I tried to put the wolves in pastures but that didn't work. I tried butchering animals to provide meat for them and still it didn't work.
I'd have to agree with @Pierre-Luc.
After doing some easy googling for you, I looked at the raw-files for Wolf, Eagle and Bear, and they all lack the [STANDARD_GRAZER] token. The wiki page about Black bears even states specifically:
Bears in general lack the [GRAZER] tag which means they don't require pastures. This makes them an ideal component of a meat industry.
Did these animals die from wounds, or perhaps some other reason?
Animals stored in cages, as long as they are "non-grazing" (for example wolves), can stay alive without being fed. See:
for details on caged creatures.