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The process of losing and replacing feathers is called the molt, and it is a uniquely bird event. Though snakes shed their skin, dogs their fur, and insects their exoskeletons, a bird’s molt is timed, ordered, and an astounding physiological process.
Our ambassador Broad-winged Hawk, Northfield, is an excellent molting educator, and this summer is helping visitors visualize the molt in action. As a second-year bird, Northfield came to VINS in June 2016, still with a coat of down. By late August he had grown in the full set of feathers that was his “juvenal plumage”, characterized by mottled brown on his back and wings, a brownish tail with multiple thin stripes, and most noticeable of all, heart-shaped brown splotches on his flanks and legs. This summer, Northfield is undergoing what ornithologists call the “prebasic molt” into his adult or “basic plumage”. His brown mottling is becoming darker and more reddish as new body feathers grow in. His tail feathers are being replaced by wide, starkly black-and-white stripes, and sadly, his “heart-pants” are giving way to russet horizontal bars on his chest.
Broad-winged Hawks are long-distance migratory birds, and so Northfield’s wild counterparts often have trouble fitting the entire molt in before September, when they must soar down the Appalachians to Central America. As such, some Broad-wings suspend the molt mid-summer, and finish it on their wintering grounds.
What should you do if you find a molted feather? Enjoy looking at it, then leave it be.
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