This is a long report, very worth reading, of how the NPS investigated the deaths last year of two hikers, at least one of which was a very experienced backpacker from Michigan. While it appears (but remains uncertain) that the killings were from grizzlies, the authors note that it could very possibly be consistent with black bears, although none were found in the areas involved and one of the killings appears likely caused by a sow with cubs, serving as a good reminder that blacks can cause the same kind of killings. It's also significant that one of the killings occurred right on the trail, probably while the hiker was taking a morning snack break.

http://www.nps.gov/aboutus/foia/uplo...entsForWeb.pdf

The Weasel