The Union Democrat newspaper reports that visitors to Yosemite National Park are threatening the bear population.
Last year, 25 black bears were struck by vehicles in the park and most likely died. Officials say they don't have accurate numbers on bear deaths since most return to the woods after being struck and die soon after.
In addition, park officials say some bears have had to be euthanized after becoming too hostile or too reliant on stealing food from campsites and cars.
The newspaper reports that there were 535 incidents involving bears in Yosemite during 2009. That's up from 422 in 2008, which may, in part, be due to higher attendance, according to park spokesman Scott Gediman.
Yosemite has launched public information campaigns, posted signs within the park, and provided bear-proof food storage lockers in camping areas to help teach visitors about the problem and to help them avoid bear incidents.
Officials have also started enforcing the food rules with 210 night patrols in 2009. The inspections resulted in 7,862 food storage violations, more than 1,900 written food storage warnings, more than 1,000 verbal warnings and 54 food impoundments.
"Bears are really afraid of people unless they become habituated to them," Gediman said. "Our goal is to not have them associate cars and campsites with food."
He notes that about five bears are put down each year because of being too aggressive.