Of ears and eyes, a lesson

The early bird gets the worm, but the second mouse gets the cheese. ~Author Unknown

Robins and Worms, Kimberly Weiss, Birding editor, BellaOnline

The first important study on how robins find worms was by Frank Heppner in 1965. According to his study, Heppner determined that robins use only their sense of sight to find worms. He put dead worms in a wormhole, worms that could not be making a sound or giving off a vibration. The robins were able to see the glistening flesh of the deceased annelids through the tiny holes and ate away!

The second famous scholarly article about robins and worms was published in 1997, by Robert Montgomerie and Patrick Weatherhead.

In this study, robins were able to locate buried meal worms using their sense of sound alone. In fact, Weatherhead and Montgomerie found that if they played some white noise the robins had trouble finding their worms. They concluded that robins use the sense of hearing to locate their prey. It doesn't say that they never use their sense of vision. Certainly, if a robin sees a silent worm on the on top of dirt, it will eat it. But somehow, robins were able to locate worms underground that they could not see, and Weatherhead and Montgomerie found that the sense of hearing was used to do that.

In two peer-reviewed journals, one scientist proved the hypothesis that robins use their eyes, another team proved their hypothesis that they use their ear holes (which are buried under their feathers.)Now, here is something interesting that was not brought up: meal worms and earthworms are completely different animals! Meal worms are not worms, but long, skinny insects. They are actually the larva of a beetle. They have a hard covering called an exoskeleton and six legs. An earthworm is soft, with no legs. They crawl on tiny, bristle-like setae

It is quite possible, that it is noisier when a hard, legged "worm" walks than when a soft, mushy worm does. In general, the harder something is, the noisier it is. Perhaps the robins could hear the meal worms but could not hear an earthworm. I don't know. For a hypothesis to become a theory, studies must be duplicated by other scientists, and this didn't seem to happen. It's obvious the second study is quite different from the first, as different prey is involved.

So how do robins find worms? It's safe to say they use both their senses of sight and hearing, to some extent. It is also clear, that this question is not exactly setting the ornithological world on fire. Thirty-two years went by between the first and second major robin/worm studies, and it's been years since the second. Maybe someone out there will get a Ph.D. in ornithology and finally answer this question once and for all.


"Avian hearing is much more sensitive than ours. Birds can hear a wider range of sounds, but have fairly specialized hearing ranges. Some hear higher pitches, while others hear lower ones, depending upon what nature gave them.

A bird has a small hole on each side of its head for ears that are covered with "auricular feathers." These feathers protect the ear opening, reflect sounds, and funnel sounds toward the opening. We all know what high winds do to a microphone outdoors, but this excess noise isn't a problem for birds, since the special feathers cut down on wind noise. " Lynn Bowen
The Avian Ear

American Robin