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How Do Robins Find Worms

Dear Bird Folks,

I donít know if youíve answered this question before, but Iíd like to know how robins are able to find worms on our lawn. I was told that when they cock their head towards the ground, they are actually ďlisteningĒ for worms, but Iím not sure if thatís true.

Ė Paul, Sudbury, MA

Me neither, Paul,

I also donít know if Iíve answered this robin question before. You would think that in the eighty-seven years Iíve been writing this column this topic would have come up already, and perhaps it did; I honestly donít remember. Then again, the way things have been going for me lately, I could forget what Iím writing about halfway through this answer. Actually, it may seem as if Iíve forgotten the topic already because instead of discussing robins, Iím going to start off with a little environmental history lesson. But Iíll eventually get to robinsÖprobably.

According to my research, the expression ďThe early bird gets the wormĒ has been around for over four centuries. But guess what hasnít been around here for that longÖworms. Yes, you read that right. When the Pilgrims first landed, they discovered a lot of new and wondrous forms of wildlife, but they didnít find any earthworms. None. Our worms had all been wiped out by the last ice age and they never bothered coming back. This meant that in 1620 the American Robin, a bird long associated with eating earthworms, wasnít going to ďgetĒ a single worm, no matter how early it got up.

As is the case with starlings, gypsy moths and Norway rats (and many of us), the worms we find in our backyards today were brought here from Europe. More recently, a few other worm species have arrived here from Asia, including something called, and Iím not kidding, ďcrazy worms.Ē (Iím not sure what crazy worms are and I think Iíd rather not know.) The introduction of exotic species invariably creates problems, but these are just earthworms. They canít be a problem, right? It all depends upon whom you ask. Gardeners love worms for their ability to aerate the soil. Plus, Iíve never met a fisherman who dislikes them and many birds think worms are the very best things to ever come here from Europe (with the possible exception of the Beatles and, of course, pizza). So, is there a downside, you ask? Oh, thereís a downside. Thereís always a downside.

When I was growing up, back in my Norman Rockwell days, I had a Sunday morning paper route. At sunrise I would get up, pile those giant Sunday newspapers onto a rusted Radio Flyer wagon (the papers were too big and I was too small to carry them) and deliver them to the houses around the neighborhood. If it had rained during the night, the streets would be filled with worms, usually nightcrawlers. Fearing the worms might get squashed by passing cars, Iíd pick up every one and carry them to the safety of the nearest lawn. (I was even a softy back then.) By doing this, I not only saved the worms, but also contributed to the wellbeing of the lawn (while also insuring that every customer had a newspaper covered in worm slime that morning). If I had, however, released the worms into a wooded area or a forest, as fishermen and landscapers sometimes do, the outcome would have been different. Worms in a garden or lawn tend to be a good thing, but their eating habits reduce the organic matter on a forest floor. A healthy forest has a thick understory of vegetation that supports a variety of creatures, but it all disappears if worms are introduced. Now I feel bad about saving all those worms. Not only are worms bad for certain environments, but lawns arenít that great for the natural world either. Sorry, Paul, but itís true.

This brings us to the point where I actually address your question about robins listening for food. I know birds are better at hearing than we are, but do we really think they can hear worms? Are worms actually so noisy that robins can hear them above the sound of wind, traffic and lawnmowers? Maybe crazy worms can be heard, but thatís about it. Robins donít cock their heads towards the ground to listen, but to see. A foraging robin will move across the ground, pause for a moment and tip its head. With one of its eyes staring downward, the bird will search for any sign of movement or other indication that a worm is near the surface. If it sees what it is looking for, the bird will stab into the soil, and instantly there will be one less invasive worm to worry about. Done and done.

Hereís another question: If robins are such worm-a-holics, what were they eating before the early settlers arrived with their worms? Donít look at me; how old do you think I am? About 60% of a robinís diet consists of fruit and berries. Robins, especially during the breeding season, also consume a large amount of animal matter, including sowbugs, spiders, millipedes and assorted grubs. It should also be pointed out that we urbanites think of robins as ďlawn birds,Ē which is true, but robins also readily breed in remote locations of Canada and Alaska, where there arenít many lawns or earthworms, and those birds are doing just fine.

I, too, have read that robins hunt worms by hearing, Paul, but in his latest book, What Itís Like To a Be Bird, author David Sibley supports the visual theory and I agree. I have more to say on this topic, but Iím writing this on Saturday night, which means tomorrow is Sunday and I have to get up early. Those morning newspapers arenít going to deliver themselves.

Artwork by Catherine Clark

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