Here in bear country, most habituation of bears to human food seems to occur in camp grounds and in towns like Mammoth Lakes, where much more human food is available to bears than in backpacker's Ursacks or whatever other containers they might be using. In towns like Mammoth Lakes the odor of human food cooking in homes and restaurants must be a strong attractant.
Human food only accounts for a small percentage of the overall calories consumed by bears over a Summer season. (Please don't ask me for statistics, it's just makes sense.) Most of a bear's diet is vegetation, which is what they need in order to really pack on the fat. BTW, according to the Mammoth Lakes bear officer, there is an abundance of natural forage for bears this year; much more than in the Summer of 1212. During the second drought year...go figure. Read what Steve Searles has to say on the topic:
http://www.thebearwhisperer.com/Having said that, it is true that wilderness bears that roam through areas frequented by backpackers have learned to recognize food containers by sight. Hence, the experience of seeing bears rolling hard-sided containers around and trying to get into them. Backpacker's camps and their cooking odors are bound to attract bears.
If some backpackers are concerned about habituating bears to human food, they ought to just stay home...
