National Geographic: The recent controversy over a bison calf in Yellowstone is just the latest in a series of tough choices on wild animals in trouble.
This bison calf was euthanized earlier this month after it was placed in a car by a visitor to Yellowstone.
Maybe it's a baby robin that falls out of a nest in the backyard, or perhaps twin deer fawns left orphaned after their mother gets struck by a car or eaten by wolves, or perchance a bald eagle, behaving strangely, staggering on the ground and unable to fly....