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. When researchers in North Dakota set up “nest cams” over the nests of song birds, they expected to see a lot of nestlings and eggs get taken by ground squirrels, foxes, and badgers. Squirrels hit thirteen nests, but other meat-eaters made a poor showing. Foxes and weasels only took one nest each. Know what fearsome animal out-did either of those two sleek, resourceful predators?...