It’s dress-up day for humans, when costumes are worn in exchange for treats. Your birds may be wearing new costumes of their own, having swapped out their brighter breeding plumage for the duller and more camouflaging feathers they sport in winter.
Being bright and noticeable is an advantage in spring and summer, when individual male birds compete for the attention of females who may use their coloration to judge their health. But when dating season is over, these bright colors are costly to maintain and can attract predators. Their new camo can make it harder for humans to visually identify birds like the American Goldfinch, Scarlet Tanager, and Indigo Bunting since they are less yellow, red and blue.
Other birds stay camouflaged all year, including many females which don’t need colorful feathers to attract a mate and instead improve their survival odds by blending into their surroundings. Hunting birds use their camo so they can sneak up on prey. New research on Barn Owls showed that when flying on clear moonlit nights, these owls’ white underparts make them nearly invisible to ground-dwelling rodents. It’s a trick called countershading that helps them nab a delicious treat.