 The black bears of Yosemite were once famous for breaking into parked cars to steal food . They were also an encouraged tourist sight for many years at the park 's garbage dumps , where bears congregated to eat park visitors ' garbage and tourists gathered to photograph the bears . Increasing encounters between bears and humans and increasing damage to property led to an aggressive campaign to discourage bears from relying on human food or interacting with people and their property . The open @-@ air dumps were closed ; all trash receptacles were replaced with bear @-@ proof receptacles ; all campgrounds were equipped with bear @-@ proof food lockers so that people would not leave food in their vehicles , which were easy targets for the powerful and resourceful bears . Because bears who show aggression towards people usually are eventually destroyed , park personnel have continued to come up with innovative ways to have bears associate humans and their property with unpleasant experiences , such as being hit with rubber bullets . Today , about 30 bears a year are captured and ear @-@ tagged and their DNA is sampled so that , when bear damage occurs , rangers can ascertain which bear is causing the problem . 
