The Stormy Petrel II, a 60-foot fishing and seabird touring boat, steamed away from North Carolina’s Outer Banks on a recent winter morning. Its captain, Brian Patteson, is widely considered the godfather of pelagic birds along the Atlantic Seaboard. He was taking me out to find a transient spot along the continental shelf where Northern Gannets gather. By mid-morning I could see a stark delineation in the water off our bow. On one side, emerald, nutrient-rich water cooled by the Labrador Current flowing south from the Arctic; on the other, the midnight blue of the Gulf Stream, the warm, swift current that originates off the tip of Florida.
This boundary is ever shifting off the Outer Banks—sometimes as close as a few miles from the coast, other times as far as 20. Wherever it is, life teems. As we coasted to a corkscrewing bob above the swells, loggerhead turtles floated by, their heart-shaped shells rolling in the current. Below them circled 20 or so hammerhead sharks.
What brought us here was the spectacle off our starboard side. Hundreds of Northern Gannets jostled for space among 3,000 seabirds. Pelicans and gulls scrummed near two shrimp boats, which puttered along churning up fish. The gannets, meanwhile, hovered 30 or 40 feet overhead, occasionally making their trademark daring dive: hurtling toward the water, then tucking their wings in just above the surface as if they were feathers on the shaft of an arrow.
The gannets’ vocalization reached a fever pitch, alerting their kin in the area. Soon a cloud of more than a thousand of the six-foot-wide seabirds amassed around us, shrieking as they whizzed through the air and rained down upon the ocean at dizzying speeds.
Then, as quickly as they arrived, the enormous birds disappeared. “That’s the thing about gannets,” said Patteson, shaking his head. “They don’t think anything about picking up and moving from one state to another in a single day.”
Northern Gannets are built for speed, frequently flying and diving faster than 60 miles an hour. The species spans the North Atlantic; here in North America, gannets breed in six colonies in southern Canada and overwinter at sea from New England to the Gulf of Mexico. They can cover vast distances quickly, and often must, to keep up with the schools of menhaden and other forage fish they pursue.
In the coming years, gannets zipping along the Eastern Seaboard will encounter unprecedented obstacles. In the United States 17 offshore wind sites are under development in the Atlantic, from Cape Cod at the north end down to North Carolina’s Outer Banks, just miles from where Patteson and I observed the gannets’ feeding frenzy. Once completed these wind farms will create a network of turbines along the East Coast continental shelf like nothing else on Earth.
While nobody knows what toll the looming structures might take on seabirds, scientists say gannets may be especially vulnerable. North American populations have stopped expanding over the past decade. Scientists pin the leveling off on warming oceans near their breeding grounds that have altered their prey base. Here, on their wintering grounds, climate change is evident, too. A decade ago Patteson and I would never have seen shrimp boats in January: Back then the North Carolina shrimp harvest was negligible in cold winter waters. Now nearly 40 percent of the annual harvest is caught between December and March. “You can’t help but notice things are changing,” Patteson told me as the Stormy Petrel II headed back to port.
Shifts in the food web, sea-level rise, marine heat waves, and more changes are expected to intensify and accelerate over the coming decades as global temperatures warm. But much damage can still be slowed or even reversed if carbon emissions decline. Doing so will require society-wide changes, including converting U.S. electricity sources from carbon-emitting fossil fuels to clean energy generated by wind and the sun. And so the Northern Gannet, and other bird species, are in an unfortunate bind: They are seriously threatened by climate change, but offshore wind—one of the most aggressively sought correctives—may prove deadly to them, too.
Scientists understand the potential impacts of offshore wind on Northern Gannets better than they do for many other marine animals thanks to research on the species’ interactions with existing wind farms in Europe. They know the technology comes at a cost. But it’s a trade-off many are willing to make.
“Global warming is coming at us so fast we don’t have a choice but to adopt offshore wind,” says wildlife biologist Shilo Felton, field manager for Audubon’s Clean Energy Initiative. “This isn’t even as simple as ‘damned if you do, damned if you don’t.’ Gannets are certainly damned if we don’t.”
The Northern Gannet’s life history is as riveting as an operatic melodrama. The seabirds raise their young in packed colonies on cliffs in the North Atlantic’s upper latitudes—cramped places marked by fierce competition. Gannets will injure or kill each other over nest sites, slicing neighbors or even errant chicks with a rapier-sharp beak. To fledge, chicks hurl themselves off the cliff’s edge, sometimes falling 50 feet before gaining the momentum they need to glide down to the ocean. In the weeks before their flight feathers fully grow in, they bob along ocean currents learning to fish. In optimal years, fat stores buoy the young birds. But lean foraging seasons can cause crisis for young gannets still unable to fly. Those that survive range far and wide along the continental shelf for three or four years in search of prey. By the time they return to the breeding colonies as mature adults, they’re massive and powerful, capable of diving more than 70 feet deep.
That very physiology is, at least in part, what makes them so vulnerable to collisions with turbines. For all their speed and power, gannets suffer from tunnel vision. The binocular view that allows them to spy prey fathoms deep keeps their focus trained on the ocean below rather than on obstacles in front of them. It’s not uncommon to see gannets collide with each other while in a feeding frenzy. That, plus their preference for flying at the same height as a turbine’s rotor sweep zone, has led scientists to suspect that they have an especially high risk among seabirds for fatal collisions.
At the same time, studies have shown that, while some gannets will forage amid turbines, most tend to avoid them altogether—a kind of habitat loss that scientists call “displacement.”
“It seems counterintuitive that gannets could be at both collision and displacement risks,” Felton says, “but research suggests it’s true.”
What remains unknown is how the extra energy spent to avoid the turbines, combined with the potential drop in food availability if they lose all hunting grounds associated with the wind farms, will affect birds like gannets. Scientists assume they will be harmed, but they can’t say how significant those impacts will be.
Those potential future threats pile on top of existing ones. As apex predators, gannets are poisoned by toxins in the food chain, and they are prone to deadly entanglements with ocean debris and fishing nets. William Montevecchi, a biologist at Memorial University in Newfoundland, has studied seabirds, including gannets, for 40 years. He suspects that changes to the food web, induced by warming waters, are the cause of gannets’ reduced breeding success in North America. Mackerel, the species’ preferred food when breeding, is in increasingly short supply. When waters warm, mackerel may swim deeper in the water column, presumably out of range of even the gannet’s impressive dive depths, and leave the area for colder waters.
When food is scarce, it can spell disaster for young birds. A particularly bad season came in 2012, Montevecchi says. Many nests remained empty from the start. Of the eggs laid, only about 40 percent fledged. Chicks were often seen begging for food from parents who returned empty-beaked. Then, one morning in early August, observers near the colony on Cape St. Mary’s in Newfoundland awoke to discover that virtually all adults had abandoned the colony overnight. More than half of the chicks died. Montevecchi and his colleagues suspect that a marine heat wave (a stretch of five or more days of exceptionally warm ocean temperatures), coupled with severe thunderstorms, caused the desertion. Since then, abandonment has become more common on Cape St. Mary’s. In 2014, 2015, and 2018, 20 to 30 percent of breeding adults fled.
Despite this recently rocky record, gannets in North America keep returning to the same colonies. No matter how densely packed or food-scarce the sites become, the birds haven’t made any known attempts to establish new colonies, even when there appears to be suitable habitat nearby.
“It’s such a paradox,” Montevecchi says. “These are probably the most aggressive birds, period. They fight the bloodiest battles and are capable of horrific bloodletting, but they won’t expand beyond these six colonies.”
If the gannets won’t move, even as their breeding habitat and food sources degrade around them, then their best hope lies in our ability to curb emissions and our wider environmental impact.
Ten miles off the North Carolina coast, the upper deck of the Stormy Petrel II offers a good vantage into the uncertain future of pelagic seabirds like the Northern Gannet. From this perch the Outer Banks seems almost a mirage: miles of shimmering sand punctuated only by the insinuation of lighthouses. Seventeen miles to the northeast amid the flat expanse of sea is the 122,405-acre lease site destined to become one of this country’s first offshore wind farms.
The plan for Kitty Hawk Wind is ambitious: up to 69 wind turbines with towers rising as high as 500 feet, each equipped with blades spinning in a circumference that may reach heights of 1,000 feet above sea level at their apex. Two export cables, buried about six feet below the seabed, will ferry the generated electricity—2,500 megawatts annually, enough to power 700,000 homes when it’s completed in 2026—to onshore substations. Sixteen similar projects are planned from here to Cape Cod, where construction has begun on Vineyard Wind. That project, located 14 miles off Martha’s Vineyard and planned to be up and running in 2023, will include 62 turbines each set a nautical mile apart. All of these projects, which will come online over the next decade, will dwarf the nation’s single existing offshore wind farm, which consists of five 300-foot-tall turbines that have been spinning off Rhode Island since 2016.
Seventeen wind projects under development along the U.S. Atlantic Coast are slated to go online in the next decade.