October 29, 2013
Grizzly Bears May Benefit From The Effects Of A Warming Climate
[ Watch the Video: Warming Climate May Benefit Grizzly Bears ]
April Flowers for redOrbit.com - Your Universe Online
In contrast to many species, including our own, global warming and forest disturbances may have a silver lining for threatened species of grizzly bears in Alberta, Canada.
University of Alberta biologist Scott Nielsen and his team monitored 112 bears in Alberta's Rocky Mountain region over the course of 10 years. He and his colleagues found that warmer temperatures and easier access to food associated with forest disturbances helped the grizzlies to build more body fat, known to increase the chances of successful reproduction for mothers.
Nielsen, an assistant professor in the U of A Department of Renewable Resources, said that the resulting 'silver spoon effect' shows that grizzly bears born into these favorable conditions have a head-start in life. The findings of this study were published in BMC Ecology.
"Understanding variations in body size helps us understand what limits grizzly populations," Nielsen said. "We get clues about the environments that most suit grizzlies by examining basic health measures such as body size. A simple rule is, the fatter the bear, the better. Certain environments promote fatter bears."
The team hopes their findings might someday help influence forest harvest designs to enhance habitat for the Alberta grizzly, which is classed by the Alberta government as a threatened species. At this time, there are only approximately 750 grizzlies in Alberta, with only half of those being adults.
The body size of adult bears was found to be larger in years when warmer temperatures and less late winter snow brought on earlier spring conditions. In colder and less productive environments, or years that were abnormally cool, the adult bears were smaller.
"We hypothesize that warmer temperatures in this ecosystem, especially during late winter and spring, may not be such a bad thing for grizzlies," Nielsen said, noting that historically the range for the bears once extended as far south as Mexico and persists today even in the deserts of Mongolia. "That suggests the species won't likely be limited by rising temperatures which would lengthen the growing season and the time needed to fatten prior to hibernation."
Nielsen said that bears using disturbed forest habitats containing a wide variety of stand ages were healthier, as well.
"The diversity of stand ages in the landscape has a positive influence on body condition because bears are better able to access a wide range of food sources."