Polar Bears International

Our Impact

Field Research

Western Hudson Bay Dens

Most female polar bears dig snow dens to give birth, but the bears in the Western Hudson Bay population, which is farther to the south, choose dens in the peat banks along rivers. But that area is drier now, due to climate change, and more prone to fires caused by lightning strikes. What effect will this have on the bears?

Wrangel Island

For more than a decade, PBI funded Dr. Nikita Ovsyanikov's polar-bear research on Russia's Wrangel Island, where he lived and worked among the great white bears, observing social behavior. He also monitored their health and condition, along with changing sea-ice coverage.

Whisker Pattern Study

How do scientists tell polar bears apart? In the past, scientists traditionally relied on capture-recapture efforts to identify individual bears. But a PBI-funded study by Dr. Jane Waterman confirmed that polar bears' whisker-spot patterns can also provide reliable IDs—especially for field work conducted close to the bears.

The method is simple:

  • Take a digital photo of the polar bear's profile, ideally from less than 50 meters away.
  • Super-impose a grid over the image to map out the whisker-spot pattern.
  • Use that pattern to ID the bear.

Just like fingerprints. Waterman and her team found that each polar bear has a unique whisker-spot pattern that can confirm the bear's identity. This quick and easy, non-intrusive method is especially well suited for behavior and population studies in places like Churchill where polar bears gather.

Captive Research and Well Being

Milk Composition Study

Until recently, concerns about bone fractures in some hand-reared cubs raised concerns about what to feed them. In the wild, adult polar bears feed primarily on seals, feasting solely on blubber when hunting is good. This high-fat diet helps protect polar bears from the cold and enables mother bears to nourish their cubs with thick, rich milk with 30% fat.

But a high-fat formula alone doesn't provide proper nourishment, as some zoos have found. Make a mistake, and cubs have problems with bone development.

Gail Hedberg, a veterinary technician and neonatal care specialist with the San Francisco Zoo, conducted a PBI-funded study that provides answers and sets the industry standard.

To determine the nutritional needs of hand-reared cubs, Hedberg obtained samples of milk from wild lactating polar bears. She and her team then analyzed the samples, not only for fat composition and fatty acids, but also for carbohydrates, fat-soluble vitamins, protein, and amino acids.

The study results are now helping cubs worldwide. The team's paper was published in Zoo Biology and is available online.

Stereotypic Behavior

Three years. 20 zoos. 55 polar bears.

This ground-breaking study was the first to take a comprehensive look at repetitive behavior in polar bears living in zoos—and to document ways to change it. The results? Some zoos have reduced pacing and other stereotypic behavior by 95%. 

Dr. David Shepherdson, a research scientist at the Oregon Zoo in Portland and a well-known animal behaviorist, conducted the study for PBI. He examined:

  • Factors that lead polar bears to pace or swim in repetitive patterns.
  • The effects of exhibit designs.
  • Enrichment items that encourage good health and reduce stress.

Shepherdson monitored the bears for three years. He measured blood-cortisol levels to gauge stress responses. He also assessed the behavior and temperament of each bear.

Want to learn more? We've gathered his key findings here.

Estrous Cycles

How many estrous cycles occur in polar bears? How long is each cycle? And why should we care?

Dr. Tom Spady, a reproductive physiologist, studied the polar bear's breeding cycle as part of a team working at the San Diego Zoo. His findings are important because we may be left with remnant populations of wild bears as the sea ice continues to shrink. A boost of genetic diversity from zoo bears may help these survivors repopulate the Arctic if the sea ice returns.

In the meantime, the knowledge gained is helping zoos:

  • Notice if a zoo bear has a problem, since ovarian cycles are an early indicator of reproductive health.
  • Develop effective birth control for polar bears in zoos.
  • Know when to introduce males and females for natural breeding.
  • Know when to separate bears.
  • Apply assisted reproductive techniques more effectively.
  • Notice if a zoo bear has a problem, since ovarian cycles are an early indicator of reproductive health.

The study is yet another example of how research with captive bears may benefit their wild counterparts.

Nutrition Study/Association of Zoos & Aquariums

Polar bears eat mainly seals in the wild, but what they should eat in zoos? When PBI hosted the International Polar Bear Husbandry Conference in 2004, we quickly realized that members of the zoo community had a number of questions related to diet.

Blubber or carrots? To fill this need, we brought together nutrition experts from zoos, led by Barbara Lintzenich (Cincinnati Zoo), chair of the American Zoo Association's Nutrition Advisory Group and team director of the project. They produced a comprehensive manual on the nutritional needs of captive polar bears. The 66-page document covers:

  • Dietary needs of polar bears in zoos.
  • Feeding methods that provide psychological stimulation.
  • Sample menus.

International Polar Bear Husbandry Conference

PBI organized and hosted this international conference in 2004 as a way to bring together experts from the zoo and wild bear communities. Such a cross-disciplinary gathering had never been held before, for any species.

We organized the conference so the two groups could:

  • Meet and interact with each other.
  • Share information and points of view.
  • Discuss research needs and find ways to help each other.

It's all about polar bears. More than 50 speakers from around the world helped stimulate discussions. The various captive-wild polar-bear research initiatives PBI has since funded are a direct result of the conference. 

Polar Bears Comprehensive PDF