John Chan / Female Downy woodpecker nestling (Picoides pubescens) peering out and calling from the entrance of its nest cavity, begging to be fed, Southern California, USA, May.

Sebastian Kennerknecht / American Bison (Bison bison) herd grazing in winter, Gardiner, Yellowstone National Park, Montana

Sebastian Kennerknecht / American Bison (Bison bison) herd grazing in winter, Gardiner, Yellowstone National Park, Montana

Sebastian Kennerknecht / American Bison (Bison bison) female cleaning nose with tongue, Yellowstone National Park, Wyoming

Sebastian Kennerknecht / American Bison (Bison bison) female in winter, Yellowstone National Park, Wyoming