Same with bears. For instance, the grizzly (brown) bears in Denali National Park who are farther away from salmon breeding areas (coastal areas) tend to eat a lot more berries than their coastal counterparts.

A wild animal documentary that I saw mentioned that stags would eat their own bloodied velvet hangings that were scratched off on branches ("velvet" is the living covering of the antlers at the beginning of the growing season).

It claimed "biologists don't know why the deer, which are herbivores, eat the bloody remains." Which is stupid, of course.

The answer is because deer can't read, so they don't know they are "herbivores".