What is the adaptive function of the Tawny Frogmouth's paler underside plumage?

Answer

To minimize shadows when viewed from below against the sky

The paler underside acts as countershading, an adaptation that helps break up the bird's outline and minimize shadows when viewed from below against the lighter background of the sky.

What is the adaptive function of the Tawny Frogmouth's paler underside plumage?
birdanimalappearancecharacteristicFrogmouth