Current Global Change Projects

Project Title: Polar Bear Survival in a Vanishing Sea Ice Environment
Principal Investigator: Steve Amstrup
Co-PI’s: *George M. Durner - Primary Contact (USGS), David C. Douglas (USGS), Geoff York (USGS)

Introduction

Polar bears (Ursus maritimus) in northern Alaska are dependent on sea ice for all aspects of their life history.  Widespread alteration and loss of ice habitats could impose unprecedented pressure on their reproductive and foraging success.  Evidence indicates that global climate patterns are changing.  In the Arctic this has resulted in a decrease in sea ice extent and thickness.  The relatively shallow waters over the continental shelf are important foraging habitat for polar bears.  This habitat has become unavailable during the late summer and early autumn because of increasing temporal and spatial extent of summer ice melt.  Bears are forced into areas, either on shore or beyond the continental shelf, where they cannot hunt for their preferred prey.  If the delayed freeze-up in autumn does reduce overall hunting success, bears will enter the winter months in poor body condition.  This decrease in body condition may result in decreased reproductive output, and lower survival of young.  Due to their requirement for body reserves sufficient to give birth to and nurture new-born young throughout the Arctic winter, this is especially important for pregnant polar bears.

This project proposes to examine polar bear habitat use, reproduction and survival relative to a changing sea ice environment.  Specially, we will address the following questions:

1. How is polar bear habitat availability and quality influenced by ongoing climate changes and how do polar bears respond?
   
   
2. How do polar bear responses climate-induced changes to the sea ice environment affect body condition of adults, numbers of and sizes of offspring, survival of offspring to weaning (recruitment) and population age structure?

Polar bears fall under the jurisdiction of the Marine Mammal Protection Act of 1972 and are an integral part of the traditional life styles of indigenous people.  Also, the five nations whose jurisdictions include polar bears have agreed to protect their habitat.  Native communities in Canada and Alaska have an agreement to regulate the harvest of polar bears and to protect polar bears in dens and females with cubs.  As the apical species in the Arctic, polar bears may be the first large mammal that shows the effects of climate change.  This, with an abundance of baseline data on survival and recruitment, denning ecology, distribution, population bounds, and habitat use, make polar bears an excellent species to study in order to understand the ecological effects of climate change in the Arctic.  This research addresses the 5 year goal of the USGS Global Change Research Program by determining the relative sensitivity of a biological resource (polar bears) and an important geographical region of the United States (the Alaskan Beaufort Sea) to climate change. The products of the USGS GCC Polar Bear Project are providing valuable foundations for current USGS efforts to expand and assemble scientific information that will be used by the USFWS in deciding whether the polar bear should be listed as threatened under the ESA.

Contact Information:

Address: 1011 East Tudor Road, Anchorage, AK  99503
Telephone/fax number: (907) 786-3366/ (907) 786-3636
Email: gdurner@usgs.gov