What do you mean when you say the deers eat birds? Which kind of bird and have you seen this happen? Do you have a picture or video of a deer eating a bird. If that is true then we are physically changing. I enjoy watching deer in SC. I havent seen their diet change yet. If a deers diet changes then I expect everything else will also change.

Sounds like the deer is reprogramming itself for suvival. If plants are killed by cold weather than the next best thing to do is eat some meat. Peace be to you.