Fuel economy, it seems, is just as important to black bears in Yosemite National Park as it is with many visitors. And so when the bruins shop for fuel, more and more they tend to find themselves munching out in minivans, according to a study published in the Journal of Mammalogy.

Yep, while BMWs are sleek, Subarus utilitarian, and Tacoma's rugged, the best meals seem to show up time and again in minivans, according to the study.

For a seven-year period, the top choice of vehicle by black bears in Yosemite National Park has been the minivan. The bears seem to base this decision on “fuel efficiency”—that is, which vehicle offers the best opportunity of finding a meal. As a result, black bears have shown a strong preference for breaking into minivans over other types of vehicles.

The study, written by Stewart W. Breck, Nathan Lance, and Victoria Seher of the U.S. Agriculture Department's Wildlife Service and published in this month's issue of the journal, counted the number of vehicles broken into by make and model. From 2001 to 2007 minivans had the largest or second-largest number of incidents; when the number of break-ins was compared to the numbers of each type of vehicle visiting the park in 2004 – 2005, only minivans were broken into at a rate higher than expected based on their availability, noted the authors.

As Yogi would have you know, Yosemite's black bears are not your average bears!

Potential costs to bears came in the form of energy spent breaking into vehicles and considerable risk because park rangers were deployed nightly for surveillance and bears detected in or around campgrounds and parking lots received aggressive negative conditioning. The trade-off between food acquisition and penal actions by humans likely pressured bears to target vehicles with the highest probability of attaining food.

There are several non–mutually exclusive hypotheses for why bears selected minivans. First, it is possible that minivans were more likely to emit food odors regardless of whether they contained meaningful amounts of food available. This argument is based on the fact that minivans are designed for families with children and small children in particular are notorious for spilling food and drink while riding in vehicles. Thus, vehicles transporting children would emit greater food odors, making them attractive to bears.

If this hypothesis is correct then any vehicle transporting small children, regardless of class type, should be targeted by bears. To test this supposition, park personnel collecting information on vehicles broken into should also note whether car seats were present, or whether small children are regularly transported in the vehicle, or both. Second, it is possible that passengers of minivans were more prone to leave large caches of food (e.g., coolers or grocery bags) in vehicles parked overnight.

Evidence from the incident reports supports this contention by indicating that most vehicles broken into (regardless of vehicle class) had evidence of available food. What is unknown from these reports is the amount and type of food available, which could vary from micro-trash resulting from children to large quantities of food such as coolers or grocery bags.

Passengers of all vehicles entering Yosemite National Park are exposed to the same educational material regarding storing food in food lockers rather than vehicles and it is difficult to imagine why drivers of minivans would be biased toward leaving food in their vehicles. Additional data to evaluate this hypothesis could include the quantity and types of food present in incidents. Third, it is possible that minivans were structurally easier to break into than other vehicles.

Our observations indicate that bears entering minivans typically did so by popping open a rear side window and it seems that this was easier for minivans compared to other vehicle classes. We note that bears are strong and well equipped (long claws) to open a variety of structurally sound materials (e.g., logs and ant mounds), and we commonly saw car doors bent open, windows on all sides of the vehicle broken, and seats ripped out, all of which appeared effortless for bears.

Finally, selection of minivans could reflect the foraging decisions of a few individuals that developed a learned behavior for breaking into minivans. Anecdotal evidence supports this idea and indicates that most of the break-ins resulted from a maximum of 5 bears and possibly as few as 2 individuals.

Reports detailing 908 vehicles broken into by Yosemite black bears between 2001 and 2007 were reviewed. The rates of break-ins for nine categories included: minivan, 26 percent; sport-utility vehicle, 22.5 percent; small car, 17.1 percent; and sedan, 13.7 percent.

In conclusion, the authors suggested not only that park rangers redouble their efforts to warn visitors about leaving food in their vehicles, but could also possibly "include greater education efforts focused on vehicles carrying small children..."