Resale or republication not permitted without written consent of the publisherAdult female and young Pacific walruses Odobenus rosmarus divergens resting on sea ice during summer in the Chukchi Sea. Walrus at front left has a radio tag attached.

Understanding causes of polar bear (Ursus maritimus) attacks on humans is critical to ensuring both human safety and polar bear conservation. Although considerable attention has been focused on understanding black (U. americanus) and grizzly (U. arctos) bear conflicts with humans, there have been few attempts to systematically collect, analyze, and interpret available information on human‐polar bear conflicts across their range. To help fill this knowledge gap, a database was developed (Polar Bear‐Human Information Management System [PBHIMS]) to facilitate the range‐wide collection and analysis of human‐polar bear conflict data. We populated the PBHIMS with data collected throughout the polar bear range, analyzed polar bear attacks on people, and found that reported attacks have been extremely rare. From 1870–2014, we documented 73 attacks by wild polar bears, distributed among the 5 polar bear Range States (Canada, Greenland, Norway, Russia, and United States), which resulted in 20 human fatalities and 63 human injuries. We found that nutritionally stressed adult male polar bears were the most likely to pose threats to human safety. Attacks by adult females were rare, and most were attributed to defense of cubs. We judged that bears acted as a predator in most attacks, and that nearly all attacks involved ≤2 people. Increased concern for both human and bear safety is warranted in light of predictions of increased numbers of nutritionally stressed bears spending longer amounts of time on land near people because of the loss of their sea ice habitat. Improved conflict investigation is needed to collect accurate and relevant data and communicate accurate bear safety messages and mitigation strategies to the public. With better information, people can take proactive measures in polar bear habitat to ensure their safety and prevent conflicts with polar bears. This work represents an important first step towards improving our understanding of factors influencing human‐polar bear conflicts. Continued collection and analysis of range‐wide data on interactions and conflicts will help increase human safety and ensure the conservation of polar bears for future generations. © 2017 The Wildlife Society.

In spring 2006, we conducted a collaborative U.S.–Russia survey to estimate abundance of the Pacific walrus (Odobenus rosmarus divergens). The Bering Sea was partitioned into survey blocks, and a systematic random sample of transects within a subset of the blocks was surveyed with airborne thermal scanners using standard strip‐transect methodology. Counts of walruses in photographed groups were used to model the relation between thermal signatures and the number of walruses in groups, which was used to estimate the number of walruses in groups that were detected by the scanner but not photographed. We also modeled the probability of thermally detecting various‐sized walrus groups to estimate the number of walruses in groups undetected by the scanner. We used data from radio‐tagged walruses to adjust on‐ice estimates to account for walruses in the water during the survey. The estimated area of available habitat averaged 668,000 km2 and the area of surveyed blocks was 318,204 km2. The number of Pacific walruses within the surveyed area was estimated at 129,000 with 95% confidence limits of 55,000–507,000 individuals. Poor weather conditions precluded surveying in other areas; therefore, this value represents the number of Pacific walruses within about half of potential walrus habitat.

Polar bears (Ursus maritimus) are expected to be adversely impacted by a warming Arctic due to melting of the sea‐ice platform from which they hunt ice‐breeding seals. We evaluated the hypothesis that scavenging on stranded large whale carcasses may have facilitated polar bear survival through past interglacial periods during which sea‐ice was limited by analyzing: (1) present‐day scavenging by polar bears on large whale carcasses; (2) energy values of large whale species; and (3) the ability of polar bears, like the brown bears (Ursus arctos) from which they evolved, to quickly store large amounts of lipids and to fast for extended periods. We concluded that scavenging on large whale carcasses likely facilitated survival of polar bears in past interglacial periods when access to seals was reduced. In a future, ice‐impoverished Arctic, whale carcasses are less likely to provide nutritional refuge for polar bears because overharvesting by humans has greatly reduced large whale populations, carcass availability is geographically limited, and climate‐induced sea‐ice loss is projected to occur at a more rapid pace than polar bears have experienced at any previous time in their evolutionary history.