Featured Research

from universities, journals, and other organizations

Polar Bears Threatened By Hunting Policy Favoring The Killing Of Male Bears

Date:
November 25, 2007
Source:
University of Alberta
Summary:
Policies that encourage hunters to go after male polar bears in order to conserve females, could make it harder for the animals to find mates. Researchers determined there is a critical threshold in the male-to-female ratio. Below it, their model predicts a sudden and rapid collapse in fertilization rates.

Polar bear - Ursus maritimus - on the ice in the Beaufort Sea. New research suggests that current wildlife management practices in Canada could make it harder for polar bears to find mates.
Credit: Courtesy of Mr. Ardo X. Meyer

Policies that encourage hunters to go after male polar bears in order to conserve females, could make it harder for the animals to find mates. University of Alberta researchers determined there is a critical threshold in the male-to-female ratio. Below it, their model predicts a sudden and rapid collapse in fertilization rates.

Harvesting regulations vary around the world, notes PhD student Péter Molnár of the Department of Biological Sciences, the study’s lead author. For example, Canada uses a quota system, permitting some hunting to a predetermined limit, while Norway bans any hunting of polar bears.

Current Canadian management polices encourage hunters to go after male bears in order to conserve females while maximizing the number of bears that may be harvested. But harvesting based on sex selection has reduced the number of males compared to females in polar bear populations across the Canadian Arctic, Molnár says.

Molnár’s work was supervised by Professor Andrew Derocher, a noted polar bear expert, and Professor Mark Lewis, who holds the Canada Research Chair in Mathematical Biology. The study was conducted in collaboration with Dr. Mitchell Taylor from the Government of Nunavut.

The U of A team warns that under certain conditions, this practice of sex-selective harvesting could lead to trouble when it comes to polar bears finding a mate - based on a biological mathematical model they developed, and data from the polar bear population at Lancaster Sound off Cornwallis Island (northwest of Baffin Island) in the High Arctic.

The mathematical model has given the researchers the ability to predict how many male bears are needed in an area compared to the number of female bears that are around, to maintain successful mating.

They determined that there is a critical threshold in the male-to-female ratio. If the sex ratio drops below this threshold, the model predicts a sudden and rapid collapse in fertilization rates. This threshold depends on whether the area has a high-density or low-density bear population.

Each bear population must be evaluated separately, since results will be different depending on the population characteristics of the area. But the U of A scientists can say that in regions with fewer bears travelling a larger area (low-density population), there actually needs to be more males than breeding females to maintain high fertilization rates.

Given this important population threshold, the authors concluded that polar bear populations should be closely monitored and carefully harvested, as severe negative effects could arise either from overharvesting male bears or from population decline.

These findings appeared November 21 in the online edition of the Proceedings of the Royal Society.


Story Source:

The above story is based on materials provided by University of Alberta. Note: Materials may be edited for content and length.


Cite This Page:

University of Alberta. "Polar Bears Threatened By Hunting Policy Favoring The Killing Of Male Bears." ScienceDaily. ScienceDaily, 25 November 2007. <www.sciencedaily.com/releases/2007/11/071123192959.htm>.
University of Alberta. (2007, November 25). Polar Bears Threatened By Hunting Policy Favoring The Killing Of Male Bears. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2007/11/071123192959.htm
University of Alberta. "Polar Bears Threatened By Hunting Policy Favoring The Killing Of Male Bears." ScienceDaily. www.sciencedaily.com/releases/2007/11/071123192959.htm (accessed October 23, 2014).

Share This



More Plants & Animals News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Working Mother DIY: Pumpkin Pom-Pom

Working Mother DIY: Pumpkin Pom-Pom

Working Mother (Oct. 22, 2014) — How to make a pumpkin pom-pom. Video provided by Working Mother
Powered by NewsLook.com
San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) — The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Raw: Bear Cub Strolls Through Oregon Drug Store

Raw: Bear Cub Strolls Through Oregon Drug Store

AP (Oct. 22, 2014) — Shoppers at an Oregon drug store were surprised by a bear cub scurrying down the aisles this past weekend. (Oct. 22) Video provided by AP
Powered by NewsLook.com
Family Pleads for Pet Pig to Stay at Home

Family Pleads for Pet Pig to Stay at Home

AP (Oct. 22, 2014) — The Johnson family lost their battle with the Chesterfield County, Virginia Planning Commission to allow Tucker, their pet pig, to stay in their home, but refuse to let the board keep Tucker away. (Oct. 22) Video provided by AP
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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