Facial Disc and Hearing

From Alexandra Zwack

A LITTLE KNOWLEDGE ABOUT BIRDS OF PREY - The facial disc and the arrangement of the ears in owls

The facial disc of owls have a purpose: The special arrangement of the feathers around the eyes amplifies and directs sound waves directly to their ears. - like a kind of parabolic mirror, it collects the sound and directs it more precisely to the ears.

These are located exactly on the focal point of the facial disc, on both sides of the head. Many people think that these often seen "ear tufts" ARE the ears of the owls. But no! The ears are inside and hidden. Some of the owls don't even have these "decorative tufts"! Little owls, for example.

The owls that have them use them to express their mood. It is very important for the night hunters to be able to orient themselves even in complete darkness and to locate their prey using their sense of hearing.

In order to be able to locate the rustling of prey precisely, the ears are also slightly offset(*) (unlike humans, which are positioned at the same height).

The slight time shift of the sound in the ears provides the owl with a more precise location and allows it to determine the exact distance of the sound.

Examples of the facial disc in the pictures are of a Siberian eagle owl and a White-faced owl.

Even in a young bird that is about 5 weeks old, it can already be seen clearly.

(*) Note - not all owls have asymmetrical ears!