Climate change fattens up grizzlies

One possible effect of climate change: chubbier grizzly bears. According to a new study, grizzlies in Canada tend to thrive when born during warmer years.

The researchers looked for evidence of the “silver spoon effect,” which refers to the long-term benefits that animals enjoy when environmental conditions are cushy immediately before and soon after their births. For example, a previous study showed that red squirrels born when the weather is warm and white spruce cones are abundant have better luck reproducing later on.

The team caught 112 grizzly bears over about a decade in the Rocky Mountains of Alberta, Canada and measured their mass, length, and body condition. The researchers also studied temperature and precipitation records in the area to estimate how much the weather deviated each year from the norm. Then they tried to figure out whether the bears’ body size was linked to factors such as the climate conditions one year before the animal’s birth, while in the womb, and shortly after birth.

The grizzlies tended to be heavier when the summer of their birth year was unusually warm and the winter was unusually wet, the team reports in BMC Ecology. Warmer springs during the birth year and warmer summers the year before birth were also linked to longer bodies. In general, bears in colder areas 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,” said study co-author Scott Nielsen of the University of Alberta in a press release. “A simple rule is, the fatter the bear, the better.” Roberta Kwok | 31 October 2013

Source: Nielsen, S.E. et al. 2013. Environmental, biological and anthropogenic effects on grizzly bear body size: temporal and spatial considerations. BMC Ecology doi: 10.1186/1472-6785-13-31.

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