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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

Modeling movements improves capture-recapture estimates for mobile species with sparse data: Polar bears (Ursus maritimus) in Viscount Melville Sound

Regehr, E.V., S. Baryluk, J. Boulanger, M. Branigan, F. d'Eon-Eggertson, J. Pongracz, A. Thom, and E.S. Richardson, "Modeling movements improves capture-recapture estimates for mobile species with sparse data: Polar bears (Ursus maritimus) in Viscount Melville Sound," Popul. Ecol., EOR, doi:10.1002/1438-390X.12198, 2024.

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11 Oct 2024

Wildlife management requires estimates of demographic parameters that are difficult to obtain for mobile species at low densities. Biased parameter estimates often result from capture-recapture (CR) studies due to small sample sizes and unequal recapture probabilities, the latter of which can be caused by animal movements with respect to the sampling area. We developed a multistate CR model designed to minimize biases by including multiple data types (capture, harvest, natural mortality, and telemetry) and accounting for temporary emigration. We applied the model to data collected intensively from 2012 to 2014, and intermittently since the 1970s, for the Viscount Melville (VM) subpopulation of polar bears (Ursus maritimus) in the Canadian Arctic. The number of bears within the VM subpopulation boundary likely increased from an average of 145 (Bayesian 95% credible interval [CRI] [109, 221]) in 1989–1992 to 235 (95% CRI [148, 569]) in 2012–2014. Survival probability increased for all sex and age classes except adult females, for which estimates declined due to unknown reasons. Polar bear movements exhibited Markovian dependence with approximately 28% of the subpopulation located outside of the sampling area each spring. This contributed to inaccurate parameter estimates when using a simpler, single-state CR model that only included capture data. Although the interpretation of demographic status was complicated by statistical uncertainty and changes in study design, our findings suggest that—as of 2014—the VM polar bear subpopulation had likely recovered from an earlier period of overharvest, was stable, and had not exhibited detectable negative effects of climate warming.

Nursing behavior of wild polar bears in the Canadian High Arctic

Stirling, I., L.E. Burns, E.V. Regehr, K.L. Laidre, and C. Spencer, "Nursing behavior of wild polar bears in the Canadian High Arctic," Can. J. Zool., 102, 663-672, doi:10.1139/cjz-2024-0001, 2024.

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19 Jul 2024

During 17 spring and summer field seasons between 1973 and 1999, we documented 220 bouts of nursing by dependent polar bear (Ursus maritimus Phipps, 1774) cubs at Radstock Bay, Nunavut, Canada. The overall mean duration of nursing bouts for cubs-of-the-year (COY) and yearlings (YRLG) litters was 7.1 min (standard deviation (SD) = 3.3, range = 1–23). Mean nursing bout durations of one- and two-cub litters of COY and YRLG in spring and summer seasons ranged from 6.09 to 7.78 min and from 5.00 to 9.18 min, respectively. The overall mean duration of inter-nursing intervals for COY and YRLG litters was 5.7 h (SD = 4.9, range = 0.0–35.0). The mean inter-nursing interval for one-cub litters was 6.4 h (SD = 4.6, range = 0.0–20.2) and for two-cub litters was 5.1 h (SD = 5.1, range = 0.0–35.0). We found no evidence for effects of season or cub age class on nursing behavior. We found weak evidence that two-cub litters nurse slightly longer than one-cub litters, potentially reflecting reduced nursing efficiency due to sibling rivalry. There was neither evidence for diel patterns in nursing behavior nor a detectable relationship between the cessation of nursing and the onset of hunting or sleeping by the adult female.

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., 40, doi:10.1111/mms.13107, 2024.

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1 Jul 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.

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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

More News Items

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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