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Ospreys Vie For Nesting Platforms

Dear Bird Folks,

The other day I witnessed at least six different Ospreys swooping around a nesting platform in Sandwich (MA). Two birds would sit on the platform but then another pair would drive them off. The new birds would then be driven off by yet another pair. Are these birds related? Was this a family group of two adults and four kids that have returned from last summer? Do Ospreys usually return to the same nest each year?

– Priscilla, Dennis, MA


Yes, no and maybe, Priscilla,

I wrote “yes” because, yes, Ospreys typically do return to the same nest site each year. Who needs the hassle of finding a new vacation home every summer? They all have the same musty smell no matter where you stay. I wrote “no” because, no, none of the birds you saw hatched out of that nest last summer. Ospreys don’t breed until they are three or four years old. Young Ospreys usually spend the first year or two of their lives on their wintering grounds, which is most likely Brazil. That is where they learn to catch fish and how to dance the bossa nova. And lastly, I said “maybe” because…hmmm. I had reason for that but it’s gone now. Don’t you hate that? Oh well, it will come to me later. Maybe.

I like Ospreys. To me they are the poor man’s Bald Eagle. Ospreys don’t need to be in remote locations in order to breed. Any utility pole, water tower or manmade platform works for them. They don’t even mind if we creepy humans live near their nest. A guy who lives down the street from me has an active Osprey platform right in his front yard. His front yard! (I can’t even get bluebirds in my yard and this guy gets an Osprey.) Bald Eagles would never nest that close to us. If you want to see lots of eagles you usually have to travel to some out-of-the-way wilderness, like the kind found in Maine, Wyoming or Alaska. I’ve never been to Alaska, but everyone tells me that Bald Eagles are everywhere. I guess I should go someday. It would be nice to see all those eagles, plus get a good look at Russia at the same time.

Even though Ospreys aren’t as fussy as eagles, they still need to be selective about their nest site. If they choose the wrong location their eggs may become food for an assortment of predators, including our old pal, Mr. Raccoon. You might think that a bird as powerful as an Osprey would have little trouble defending its nest. But raccoons work at night, which puts the birds at a disadvantage. That is why Ospreys try to choose nest sites that are either over water, on isolated islands or at the tops of very tall structures. Once the birds find a suitable location, and are successful raising a family there, they don’t want to ever give it up. They will return to the same nest year after year and are more than willing to fight any other Ospreys that may try to take it away.

Right now you might be thinking: “If every bird returns to the same nest each spring, why is there fighting? Wouldn’t every pair already have a nest from the previous year?” Unfortunately, homelessness is as much a problem for birds as it is for humans. Winter storms are constantly knocking down old trees, which may have supported nests that were used for years. And uptight power company officials often remove nests from utility poles for reasons only known to them. Then there are the new couples. Ospreys that have finally reached the breeding age are in the market for a good starter home. It may be a buyer’s market for us (that is, any of us who still have a job), but such is not the case for Osprey newly weds. Good spots are tough to find. Ospreys are always experimenting with odd sites in the hope that they can somehow turn them into a proper nest. Just today a lady called me about a pair of Ospreys that were trying to build a nest on the cupola of an area middle school. You know the birds are desperate if they want to live near middle school kids.

Hey, I remember why I wrote “maybe.” You asked if any of the fighting birds were “related.” The answer is maybe. When Ospreys are finally old enough to breed they will return to the same area where they were born. Without leg bands it would be hard to know if the battling birds are parents and offspring. But none of it makes any difference to the parents; they hate the intruding birds either way.

Four of the birds you saw, Priscilla, were most likely young or homeless Ospreys that were trying to take over that nest site from an established pair. In all likelihood the nest’s rightful owners will eventually drive off the potential usurpers and begin the business of raising a family. The other birds will move on and continue their search for a place to breed. If they find a good spot then they’ll probably have kids of their own. If they don’t find a place to nest, then they’ll probably spend the summer hanging out at the beach and doing the bossa nova. I vote for option two.