This is Bird Note.

A day of watching birds is nearly always a day of surprises, and in August day brings surprises

unique to the season.

You can see some songbirds in patchy, almost unrecognizable plumage, as if they were going incognito.

You can see songbirds with gaps in their wings, entire feathers gone missing, and most jarring, the occasional bird with absolutely no tail.

What's going on? Well, many birds, which by August have just finished the intense rigors

of nesting and raising young, now undergo a complete molt. Mold is a cyclic process of feather

growth. As new feathers begin to grow in, they push the old ones out.

In the next few weeks, some birds will replace all of their feathers.

Why do birds molt?

Because feathers wear out.

Songbirds, like the scarlet tanager and hooded warbler we've been hearing, birds that migrate

long distances need to complete this process on a tight schedule. They need to be ready before

it's time to strike out for Central America in September. So, sometimes all the tail feathers fall

out at once, leaving a bird for a few weeks looking rather ungainly.

For Bird Note, I'm Mary McCann.