Ask Maine Audubon: Gulf of Maine Bird Species Are Clearly Changing

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South Polar skuas nest on the coast of Antarctica and then travel to the North Atlantic in summer. During the Maine Audubon’s “pelagic voyage” out of Bar Harbor last weekend, at least 11 southern polar skuas were spotted – far more than ever before on the annual excursion. Photo by Doug Hitchcox

On September 10, Maine Audubon hosted its annual “pelagic trip” from Bar Harbor, a boat trip in search of various birds (and we’ll slow down for fish and mammals) that can only be seen with a dedicated effort. Over the course of the day we had some interesting observations that I wanted to share as they help shed some light on some of the changes we are noticing in Maine birds that are rarely seen and seldom discussed.

First, the big draw of the trip is the chance to see skuas. Skuas are large seabirds that are called funny things like “sea pirates” due to their large size and sometimes aggressive behaviors. It is a true pelagic species, that is to say that it only comes on land to nest. Since no skuas nest in Maine, they can only be seen going offshore when using the Gulf of Maine for food during migration or their non-breeding season. This year we hit the jackpot with the Antarctic skuas, a species that nests on the coasts of Antarctica during the austral summer (our winter) and then spends its winter (our summer) in the North Atlantic. Over the past few years we’ve felt lucky to see one or two, but surprisingly this year we’ve seen at least 11. It’s possible the passage of Hurricane Earl helped push some of the birds in the Gulf, but they have been reported regularly off Grand Manan, albeit one or two at a time, since late August.

The other species of skua that can be seen off the coast of Maine, the great skua, was sadly absent. We’ve been lucky enough to see a great skua or two in the past. With so many Antarctic skuas around, it got us wondering why the great skuas were missing. I don’t want to jump to conclusions with such a limited sample, but it should be noted that the great skuas, which nest in the northeast Atlantic on islands like Iceland and Svalbard, have unfortunately been very hard hit by bird flu this summer. Sites in the UK that have migrating great skuas saw only 25% of the number of birds in August that should have passed based on numbers seen in recent years. Again, our one-day sample shouldn’t be used to draw conclusions, but with the high mortality of these “pirates,” I wonder if that was the cause of their absence this year.

Another interesting change was the presence of Cory’s Shearwaters. Cory’s shearwaters are a large shearwater that generally prefer warm waters, especially compared to our more common tall and sooty shearwaters. There were no recorded records of Cory’s in Maine when Ralph Palmer wrote his 1949 “Maine Birds”, although they have become quite common in recent years, particularly in late summer when the waters of the Gulf of Maine are the warmest. As you probably know, the Gulf of Maine is now warming faster than 96% of the world’s oceans, and the increase in the number of species such as Cory’s Shearwaters is a clear sign of the evolution of marine life in temperature response.

At least 18 Cory’s Shearwaters were spotted last weekend on Maine Audubon’s “pelagic trip” from Bar Harbor. The species had only been seen three other times during the annual excursion, which is now in its 23rd year. Photo by Doug Hitchcox

Our trip departs from Bar Harbor and heads generally east to the Grand Manan Banks, placing us in some of the coldest waters in the Gulf. In the 23 years we have organized this trip, we have only encountered Cory’s Shearwaters three other times, each with a single individual encountered. This year, however, at least 18 individuals have been counted in the waters off Hancock and Washington counties. Similar to the southern polar skuas, their numbers may have increased in response to the offshore hurricane, but since these shearwaters tend to prefer warm waters, it’s no surprise to have seen them with surface temperatures of the sea in the 60s, compared to the past. trips, like in 2015 when temperatures were 10 degrees cooler.

This year’s trip was amazing, with great weather and visibility, and experts such as Jan Pierson and Robby Lambert helping out. Other highlights include: nearly 30 great black-backed gulls, a rare but increasingly common species since they began nesting in Greenland in the 1990s; several migrating songbirds, including a mourning warbler and several purple finches that landed on the boat, seeking shelter from a pursuing swivel; two dozen puffins; and about 40 other species!

There’s a lot we don’t know about the birds and other wildlife of the Gulf of Maine, but one thing is certain: it’s clearly changing. Join us on future trips or consider contributing to projects like eBird or iNaturalist if you’re heading overseas.

Do you have a nature question for Doug? Email questions to [email protected] and visit maineaudubon.org to learn more about birding, native plants, and Maine wildlife and habitat programs and events. Doug and other naturalists run free Thursday morning bird walks from 7-9 a.m. at Gilsland Farm Audubon Sanctuary in Falmouth.


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