By Kimberly Ridley
Photographed by Tristan Spinski
From our June 2023 Island Issue
Great Duck Island is a notoriously tough place to land a boat. There’s no dock, just a steep, slippery ramp on the island’s exposed south side, which can only be approached in a Zodiac on a day when seas are under four feet. But one afternoon late last September, a pair of students from Bar Harbor’s College of the Atlantic finessed the landing and hauled hundreds of pounds of boat and passengers partway up the ramp — saving us not only from slipping but also from the dreaded “ass slapper,” a ledge where breaking waves tend to soak one’s derriere.
Time was short on this trip to Great Duck, 10 miles south of Mount Desert. The goal was to button up the college’s field station for the winter and have one last quick look for some of the world’s most mysterious seabirds — not ducks, despite the island’s name, but Leach’s storm-petrels, diminutive and dusky cousins of the albatross.
Few people have ever seen these starling-size seabirds, which have gunmetal plumage, white rumps, and hooked black bills topped with odd tubular nostrils. They live far out to sea and come ashore only to breed on remote northern islands, where they nest in shallow underground burrows that can wind and twist for up to six feet, excavated by the males in spruce forests and meadows. Parents travel to and from their burrows only at night, filling the air with eerie chuckles that sound like goblins doing helium.
Making storm-petrels stranger still: their distinctive aroma, which has been described as pleasantly musty. It’s a result of the oily plankton soup that adults make in their stomachs to feed chicks, combined with the musk of their nurseries’ earthen interiors. “Like rich, sun-warmed soil,” says COA senior Eleanor Gnam, who has studied petrels on Great Duck for the last two summers. “Or like very old library stacks.”
Great Duck Island hosts the eastern U.S.’s largest known breeding colony of Leach’s storm-petrels, but you’d never know it to explore the narrow, mile-long island. As Gnam and I walked a rutted track last September, there wasn’t a bird in sight besides a few gulls loafing on the ledges. But she assured me we might well be surrounded by storm-petrel chicks. During the fledgling season, hundreds if not thousands of them hunker in hidden burrows that riddle the spruce forest and meadows. I very much wanted Gnam to find one, in part for a peculiar and selfish reason: I’m an avid birder with a quirky bucket list. Not only did I want to see a petrel, I wanted to smell one too.
Gnam paused at a fist-size hole beside a thick, mossy spruce root. She lay belly-down and reached in to “grub” for a chick. Her arm disappeared up to her shoulder. No luck. She tried again at several more burrows, but the chicks had already fledged. Just as I was beginning to doubt whether we’d find one, Gnam patiently reached into yet another hole, beside a patch of ferns. Shifting to lie on her side, she reached deeper still, her cheek pressed to the forest floor. And then: “Oh!”
“It’s okay, buddy,” she murmured, and, ever so gently, she extracted a fuzzy gray powder puff the size of a baseball. The chick nestled in her cupped hands, its eyes hidden under a mop of down. She examined the young bird’s long wings. “Look at you,” she said. “You’re almost ready to fly.”
Eleanor Gnam’s most recent survey involved counting burrows in 607 sample plots, each 100 meters square. “It’s a good thing we had June, July, and August, rather than the usual two-month field season,” she says.
Gnam has grown fond of these enigmatic birds, whose underground domestic lives and nocturnal lifestyle make them notoriously difficult to study — censusing Leach’s storm-petrels has been called “counting the invisible.” For her COA senior thesis, she’s trying to discern how different methods of counting storm-petrels on Great Duck have led to wildly different population estimates, ranging from 800 to 27,000 pairs, over the past 50 years. Her findings will contribute to recommendations for consistent methods to estimate populations, which will help researchers gauge the health of colonies.
Getting an accurate tally is becoming increasingly urgent. Petrels — along with other birds of their order, Procellariiformes, known as tubenoses —are among the world’s most imperiled birds. Researchers at some of the world’s largest breeding colonies, in Newfoundland and Labrador, report worrying declines in the number of Leach’s storm-petrels. Surveys by researchers at these colonies, some of which number in the millions, have reported population drops ranging from 42 to 61 percent. The International Union for Conservation of Nature lists the species as vulnerable, Canada’s wildlife agency classifies the petrels as threatened, and Maine’s Department of Inland Fisheries and Wildlife lists them as a “species of special concern.”
It’s hard to pinpoint what’s causing the declines, but the birds face numerous threats, including loss of breeding habitat to development and changes in forest cover, rising ocean temperatures that affect distribution of prey like zooplankton and small fish, and predators such as gulls, crows, otters, and mink. Light pollution from offshore drilling can disorient storm-petrels, inhibiting migration, and like many other seabirds, they sometimes mistake flecks of floating plastic for plankton and feed it to their chicks.
Top left: Landing on Great Duck. Bottom right: College of the Atlantic undergrad researcher Eleanor Gnam.
Gnam handed the chick to me. The small bird felt impossibly light, a quivering warmth in my hands. I admired the tiny, black, tube-nosed bill, the dark, intelligent eyes. Then, I brought my nose low and breathed in the chick’s odor: old books, mingled earth and ocean.
Petrels nesting on Great Duck have contended with human neighbors since at least the 1830s. As on many other Maine islands, farmers brought sheep, whose grazing denuded habitat. Settlers’ dogs and cats took a toll on both birds and their eggs. Snowshoe hares, introduced by lighthouse keepers in the mid-20th century for food, eat tree seedlings, inhibiting the forest cover that birds prefer for nesting.
Today, Great Duck’s major landowners are the Nature Conservancy and the state, which bought up most of the island in the 1980s to establish a seabird refuge. But it’s as much a classroom as a sanctuary: the former Great Duck Island Light Station is now COA’s Alice Eno Field Research Station, and students are permitted from April through October, when the island is otherwise closed to the public. Working with ecology professor and field station director John Anderson, they study nesting seabirds that include black guillemots, eiders, herring and black-backed gulls, and Leach’s storm-petrels. Gnam, a Wisconsin native, was hooked on Great Duck from her first visit. “I think islands and seabirds — extreme places and animals of extremes — inspire humility and curiosity,” she told me.
Gnam reaches into a burrow in search of a Leach’s storm-petrel chick.
Last summer, Gnam and a research assistant clambered over blowdowns and combed swaths of the forest floor to complete the most comprehensive survey to date of the island’s Leach’s storm-petrel colony. Covering a larger portion of the island than previous surveys, they sampled plots to find petrels’ well-hidden burrows. To estimate how many were in use, they applied an occupancy formula determined during a previous study, in 2021, when Gnam and others monitored burrows with game cams and set up “stick tests” — lattices of twigs and popsicle sticks placed over burrow entrances, which birds must remove to enter.
Researchers with more limited time have used the quicker method of counting along transects, tallying burrows while walking predetermined parallel lines. Whatever the survey method, researchers then extrapolate from their sample counts to estimate the number of occupied burrows on the entire island. Based on her data, Gnam puts the island’s Leach’s storm-petrel population somewhere between 6,500 and 10,000 pairs — far fewer than two recent counts by COA students and another by National Audubon Society researchers, all of which used transect surveys. This doesn’t necessarily mean the island’s petrel colony is shrinking, Gnam points out —determining that will require applying the same survey methods across enough years to see trends.
The sun was sinking behind the spruce woods as we returned to the boat for the 90-minute ride back to Mount Desert. I handed the petrel chick back to Gnam, who set it on the ground. She gave it a gentle nudge, and we watched it totter back into the darkness of its burrow.
Left: Alice Eno Field Research Station director and professor John Anderson has been studying petrels and other seabirds on Great Duck for some 30 years. Right: Grubbing for petrel chicks.
Some night not long after, the young petrel’s parents stopped feeding it and set out for their equatorial wintering grounds, off the coast of South America or Africa. The chick crawled out of its burrow to leave this small island, flying out over the trackless ocean, a place it had never seen. It used its extraordinary sense of smell to find patches of plankton far offshore. Hovering over the waves, it pattered the surface with its black webbed feet to stir up plankton, appearing to walk on water — the reason for which it was named after the Biblical Apostle Peter. With luck, in five years or so, that bird will find a mate and a safe island for nesting. The pair will take turns incubating their single egg for 40 days and feeding their chick for another 70. With more luck, they will live 30 years or so, returning to the same island every year to continue the story of their kind.
Back on the boat, I watched Great Duck grow smaller. From a distance, such little islands might appear unremarkable, but one never knows the secrets and strange wonders they harbor. As I raised my binoculars to watch the island fading into the distance, on my hands I caught the faintest whiff of musty old hardcovers.
