Black bears are one of the most adaptable of all large carnivores and readily raid human sources of food, such as trash cans, bird feeders, and campgrounds. But are bears foraging selectively for these resources or just taking advantage of a random opportunity? To get at an answer, NWRC's Dr. Stewart Breck and collaborators at Yosemite National Park studied black bears to determine whether they foraged selectively for human food sources, particularly those found in cars. From 2001-2007, bears broke into 908 vehicles at Yosemite National Park. Every year, minivans had the most or second most number of vehicles broken into. Use of minivans (29%) was more than four times higher than expected (7%) based on availability of different vehicle models. Researchers hypothesize that black bears select minivans over other car models in an effort to maximize caloric gain and minimize costs by targeting vehicles with higher probabilities of payoff. So why are minivans more desirable?
Dr. Breck notes, "It is possible that minivans were more likely to emit food odors regardless of whether they contained food or not. This is because minivans are designed for families with children and small children are notorious for spilling food and drinks while riding in cars."
Breck also notes other potential reasons why bears selected minivans:
--minivan owners may be more prone to leave large caches of food in their vehicles because they have the space,
--minivans may be easier to break into than other vehicles, or
--the data could just reflect the foraging decisions of a few individual animals that have developed a learned behavior for breaking into minvans.
Dr. Breck plans to continue working with park officials to develop management strategies that include greater education efforts focused on vehicles carrying small children, increased enforcement efforts focused on vehicles violating food storage regulations, and management of select problem bears.
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