I’ve had my share of challenging appearance changes (all self-inflicted, of course). Parachute pants in the 80s. A George Clooney haircut in the 90s. But that’s a far cry from the annual – and sometimes biannual – transformation birds endure. It’s called molting, and the process is nothing short of astounding.

The majority of passerines (songbirds) will molt in late summer. During that time, they’ll replace every feather on their bodies. How many? Well, for reference, a Black-capped Chickadee has a peak count of 2,500 feathers, so the answer is “a lot.” Sometimes old feathers simply fall free. If not, songbirds will pluck them out. Either way, they’ve gotta go. While molting, songbirds are ravenous – and for good reason. Feathers are made of keratin (the same as our hair and fingernails), and account for 25% of songbirds’ protein weight. Growing all that back takes a lot of energy. And a lot of food.

So why do it?

Feathers are everything to a songbird. Besides enabling flight, they also provide critical warmth, waterproofing, camouflage, and communication for courtship and territorial displays. However, by late summer those feathers are in sorry shape, pummeled by the demands of breeding season, plus nibbled upon by mites, bacteria, and other parasites. A Pennsylvania songbird with tattered plumage would never make it through winter, and a seasonal migrant, such as the House Wren, would fall far short of making it to its Amazonian wintering grounds.

However, if songbirds molted all feathers simultaneously, they’d be grounded and therefore an easy meal. Nature, in its infinite wisdom, has a plan to mitigate this. Songbirds molt flight feathers on their wings and tails first, one at a time, moving sequentially from those closest to the body to the periphery. This keeps them in the air. Only when flight feathers are replaced will songbirds begin work on their numerous warmth-giving body feathers. And when that’s all done…they can look forward to repeating the entire process once again next season.

So, if you see an especially natty Northern Cardinal or Flicker this fall, please pay it a compliment. It went through a makeover the likes of which you and I can’t comprehend.