Featured Research

from universities, journals, and other organizations

Goose Eggs May Help Polar Bears Weather Climate Change

Date:
December 16, 2008
Source:
American Museum of Natural History
Summary:
Polar bears -- especially the marginal individuals like some sub-adult males -- could adapt to changes in ice and the ability to hunt seals by eating snow goose eggs. According to new calculations, bear movement should coordinate more and more with nesting as the Arctic warms, especially near Hudson Bay.

May switch to eggs: sub-adult male polar bear near Churhchill, Manitoba, Canada.
Credit: Patricia Rockwell

As polar bears adapt to a warming Arctic—a frozen seascape that cleaves earlier each spring—they may find relief in an unlikely source: snow goose eggs. New calculations show that changes in the timing of sea-ice breakup and of snow goose nesting near the western Hudson Bay could provide at least some polar bears with an alternative source of food. This new analysis appears in Polar Biology.

"Over 40 years, six subadult male bears were seen among snow goose nests, and four of them were sighted after the year 2000," says Robert Rockwell, a research associate in Ornithology at the American Museum of Natural History and a Professor of Biology at City College at City University of New York. "I've seen a subadult male eat eider duck eggs whole or press its nose against the shell, break it, and eat the contents. This is similar to a different research group's observations of polar bears eating Barnacle Goose eggs on Svalbard, an island near Norway."

Polar bears, Ursus maritimus, are listed as a threatened species under the United States' Endangered Species Act and are classified as "vulnerable with declining populations" under IUCN's Red List. Polar bears' habitat rings the Arctic south of 88˚ latitude. Most of this area is sea ice from which bears hunt seals, although the breakup of sea ice over the summer forces some bears to move north, to pack ice, or onto land. More often, it is subadult males that are pushed to these less ideal conditions, where they live, in part, off stored fat reserves.

When bears switch to the tundra in some areas, they may enter the nesting grounds of snow geese. Goose eggs and developing embryos are a highly nutritious source of food to opportunistic foragers. Although geese populations were in decline in the early 1900s, the population rebounded and expanded. There are now too many geese for the Arctic to support in the summer, mainly because their over-wintering habitat has increased to cover the northern plains, where they eat waste corn and forage in rice fields.

Polar bear and snow geese populations come into contact in the Hudson Bay. Here, some bears routinely live on land for 4-5 months of the year, subsisting on fat reserves. The new research shows that the effects of climate change will bring additional sources of food as the movement of both populations begins earlier each spring. Rockwell and his graduate student, Linda Gormezano, calculated that the rate of change in ice breakup is, on average, 0.72 days earlier each year, and that hatching time is also moving forward by 0.16 days each year. Current trends indicate that the arrival of polar bears will overlap the mean hatching period in 3.6 years, and egg consumption could become a routine, reliable option. At this point, a bear would need to consume the eggs of 43 nests to replace the energy gained from the average day of hunting seals. But within a decade, because timing changes would put bears in contact with even more nests with younger embryos (younger embryos are more nutritious), a bear would only need to consume the eggs of 34 nests to get the same amount of energy.

"Polar bears went through the Eemian 125,000 years ago, when sea level was 4-6 meters higher than it is now and trees lived above the Arctic Circle. They've been through warming before," says Rockwell. "I just read a piece in Natural History with a quote from Ilkoo Angutikjuak that sums this up: 'If the changes continue…the animals will adapt. I've heard that because they depend on sea ice, polar bears will go extinct, but I don't believe it…Polar bears might get skinnier and some might die, but I don't think they will go extinct.'"

Rockwell and Gormezano authored this research article, currently available in the early online version of Polar Biology. Research was funded by the Hudson Bay Project and the American Museum of Natural History.


Story Source:

The above story is based on materials provided by American Museum of Natural History. Note: Materials may be edited for content and length.


Cite This Page:

American Museum of Natural History. "Goose Eggs May Help Polar Bears Weather Climate Change." ScienceDaily. ScienceDaily, 16 December 2008. <www.sciencedaily.com/releases/2008/12/081215111303.htm>.
American Museum of Natural History. (2008, December 16). Goose Eggs May Help Polar Bears Weather Climate Change. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2008/12/081215111303.htm
American Museum of Natural History. "Goose Eggs May Help Polar Bears Weather Climate Change." ScienceDaily. www.sciencedaily.com/releases/2008/12/081215111303.htm (accessed April 20, 2014).

Share This



More Earth & Climate News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drought Concerns May Hurt Lake Tourism

Drought Concerns May Hurt Lake Tourism

AP (Apr. 18, 2014) Operators of recreational businesses on western reservoirs worry that ongoing drought concerns will keep boaters and other visitors from flocking to the popular summer attractions. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Ark. Man Finds 6-Carat Diamond At State Park

Ark. Man Finds 6-Carat Diamond At State Park

Newsy (Apr. 18, 2014) An Arkansas man has found a nearly 6.2-carat diamond, which he dubbed "The Limitless Diamond," at the Crater of Diamonds State Park. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins