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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

Integrated population modeling provides the first empirical estimates of vital rates and abundance for polar bears in the Chukchi Sea

Regehr, E.V., N.J. Hostetter, R.R. Wilson, K.D. Rode, M. St. Martin, and S.J. Converse, "Integrated population modeling provides the first empirical estimates of vital rates and abundance for polar bears in the Chukchi Sea," Sci. Rep., 8, 16780, doi:10.1038/s41598-018-34824-7, 2018.

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14 Nov 2018

Large carnivores are imperiled globally, and characteristics making them vulnerable to extinction (e.g., low densities and expansive ranges) also make it difficult to estimate demographic parameters needed for management. Here we develop an integrated population model to analyze capture-recapture, radiotelemetry, and count data for the Chukchi Sea subpopulation of polar bears (Ursus maritimus), 2008–2016. Our model addressed several challenges in capture-recapture studies for polar bears by including a multievent structure reflecting location and life history states, while accommodating state uncertainty. Female breeding probability was 0.83 (95% credible interval [CRI] = 0.71–0.90), with litter sizes of 2.18 (95% CRI = 1.71–2.82) for age-zero and 1.61 (95% CRI = 1.46–1.80) for age-one cubs. Total adult survival was 0.90 (95% CRI = 0.86–0.92) for females and 0.89 (95% CRI = 0.83–0.93) for males. Spring on-ice densities west of Alaska were 0.0030 bears/km2 (95% CRI = 0.0016–0.0060), similar to 1980s-era density estimates although methodological differences complicate comparison. Abundance of the Chukchi Sea subpopulation, derived by extrapolating density from the study area using a spatially-explicit habitat metric, was 2,937 bears (95% CRI = 1,552–5,944). Our findings are consistent with other lines of evidence suggesting the Chukchi Sea subpopulation has been productive in recent years, although it is uncertain how long this will continue given sea-ice loss due to climate change.

Range contraction and increasing isolation of a polar bear subpopulation in an era of sea‐ice loss

Laidre, K.L., E.W. Born, S.N. Atkinson, Ø. Wiig, L.W. Andersen, N.J. Lunn, M. Dyck, E.V. Regehr, R. McGovern, and P. Heagerty, "Range contraction and increasing isolation of a polar bear subpopulation in an era of sea‐ice loss," Ecol. Evol., 8, 2062-2075, doi:10.1002/ece3.3809, 2018.

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1 Feb 2018

Climate change is expected to result in range shifts and habitat fragmentation for many species. In the Arctic, loss of sea ice will reduce barriers to dispersal or eliminate movement corridors, resulting in increased connectivity or geographic isolation with sweeping implications for conservation. We used satellite telemetry, data from individually marked animals (research and harvest), and microsatellite genetic data to examine changes in geographic range, emigration, and interpopulation connectivity of the Baffin Bay (BB) polar bear (Ursus maritimus) subpopulation over a 25‐year period of sea‐ice loss. Satellite telemetry collected from n = 43 (1991–1995) and 38 (2009–2015) adult females revealed a significant contraction in subpopulation range size (95% bivariate normal kernel range) in most months and seasons, with the most marked reduction being a 70% decline in summer from 716,000 km2 (SE 58,000) to 211,000 km2 (SE 23,000) (p < .001). Between the 1990s and 2000s, there was a significant shift northward during the on‐ice seasons (2.6° shift in winter median latitude, 1.1° shift in spring median latitude) and a significant range contraction in the ice‐free summers. Bears in the 2000s were less likely to leave BB, with significant reductions in the numbers of bears moving into Davis Strait (DS) in winter and Lancaster Sound (LS) in summer. Harvest recoveries suggested both short and long‐term fidelity to BB remained high over both periods (83–99% of marked bears remained in BB). Genetic analyses using eight polymorphic microsatellites confirmed a previously documented differentiation between BB, DS, and LS; yet weakly differentiated BB from Kane Basin (KB) for the first time. Our results provide the first multiple lines of evidence for an increasingly geographically and functionally isolated subpopulation of polar bears in the context of long‐term sea‐ice loss. This may be indicative of future patterns for other polar bear subpopulations under climate change.

Relative influences of climate change and human activity on the onshore distribution of polar bears

Wilson, R.R., E.V. Regehr, M. St. Martin, T.C. Atwood, E. Peacock, S. Miller, and G. Divoky, "Relative influences of climate change and human activity on the onshore distribution of polar bears," Biol. Conserv., 214, 288-294, doi:10.1016/j.biocon.2017.08.005, 2017.

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1 Oct 2017

Climate change is altering habitat for many species, leading to shifts in distributions that can increase levels of human–wildlife conflict. To develop effective strategies for minimizing human–wildlife conflict, we must understand the relative influences that climate change and other factors have on wildlife distributions. Polar bears (Ursus maritimus) are increasingly using land during summer and autumn due to sea ice loss, leading to higher incidents of conflict and concerns for human safety. We sought to understand the relative influence of sea ice conditions, onshore habitat characteristics, and human-provisioned food attractants on the distribution and abundance of polar bears while on shore. We also wanted to determine how mitigation measures might reduce human–polar bear conflict associated with an anthropogenic food source. We built a Bayesian hierarchical model based on 14 years of aerial survey data to estimate the weekly number and distribution of polar bears on the coast of northern Alaska in autumn. We then used the model to predict how effective two management options for handling subsistence-harvested whale remains in the community of Kaktovik, Alaska might be. The distribution of bears on shore was most strongly influenced by the presence of whale carcasses and to a lesser extent sea ice and onshore habitat conditions. The numbers of bears on shore were related to sea ice conditions. The two management strategies for handling the whale carcasses reduced the estimated number of bears near Kaktovik by > 75%. By considering multiple factors associated with the onshore distribution and abundance of polar bears we discerned what role human activities played in where bears occur and how successful efforts to manage the whale carcasses might be for reducing human–polar bear conflict.

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In The News

New study says Chukchi polar bears are healthy despite sea ice loss — for now

Alaska Public Media, Ravenna Koenig

The very first tally of the Chukchi Sea polar bears has just been published, and here’s the big takeaway: Despite a decline in their sea ice habitat, for now the bears are doing well.

20 Nov 2018

Study finds healthy group of polar bears in sea near Alaska

Associated Press, Dan Joling

The first formal count of polar bears in waters between the United States and Russia indicates they’re doing better than some of their cousins elsewhere.

15 Nov 2018

First tally of U.S.–Russia polar bears finds a healthy population

UW News, Hannah Hickey

Not all polar bears are in the same dire situation due to retreating sea ice, at least not right now. Off the western coast of Alaska, the Chukchi Sea is rich in marine life, but the number of polar bears in the area had never been counted. The first formal study of this population suggests that it’s been healthy and relatively abundant in recent years, numbering about 3,000 animals.

14 Nov 2018

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