A bison peeks under the truck sheltering National Geographic photographer Joel Sartore, on assignment at the Maxwell State Game Preserve near Canton, Kansas.
One of fewer than 10 woodland caribou (Rangifer tarandus caribou) in US zoos, Costello the caribou would stand patiently anywhere in exchange for a reward of grape leaves. Meanwhile in the wild, woodland caribou are nearly absent from the lower 48 states because they rely on old-growth forest habitat. Just a few holdouts still cross from Canada into northern Idaho and Washington. The total U.S. population is 40 individuals. (US: Endangered)