You may have heard me talk about those marauding avian pirates of our nearshore waters, the jaegers. Fast and unrelenting, they chase terns and gulls in an effort to steal their fish, comfortable atop the local seabird food chain. But for at least one day this past weekend, the jaegers fell a few rungs on the seabird corporate ladder. A true pirate of the Caribbean was in town - a Magnificent Frigatebird was photographed on Stellwagen Bank.
Since I was a little kid flipping the pages in my first bird book, I’ve always loved the frigatebird. Maybe you’ve seen the breeding displays of the males in some nature special somewhere – they inflate a bizarre, bright red throat sack, making it look like they are trying to choke down an enormous Red Delicious apple. In fact, that’s exactly what I thought they were doing in the illustration I saw when I was six years old. I wasn’t the brightest kid.
Sporting an eight-foot wingspan, the frigatebird is an imposing figure among seabirds. While they catch much of their own food, mainly squid and flying fish snatched from the air in tropical and subtropical waters, they also engage in piracy, which is known in the animal behavior field as “kleptoparasitism”. A word that only scientists could conjure, kleptoparasitism, simply put, is stealing food from other animals. While jaegers are the best known practitioners around here, frigatebirds are the quintessential warm water kleptoparasite. Despite their enormous size, they are supremely agile fliers. Through acrobatic pursuit, they harass smaller tropicbirds and even fairly large species like the Blue-footed Booby until they disgorge their food.
When not in hot pursuit, frigatebirds are seemingly effortless fliers. If you spend any time watching them, you’ll be struck by how seldom they actually flap. They are reported to be one of the only species that will ride out a hurricane on the wing. Oddly, their plumage is not even waterproof, and they are rarely seen on the water.
We’ve likely missed our chance to see this bird on Cape Cod, as a frigatebird seen up in Scarborough Maine on Monday is certainly this same one. This all begs the question: why was a Magnificent Frigatebird on Cape Cod, and even stranger, Maine? This is a bird you are most likely to see during your tropical island getaway in February, not so much on a chilly, early season New England whale watch. Perhaps this bird heard the news that the Gulf of Maine is warming faster than any other water body on the planet – in fact, it’s projected to continue warming at 3 times the global average. Southern species of fish are charging northwards into the once chilly Gulf, like the black sea bass currently eating their way through all the juvenile lobsters in Maine. Sightings of tropical Brown Boobies in New England have increased in recent years. And an individual of yet another tropical bird, the appropriately named Red-billed Tropicbird, has been summering on an island offshore of Maine for the last 10 years. Perhaps these birds are trying to tell us something. And that something may be “pull up a chair and fix yourself a rum punch – the tropics are coming to us.”