What bird is this? If you know the answer, you should be writing this column, because I got it wrong.
As experienced birders might recognize, it’s a jaeger. But which one? Jaegers are seabirds that nest in the arctic. The name comes from the German word for hunter. On their breeding territories, all jaegers take rodents, small birds and insects. Jaegers are opportunistic, and I once watched a pair raid the nest and eat the eggs of a Canada goose on Hudson Bay in Manitoba. On migration, jaegers primarily steal food from other birds, usually gulls and terns. They acrobatically chase and harass the other birds until they drop their meals. There are three species of jaeger that can venture into Maine waters, and two of them are devilishly difficult to tell apart.
It is with a certain amount of trepidation that I write today’s column, because mysterious birds that are only seen from boats are of little interest to many readers who are more entranced by the simple beauty of a backyard cardinal. But there is a point I would like to make. Sometimes bird identification just isn’t easy, not even for experts.
This bird is not a long-tailed jaeger. Long-tailed jaegers are very rare in Maine waters, though several have been spotted this year. All jaegers have central tail feathers that are abnormally long, but the lengthy streamers of a long-tailed jaeger are particularly striking. The bird is considerably smaller than its two cousins, so I think I can get that ID correct if I ever see one.
On the other hand, parasitic and pomarine jaegers are very similar. The pomarine jaeger is larger, but only by a couple of inches. Although they are about the same size as a gull, both species look much more muscular. Their long, pointed wings give them speed and agility. They bully their way around the ocean.
Today’s bird was seen right near the dock at Inn on the Wharf in Lubec. My birding group was just returning from a boat trip through Head Harbor Passage, hugging the shore of Campobello for most of the way. Suddenly, this bird lumbered by. Seth Benz snapped a photo, actually several photos. Our initial diagnosis: pomarine jaeger.
That night, Seth took a closer look at the photos on his laptop and began to question the accuracy of our identification. There are many challenges. For starters, both species come in several different color morphs. They don’t all look alike. There are light and dark variations and even an intermediate version. Additionally, young birds have their own plumage differences. To further complicate matters, female jaegers are 10 to 15 percent larger than males.
Louis Bevier is the expert that experts go to when they need help. The Central Maine resident is a member of the Maine Bird Records Committee, which is a group that deciphers the accuracy, likelihood and origin of unusual birds when they are reported in Maine. It’s important to determine if a bird wandered here on its own or if it may have escaped from captivity.
Wandering birds are scientifically significant. They can signal many things from natural range expansion to unnatural climate change. However, human-assisted birds don’t count.
Seth sent his photos to Louis, who confirmed the suspicion that the bird was actually a parasitic jaeger. Louis observed that the tail feathers were too long for a pomarine jaeger and the cap on the bird’s head did not extend below the chin — a subtle but invaluable clue. Furthermore, he posited that this was a young, heavy-chested female, which had given us the false impression it was the more powerful pomarine jaeger.
So if you’ve ever struggled with the identification of a tough bird, you’re in good company.
Clearly, I need to practice my jaeger identification skills. Fortunately, the best opportunity of the year is coming up next weekend. Every September, Maine Audubon takes over the Friendship V — the big, fast catamaran operated by Bar Harbor Whale Watch — for an eight-hour pelagic birding trip. Pelagic birds are birds of the open ocean, and there are thousands of them out there. Jaegers are routinely encountered, and the expert spotters on board will be looking hard for their larger cousins: great skuas and south polar skuas.
The boat leaves the Bar Harbor pier at 6 a.m. next Sunday, Sept. 17. Details can be found at https://maineaudubon.org/events/bar-harbor-pelagic-trip-2017. It’s one of Maine’s biggest birding events. Get some Dramamine and sign up.
Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.