It is also home to resident willow ptarmigans and Arctic terns. Birds include prairie falcons, white-tailed ptarmigans, and common ravens. The arms show three white Willow Ptarmigans "(Lagopus lagopus)" on a blue background. This suggests that the hens' food calls assist in enhancing survival rates of juvenile ptarmigans. The arms show three white-colored willow ptarmigans (Lagopus lagopus) on a green background. McCandless hunted porcupines, squirrels, and birds, such as ptarmigans and Canada geese. The tundra supports caribou and ptarmigans. It also eats ptarmigans, voles, and grouse. Although adult willow ptarmigans are herbivores, the newly hatched young also feed on insects. White-tailed ptarmigans have been monitored in Rocky Mountain National Park, Colorado, since 1966.