This is a bird nub.

A roughly circular hole, chiseled by a woodpecker into the face of a tree trunk is not an unusual sight in nature.

What is unusual is seeing what lies beyond the opening.

The whole leads to the interior of the tree, a passageway to the nesting chamber carved below.

Inside this private space, layered with wood chips, a pair of woodpeckers will lay eggs and

raise a brood.

The chamber must be carved deep enough to accommodate the growing family.

Just as Woodpecker's species vary greatly in size, so do cavities. The chamber of a tiny downy woodpecker

descends about a foot from the opening.

The crow-sized piliated woodpecker may chip out a chamber two feet deep.

These birds usually breed only once a year. may chip out a chamber two feet deep.

These birds usually breed only once a year

and typically lay three to five eggs.

Most North American woodpeckers create a new cavity each spring.

An aging trunk may reveal a long history of nestholes.

Deep lineages of woodpecker families.

For Bird Note, I'm Mary McCann.

Bird Note, I'm Mary McCann.

Birdnote celebrates the everyday actions of our listeners

and the work of our conservation partners to reverse the alarming decline in North American birds.

Together, we can bring birds back. Learn more and get involved at birdnote.org. you're