 398-412, doi:10.14430/arctic76118, 2022.

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1 Dec 2022

During 17 field seasons between 1973 and 1999, we conducted a long-term study of the behavior of undisturbed wild polar bears in Radstock Bay, southwest Devon Island, Nunavut. In a subset of 11 seasons (6 spring and 5 summer) between 1975 and 1997, we used three different drug combinations to chemically immobilize a small number of adult and subadult polar bears on an opportunistic basis and applied a temporary dye mark so that individual bears could be visually reidentified. We then used multinomial logistic regression to compare the behavior of 35 previously immobilized bears of five different demographic classes (sex, age, and reproductive status) to the behavior of non-immobilized bears of the same demographic classes in the same years and seasons. During the first two days after immobilization, bears slept significantly more and spent less time hunting than did bears that had not been immobilized. However, previously immobilized bears returned to the same behavioral patterns and proportion of total time spent hunting as non-immobilized bears within two days and no further negative behavioral effects were detected in the following 21 d. We visually confirmed successful hunting by three adult bears within 0.4 to 2.1 d of being immobilized, all of which went on to make additional kills within the following 24 h. The return to normal behavior patterns, including the ability to hunt successfully, within 48 h of immobilization appears consistent with the hypothesis that polar bears do not experience longer-term behavioral effects following brief chemical immobilization for conservation and management purposes.

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In The News

Polar bears of the past survived warm periods. What does that mean for the future?

Anchorage Daily News, Ned Rozell

A small population of polar bears living off Greenland and Arctic Canada increased by 1.6 times when comparing numbers from the 1990s to 2013 and 2014. Lighter sea ice might have benefited the animals because sunshine penetrates thinner ice better, which stimulates small living things. That means more food for seals, the main food of polar bears.

3 Jun 2023

UW polar bear expert appears in BBC-produced film about the Arctic

UW News, Hannah Hickey

A new production, "Arctic: Our Frozen Planet," narrated by Benedict Cumberbatch, screens May 25 and 27 at the Pacific Science Center in Seattle. Eric Regehr, a researcher at the UW Applied Physics Laboratory, appears in the film doing fieldwork on Wrangel Island, an island off the northeast coast of Russia that is home to the world’s highest concentration of polar bears.

23 May 2023

Why Russia's war in Ukraine is bad news for polar bears, too

The Washington Post, Dino Grandoni

The invasion is first and foremost a human tragedy, but it is also dire for wildlife, stalling scientific work on polar bears and other wildlife threatened with extinction. Sanctions and other policies have chilled scientific collaboration between American and Russian biologists, leading to nixed research trips, canceled conservation work, restricted funding and uncollected data related to imperiled species at risk of disappearing in the coming decades without human help.

15 Apr 2023

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