A couple of mule deer are on the lookout for wolves and other predators in a meadow in Yellowstone National Park. Although it was once thought that wolves would only cull the old and sick members of a herd, research has found that wolves take the youngest deer first, those less than a year of age.

(Text adapted from and photograph shot on assignment for, but not published in, "Return of the Gray Wolf," May 1998, National Geographic magazine)