Coastal Birds Are Ditching the Beach to Nest on Rooftops

Last June, coastal bird technician Chloe St. Germain-Vermillion found herself chasing a tiny, speckled Least Tern chick through a cavernous New Orleans storage center. As the leader of a new conservation program run by Audubon Delta, she’d been keeping a keen eye on a tern colony nesting on the building’s flat roof, from which the bird had tumbled. After a slapstick scramble to catch the uninjured hatchling, she returned it to its home surrounded not by sand and sea, but by parking lots and an elevated highway.

The sight of coastal birds hatching atop buildings may be incongruous, but it has become common as oceanfront development, beach recreation, and sea-level rise create a crunch in natural habitat. In Florida, Black Skimmers, American Oystercatchers, and around half of the state’s Least Terns are among the birds that opt for the high life. Gulls, terns, and shorebirds also now breed on buildings in cities such as Chicago; Seattle; Portland, Maine; and Charleston, South Carolina. In New York, intense development along the Hudson River spurred Herring Gulls to colonize a convention center’s vegetated roof in midtown Manhattan. “This is going to be something that we see play out around the world,” Myles Davis, senior manager of green infrastructure at NYC Bird Alliance, says of the trend.

Whether rooftops truly provide safe harbor for seabirds is less certain. Though sheltered from terrestrial threats such as coyotes and crabs, roof-bound chicks are vulnerable to falls, sun, and aerial predators such as crows and raptors. Extreme heat and worsening storms linked to climate change may increase the risks of rooftop nesting. At the same time, opportunities to use these makeshift habitats are dwindling as beachlike gravel roofs are replaced with synthetic materials that improve energy efficiency but are unsuitable for nesting. Regardless of whether birds nest on a beach or a building, scientists and volunteers want to do what they can to keep the colonies safe. “Having as many options as we can for these birds is the most important thing,” St. Germain-Vermillion says. 

Audubon chapters in Florida have watched over rooftop colonies—often first spotted by community members—for around a decade. At participating buildings, Audubon Florida staff install fencing to prevent falls, shelters that provide shade and refuge from predation, and game cameras to keep a close eye on the nests. Volunteers conduct regular surveys to estimate a site’s population and return any fallen hatchlings to roofs, equipped for the task with extendable poles topped with half an orange-juice carton (a custom contraption they call a “chick-a-boom”).

Since the birds often return to nest in the same place each year, gaining buy-in from building managers is essential. Kara Cook, an Audubon Florida rooftop biologist, monitored 30 active sites in the Tampa region last year. She reaches out to managers to inform them about the federally protected birds they’re hosting and asks for their cooperation. Many businesses are excited to help, she says. Others, like high-end car dealers or grocery stores, tend to be less enthused. “Which makes sense,” Cook concedes. “The birds poop a lot.”

To thank the New Orleans managers who provide access to their roofs, St. Germain-Vermillion presents each with a plaque featuring a photo of an adorable roof-hatched chick. The program began as a pilot in 2023 when Orleans Audubon Society shared concerns with Audubon Delta about the loss of gravel rooftops suitable for nesting birds. With the chapter’s help, St. Germain-Vermillion identified four active roofs and gained permission to monitor three. This year, assisted by volunteers, she’s keeping tabs on those colonies and continuing to look for others. 

Just as they would for beach-dwelling birds, Cook and St. Germain-Vermillion track how many rooftop nests hatch chicks and how many of those chicks survive to fledge. They hope that if they can identify what causes nests to fail, they can intervene to boost success now and improve—or create—future breeding sites.

How these rooftop colonies will weather coming challenges remains uncertain, but the birds have proven resilient in the face of changing conditions. Roof-hatched chicks can reverse course if needed, going on to nest on beaches as adults—as long as they have suitable habitat—according to research by Eckerd College conservation biologist Beth Forys, who has collaborated with Audubon Florida. “It’s amazing,” she says. “They’re very, very adaptable.”

This story ran in the Summer 2024 issue as “Friends in High Places.” To receive our print magazine, become a member by making a donation today.