Study: Urban areas are the ultimate 'bear trap'

Yogi might have claimed to be smarter than your average bear, but a new study finds that his lifestyle of hanging around humans wasn't the smart choice.

It turns out that urban black bears are much heavier and more likely to die violent deaths than their wilder peers, the study found. Oh, and if female, they're more likely to get pregnant at a younger age.

"Urban areas are becoming the ultimate bear traps," Wildlife Conservation Society researcher Jon Beckmann, the study’s lead author, said in a statement Tuesday. "Because of an abundant food source — namely garbage — bears are being drawn in from backcountry areas into urbanized landscapes where they meet their demise."

In the study, 12 female bears living in urban areas around Lake Tahoe, Nev., were tracked over 10 years and compared to 10 female bears that lived in outlying wild areas.

"Bears in urbanized areas weighed an average of 30 percent more than bears in wild areas due to a diet heavily supplemented by garbage," WCS stated. "The authors believe that because the bears weigh more they are giving birth at an earlier age — on average when they are between 4-5 years old, as compared to 7-8 years for bears in wild areas. Some urban bears even reproduced as early as 2-3 years of age around Lake Tahoe."

Bears dies younger
The study also found that urban bears tend to die much younger — mostly due to collisions with vehicles. All 12 urban bears that were tracked were dead by age 10 due to vehicle collisions, while six of the wilder bears still survived.

The researchers also tracked bear deaths around the region in recent decades. "We found that almost 9 bears have been killed annually by vehicles from 1997–2008," they said in the study. "This represents a 17-fold increase in bear mortalities due to bear–vehicle collisions since the late 1980s."

So while human garbage is providing food for bears, they appear to be dying sooner and thus their populations are unable to grow in more urban areas.

"Urbanized areas are functioning as 'sinks' for black bear populations, drawing in bears from outlying wild areas, where they ultimately die," WCS stated. "As a result, bears are failing to recolonize outlying wild areas following this shift to urban centers."

Nevada's black bear population is thought to be steady for now due to bears moving in from California, but the researchers feel that could be temporary and that by removing the "sinks" the local population might actually increase.

The study was published in the Fall 2008 issue of the journal Human-Wildlife Conflicts.

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