Pectinate Claw

The short legs of a Common Nighthawk chick.  The pectinate claw has yet to develop on the middle and longest toe.

Some birds have a comb-like structure on one toe for grooming.  Dan Tallman wrote an excellent post on the difference between the Common Nighthawk and Heron’s pectinate claws.

Here’s a pectinate claw on an adult female in my study:

Nighthawk researchers have wondered whether this was a vestigial structure, an ancestral appendage that is no longer useful.  This is because nighthawks have short, stumpy legs.  They are clumsy walkers and are unable to perch in trees and instead lay on and parallel to limbs when roosting in trees.  So, are nighthawk pectinate claws useful when presumably they cannot reach their short legs to their plumage?

Presume no more!  They can and do reach their head with their feet while grooming.

Nighthawk itching head with foot

Having a hard time seeing the foot? Here it is.