Photographer: Alan Lipkin, MD, Denver, Colorado. “White-tailed ptarmigans are the smallest members of the grouse family. They are year-round residents of the Colorado mountains above the treeline, and they feed on willow buds. They are not particularly strong fliers, so they evade predators by being among the best camouflaged animals in the alpine environment. In the summer months they have a gray and tan feather coat that changes to nearly pure white in the winter. Hikers commonly walk right by them without detecting their presence. After years of trying, I was finally able to find one and photograph it.”