Naturally seeing deer in the eastern woods while running is always a thrill. Not that deer are rare, it's just that it's a real bonus of running.
That's why this article was a tad disturbing:
Deer aren't the slim, graceful vegans we thought they were. Scientists using field cameras have caught deer preying on nestling song birds. And it's not just deer. Herbivores the world over may be supplementing their diets.
You ought to go read the whole article. In Nature, remember: there is no right and wrong, there are only consequences.