This is Birdnark.

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

surprises unique to the season.

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

in cognito.

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 mold.

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 mold?

Because feathers wear out.

Songbirds, like the scarlet tannager 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.

Bird Note's newsletter delivers the wonder and joy of birds directly to your inbox.

...