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Dunlins Arrive When Other Shorebirds Leave

Dear Bird Folks,

Like many retired people living on Cape Cod I like to walk the beaches, especially now that the crowds have disappeared. On yesterday’s walk I came upon a large flock of sandpipers probing in the mud at low tide. Unfortunately, the only description I can offer you is that they were about the size of robins and they were very plain looking. Any guesses?

– Ned, Osterville, MA


They were Dunlins, Ned,

The sandpipers you saw are called “Dunlins.” I’m 100% positive that’s what they were. I promise you. Actually, the truth is I don’t know for sure what kind of birds you saw. But since you don’t know either, I may as well just pick a name out of the bird book. What can you do about it? You can’t prove me wrong. It’s not like you have photos or… Wait. You don’t have photos, do you? Because if you do, you have to tell me so I can backtrack on my promise. I’m allowed to do that in mid-November. The rule is that anytime after an election we can backtrack on whatever promises we’ve made. If you don’t believe me, look it up. It’s in the rulebook. I promise.

The truth is the birds you saw most likely were Dunlins, but I’m not happy about it. Dunlins are kind of dull to write about, and even worse to read about. (They probably should be called “Dull-ins.”) Dunlins are sandpipers, one of the roughly twenty-five different species of sandpipers that visit the Cape each year. Starting in July and running through October, Cape Cod is home to huge flocks of assorted migrating sandpipers. By November, most of the sandpipers have flown further south, but oddly, this is when the Dunlins arrive. They are hardy birds, even if they are dull.

With a population approaching four million birds, Dunlins are one of the most common and widespread sandpipers in the world. They are found in Asia, Africa and Europe, as well as North America. Dunlins can be seen on Cape Cod every day of the year but are down right abundant around here in the late fall. In the spring they have a distinctive plumage that features a rusty back and cap, with a black patch running across the belly. By the time fall rolls around, their belly has become totally white, while the rest of the bird has molted into a boring gray-brown. In fact, the bird’s common name, Dunlin, means “little dun-colored bird.” (Remember that; it could be in a crossword puzzle someday.)

Dunlins should not be confused with their smaller cousins, the Sanderlings. Sanderlings, which are also found here in the fall, are highly energetic sandpipers. Their feeding behavior is one of continuous motion, constantly racing about looking for bits of food. They appear to be perpetually late, always running to catch the bus. The Dunlins’ feeding style is more relaxed. They wait for the bus to come them. You said the birds you saw were “probing in the mud.” That’s a good clue. A Dunlin feeds methodically, carefully probing in sand or mud with its long beak. If it finds something yummy during one of these probes it will jam its entire beak into the mud, all the way up to its face, looking like a dog trying to root some creature out of a hole. From a distance the Dunlin’s constant up and down probing motion resembles a “sewing machine.” At least that’s what the books say. I wouldn’t know. I’m more of a knitter.

The other clue you gave me was that the birds were in a “large flock.” That is another Dunlin trait. Every day is Thanksgiving to them, as they like to eat in the company of all their friends and relatives. If you see a large flock of sandpipers on Cape Cod, and the calendar says it’s November, you can bet that the flock will be mostly Dunlins. I’m not saying that there won’t be another species or two mixed in, but the majority of the birds will be Dunlins. Foraging in a large flock has its advantages, but it also has one major disadvantage. A large flock of birds on an exposed mudflat is an open invitation to avian predators, and there’s one avian predator that will readily accept the invitation.

Sandpipers are extremely fast and agile flyers. Most owls, hawks or even eagles don’t have the flying skills to successfully hunt them. However, there is one bird of prey that can easily meet this challenge. I’m talking about falcons. Falcons are faster than fast and Dunlins are a sitting duck (really) when a falcon is around. In an effort to avoid a falcon attack, the entire flock will rise up as a solid mass of birds and then will zigzag through the air as one tight coordinated unit. As the flock turns, the Dunlins alternate flashing their gray backs and their bright-white undersides, giving them a strobe light effect. I’m not sure how much this maneuver fools the falcons, but it sure looks cool.

Dull or not, Ned, I’m glad you noticed the Dunlins. You’ve reminded us that there is more to bird watching than just sitting on the couch and staring at birdfeeders all day. Hold on. I can’t believe I just said that. (I think I’d better backtrack once again.) What I meant to say is that buying birdfeeders and birdseed is absolutely the best way to see birds. Whew! That was close.