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Oystercatcher Feeding Techniques

Dear Bird Folks,

While walking around Deer Island in Boston Harbor I happened to see two American Oystercatchers. Since oysters aren’t all that elusive, it’s probably pretty easy for them to be caught by the birds. Do oystercatchers eat anything that’s a challenge to catch, or do they just chill out and eat oysters all day?

– Jake, Winthrop, MA


Cute, Jake,

That trip to Deer Island must have had quite the effect on you. I see you’ve even substituted “deer” in place of “dear,” as in “Deer Bird Folks.” But I understand your confusion. For some reason, whoever invented the English language thought it would be cute to use the same sounding-word for two completely different things. What were they thinking? If they are going to go through all the trouble of making up a language, the least they could do is use different sounding-words to mean dissimilar things. Words like no/know, see/sea and wear/where drive me nuts. I once signed up for a math class because I thought I was going to learn about pie. Apparently, there is a mathematical word that sounds just like pie, but doesn’t mean the same thing…and isn’t nearly as yummy.

Bird names can also be confusing. There’s a lot more in a sapsucker’s diet than just sap. Flycatchers eat all kinds of insects, not just flies. And cowbirds will only eat the occasional cow. The American Oystercatcher has similar issues. In fact, in our area, oystercatchers eat very few oysters. The bulk of their diet consists of marine worms, clams and mussels. (Or are they muscles? See, there’s another one of those annoying words.) And speaking of things with misleading names, not only does the aforementioned Deer Island not have any deer, it’s not an island. Go figure.

For those of you who don’t know, oystercatchers are shorebirds, large distinctive looking shorebirds. With their bright-white bellies, jet-black heads and crazy bright yellow eyes, oystercatchers are hard to miss. But none of those gaudy features compares to the bird’s most important field mark, the beak. The beak of an oystercatcher is thick, very long and glowing red/orange. From a distance the bird looks like it’s eating a carrot or a cardinal that has told a lot of lies. (Think about it.)

This massive beak may look like it’s for show, but it’s actually the bird’s most important tool. As you probably have already figured out, they use these large beaks to catch food. However, in your note you asked if the birds “eat anything that’s a challenge to catch.” I don’t want to read anything into your question, Jake, but you appear to be implying that oystercatchers have it easy because they feed on prey that doesn’t move. Sure, catching oysters might not be the most difficult thing to do, but opening them is where the challenge comes in. There are websites and online videos that teach people the art of opening oysters. According to these websites, to open an oyster you’ll need a pair of gloves, a sturdy knife and two strong hands. With a little practice opening an oyster should become easy. Now, try opening an oyster without any of those tools. Just use your face. That’s what oystercatchers use. Oystercatchers have no knives and no gloves (because they don’t have hands to put them on), yet they can remove an oyster from its shell faster than humans can open a bottle of cocktail sauce. (I hope that last reference made sense. I don’t eat oysters or use cocktail sauce, but I think I saw somebody use it in a movie once.)

When hunting shellfish, oystercatchers use two main methods. The first is to slowly walk through submerged shellfish beds and to keep a sharp eye out for any lackadaisical mussels or oysters that haven’t closed their shells yet. Upon seeing an open oyster the bird uses lightening quick beak-stabs to sever the adductor muscle that enables the bivalve to close its shell. Once that’s cut the battle is over. When arriving at an area where all the shellfish have their shells closed tight, the bird goes to plan B. It will pluck the shellfish out of the water and carry it to a drier location. Then it becomes hammer time. The bird will use its formidable beak to break through the part of the shell that protects the adductor muscle. After that, there is nothing for the bird to do but open a jar of cocktail sauce and enjoy.

Once extirpated from Massachusetts by market hunters, the American Oystercatcher is slowly making a comeback. In 1969 the first nest in forever was discovered in Chappaquiddick. (I think I spelled that right.) A year later a pair fledged three babies on Monomoy, and by the 1989 a few birds had pushed as far north as the islands in Boston Harbor. The return of the American Oystercatcher has been rewarding to see, especially for those folks who have worked so hard to protect beaches and critical nesting areas from loose dogs, SUVs, and loose dogs driving SUVs.

I’m glad you were able to see oystercatchers on your walk along Deer Island, Jake. There were way too many years when that wasn’t possible. However, even though you are now able to see an oystercatcher and you can write oystercatcher, I doubt you can pronounce oystercatcher. People from Winthrop, Boston and the part of Massachusetts where I grew up, have zero chance of ever saying that bird’s name correctly. Heck, I’m still working on saying Nomar and he’s been gone for nearly ten years.