This is Bird Note. At a mountain summit in Vermont, among gnarled and stunted spruce and fur, dawn breaks with this unique sound.

The swirling serenade of a Bicknell's thrush.

Corduroy brown above and pale below, with messy spots on its breast, the thrush isn't really known for its good looks. It's known for scarcity and promiscuity.

Unlike most songbirds, the female thrush establishes a territory and then mates with males that happen by.

She then lays eggs that have been fertilized by multiple different males.

Many of those males will stick around and help feed the young, even if they are not their own. Bicknell's thrushes are exceedingly rare, and they face an uncertain future with climate change and habitat loss.

Yet each year, this little songbird makes the long journey from the Caribbean Islands to the forests of the northeastern coasts of North

America to make a call that a few of us may be lucky enough to hear in person.

For Bird Note, I'm Michael Stein.

Support for Bird Note is provided by Sarah Merner and Craig McKibbon from Seattle, Washington,

and generous listeners around the world.