Chestnut-Backed Chickadee in Snow, Snohomish County, Washington
A chestnut-backed chickadee (Poecile rufescens) rests on the branch of a snow-covered rhododendron in Snohomish County, Washington. Chickadees use nocturnal hypothermia, allowing their core body temperature to fall at night to conserve as much as one-third of their energy.