Scientists Can Now Track the Roseate Tern’s Migration—and Identify Dangers Along the Way

The solar is simply beginning to set off the tip of Galinhos, a peninsula in northeast Brazil, and Rafael Revorêdo is holding a beer koozie as he sits in a folding chair with legs which have sunk deep into the sand. Not like most individuals visiting this tropical paradise on a heat February night, he’s not right here to chill out. As a biologist at Centro de Estudos e Monitoramento Ambiental (CEMAM), a neighborhood conservation NGO, he’s right here to check Roseate Terns, migratory seabirds named for the fragile pink hue their breast and stomach feathers tackle throughout breeding season. 

The koozie is an improvisation on a Pringles can—an improvisation itself—that Revorêdo and his colleagues will use to carry every tern they catch whereas they weigh it. (The native market was out of the chips.) He’s lining the container with parchment paper to verify the birds’ lengthy, skinny payments don’t get caught in its Styrofoam inside. Whereas each unbanded Roseate Tern they catch will obtain a novel ID bracelet, the researchers are particularly interested by capturing as much as 15 people heavy sufficient to additionally sport GPS tags. As soon as affixed to the terns, these trackers will collect information the researchers hope will assist defend Roseates and different seabirds whereas permitting renewable vitality growth to advance.

The elegant and imperiled seabirds have lengthy discovered a haven in Galinhos, however offshore wind growth poses a rising threat. With its sturdy, constant gales, the Galinhos coast is taken into account “the filet mignon of wind” in Brazil, says Revorêdo. Onshore wind farms are already properly established within the area and contribute considerably to Brazil’s renewable vitality targets. Now there’s rising curiosity in offshore wind farms. There are at the least 12 proposed projects that if constructed might create a wall of generators that presents a probably lethal impediment for Roseates.

Each night from November by means of early April, Roseate Terns return from lengthy days of foraging at sea to roost on the seashores in Galinhos. A lot of the birds are members of the northeast inhabitants, which was hit arduous a century in the past, first by the millinery commerce after which by growth and rampant predation by gulls and different animals on their breeding grounds. As we speak these websites are closely managed, however the inhabitants nonetheless isn’t recovering. “It appears clear that there are different threats holding them again,” says Don Lyons, director of conservation science at Audubon’s Seabird Institute. “We’d like info on the place Roseates are once they’re not at their breeding colonies.” 

By monitoring the birds, Lyons, Revorêdo, and their colleagues are hoping to get a extra detailed image of the paths the birds take—and the place intervention is likely to be warranted. 

A Path to Security

On this tagging journey in February 2025, the researchers will work till the wee hours, 4 nights in a row, making an attempt to catch Roseate Terns as they return to land. Because the sky darkens, the researchers start enjoying Roseate calls from audio system arrange behind mist nets that catch the birds as they return to land. The primary night they catch 4 Roseate Terns in fast succession, two of which have already got bands. Keenan Yakola, an Oregon State College Ph.D. scholar, seems to be up the primary, which he discovers is from Maine, the place he additionally calls house. He instantly is aware of the second fowl is from Nice Gull Island, a significant breeding colony web site off Lengthy Island, due to the quantity sequence on its band. 

The staff begins with the tern from Maine. Working within the tender crimson glow emanating from their headlamps, Yakola calls out its measurements, and Lyons jots them down. At 113 grams, the fowl is hefty sufficient to sport a GPS tag. The tern lets out a couple of squawks as Yakola passes it to Revorêdo. “It’s okay, sweetheart,” Revorêdo whispers to the fowl. “Mild, light.”

Yakola slips the tag’s straps, manufactured from Stretch Magic, often used for making necklaces, across the tern’s legs. He then adjusts the tag so its weight is properly distributed throughout the fowl’s decrease again, its antenna pointed tailward. The devices report location, altitude, velocity, and different information each quarter-hour; the staff collects the trove of knowledge by way of radio receivers because the birds fly by them at their breeding and nonbreeding grounds. That is the primary of 15 birds that may obtain a GPS tag this season—the identical quantity they tagged the earlier yr. (They’d tag extra if they might, however at $700 per unit, 15 is what’s within the funds.) 

When he finishes, Yakola rigorously takes the fowl from Revorêdo and turns it upright. “I’ll see you in Maine,” he says, as he releases it into the air with a toss, his palms going through the sky because the fowl opens its wings and takes flight.

The tags deployed over the previous two years have revealed that the birds in Galinhos are likely to make straight flights between their seaside roosts and shelf breaks about 30 miles offshore, the place fish are recognized to congregate within the upwelling of chilly, nutrient-rich water—info that might affect the siting of recent generators to keep away from tern highways. Over that very same interval, radio receivers the researchers deployed at breeding colonies within the northeastern United States captured, for the primary time ever, the precise migration routes of seven Roseates. In November the staff celebrated one other first: monitoring the southern journeys of three terns, together with one tagged in Galinhos final February. The info point out that terns might overlap with offshore wind growth and energy strains at varied factors all through their migration.

As offshore wind expands right here and throughout the birds’ vary, the scientists hope their findings will assist officers mitigate potential hurt. Interventions may embody portray turbine blades to extend visibility, adjusting turbine peak, and siting wind initiatives to keep away from tern highways.

A Steadiness of Energy

Despite the fact that the terns’ nesting colonies alongside the U.S. East Coast are protected, the birds expertise challenges all year long. Local weather-driven adjustments take a toll in the course of the breeding season: Extra highly effective storms flood and erode nesting websites, and marine warmth waves alter the distribution of fish that terns subsist on, inflicting younger birds to starve. 

What’s extra, the renewable vitality wanted to assist stem world warming can pose dangers to the birds. Collisions with wind-energy transmission strains have been as soon as the main energy-related risk to the small seabird in Galinhos. In 2014, quickly after the primary wind farms have been constructed there, volunteer wildlife screens with CEMAM started noticing a distressing pattern: Lifeless and injured Roseate Terns have been turning up close to the world’s newly put in energy strains.

In 2017 alone, they discovered 110 Roseate bodies. A number of of the lifeless or injured birds had been banded as chicks on Nice Gull, Ram, and Hen islands, the main tern breeding grounds off the East Coast of the USA. The screens at CEMAM reached out to Helen Hays, an American ornithologist recognized for her seminal work restoring Widespread and Roseate Tern populations, notably on Nice Gull Island. Hays, in flip, relayed the information to ornithologist Joan Walsh, who had additionally labored on Nice Gull.

“I can do every part proper on Nice Gull Island and make you an additional 500 child Roseate Terns, however what good is that if, once they fly to Brazil, they encounter a thousand offshore wind generators?” says Walsh. “We have to perceive what that risk panorama is throughout their complete vary to do good conservation.”

Walsh labored with the scientists at CEMAM, together with Revorêdo, to raised perceive what can be required to cut back or keep away from mortality. Certainly one of their experiments included utilizing markers from a Colorado-based firm referred to as Energy Line Sentry, which they spaced alongside distribution strains. The markers had two sorts of stripes that enabled terns to see the wires: one which displays daylight in the course of the day and one other that absorbs it after which glows at night time. The markers have been put in in December 2021, and subsequent monitoring discovered that the intervention dramatically diminished the variety of deaths.

“We work tirelessly all yr to attempt to hold that species shifting ahead on its restoration monitor,” says Walsh. “Once you uncover the biggest anthropogenic kill that’s reversible, you do one thing.”

That’s why the researchers at Galinhos spend all night time tagging birds. By mapping Roseate Tern actions, they hope their findings will assist officers mitigate potential hurt as offshore wind expands off the Brazilian coast and all through the birds’ vary. As troublesome and time-consuming as it’s to observe avian mortality on land, it’s even tougher at sea, the place carcasses rapidly disappear. Interventions to forestall damage and loss of life may embody portray turbine blades to extend visibility, adjusting turbine peak, and creating structure-free corridors in key areas to supply secure passage. “We’d like renewable vitality,” says Yakola. “However it may be finished in a means that advantages each individuals and wildlife.”

This story initially ran within the Winter 2025 situation as “Protected Passage.” To obtain our print journal, grow to be a member by making a donation today.