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

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

First, the big draw of the trip is the opportunity to see skuas. Skuas are large seabirds that get called fun things like the “pirates of sea” because of their big size and sometimes aggressive behaviors. They are a true pelagic species, meaning they only come on land to nest. Since no skuas nest in Maine, they can only be seen by going offshore when they are using the Gulf of Maine to feed during migration or their non-breeding season. This year we hit the jackpot with south polar skuas, a species that nests on the coast of Antarctica during the austral summer (our winter) then spends its winter (our summer) in the north Atlantic. In past years we felt lucky to see one or two, but amazingly this year we saw at least 11. It is possible that the passage of Hurricane Earl helped push some of the birds into the Gulf, but they’ve 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 Maine’s coast, the great skua, was unfortunately absent. We’ve been lucky to see one or two great skuas in the past. With so many south polar skuas around, it made us question why the great skuas were absent. I don’t want to jump to conclusions with such a limited sample, but it is worth noting that great skuas, which nest in the northeast Atlantic on islands like Iceland and Svalbard, were unfortunately hit very hard by avian influenza this summer. Sites in the UK that count migrating great skuas only saw 25% of the number of birds in August that should have passed by based on numbers seen in past years. Again, our one-day sample shouldn’t be used to make conclusions, but with the large die-off of these “pirates,” it does make me 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 great and sooty shearwaters. There were no listed records of Cory’s in Maine when Ralph Palmer wrote his 1949 “Maine Birds” though they have become fairly common in recent years, especially in late summer when the Gulf of Maine’s waters are at their warmest. As you probably know, the Gulf of Maine is now warming faster than 96 percent of the world’s oceans, and increases in species like Cory’s shearwaters are an obvious sign of marine life changing in response to the temperatures.

At least 18 Cory’s shearwaters were spotted last weekend during Maine Audubon’s “pelagic trip” out of Bar Harbor. The species had been seen only three other times during the annual excursion, now in its 23rd year. Doug Hitchcox photo

Our trip departs from Bar Harbor and usually heads east to Grand Manan Banks, putting us in some of the coldest waters in the Gulf. In the 23 years we’ve run this trip, we had only encountered Cory’s shearwaters three other times, each with just one individual encountered. This year, however, at least 18 individuals were counted in the waters off Hancock and Washington counties. Similar to the south polar skuas, perhaps their numbers were up in response to the offshore hurricane, but since these shearwaters tend to favor warm waters, it isn’t surprising to have seen them with sea surface temperatures in the low 60s, compared to past trips, like in 2015 when temperatures were 10 degrees cooler.

This year’s trip was incredible, with great weather and visibility, and experts such as Jan Pierson and Robby Lambert helping out. Other highlights included: nearly 30 lesser 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 merlin; two dozen puffins; and about 40 other species!

There is much we don’t know about the birds and other wildlife in the Gulf of Maine, but one thing is for certain: it is clearly changing. Join us on future trips or consider contributing sightings to projects like eBird or iNaturalist if you head offshore.

Do you have a nature question for Doug? Email questions to ask@maineaudubon.org and visit maineaudubon.org to learn more about birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug and other naturalists lead free bird walks on Thursday mornings, 7 to 9 a.m., at the Gilsland Farm Audubon Sanctuary in Falmouth.