were intended both to provide a spectacle for park visitors and to lure bears from the rubbish dumps of hotels that were created alongside Yosemite in 1890.
After the last feeding site was closed in 1971 both rare carbon and nitrogen isotopes remained elevated in bear tissues when compared to specimens from those that did not eat human food. Recently these isotopes have decreased significantly. Since Yosemite started receiving federal funds human foods have dropped in bear diets by 63%. It is extremely likely that bears in the park eat today as their ancestors did in the early 1900s.
The change comes thanks to rangers successfully encouraging 99% of visitors who stay overnight to use bear-proof food lockers in campgrounds and car parks, and to take bear-proof canisters in the backcountry (loaned to backpackers for free). Both thwart ursine attempts to reach provisions. It is far more cost-effective for park authorities to prevent black bears from eating what they should not than it is to protect people from rogue creatures seeking human food, and to tidy up after them.
Dietary patterns revealed in this study show the dangers of synanthropization: the adaption of animals to people and the environments they foster. The proportion of human food in black bear diets increased, understandably, due to the intentional feeding of bears during the 20th century. It remained high even after feeding sites and the fishery were closed—the animals had grown accustomed to forbidden foods and so continued to forage for them near humans. Bears also would have passed their predilection for human grub on to their offspring, making the situation worse (earlier work by Dr Hopkins details the problematic dietary effects of social learning on cubs).
Black bears that persistently sniff out campers’ hampers have to be killed by park staff eventually (as occurred on a large scale in the 1960s). Nature lovers should keep their food very close when visiting Yosemite therefore.