Look closely at the gravel rooftops dotting Florida’s beachfront buildings and you just might see shiny, wire “chick fencing” outlining their perimeters. With a pair of binoculars, you may spot a few wooden v-shaped structures dotted around the roof, creating shade and protection from predators.
These unlikely oases are important nesting areas for threatened shorebirds and seabirds, but are increasingly being replaced with greener materials. As beach nesting sites shrink and roofs are redone, wildlife managers help secure and expand habitats for the breeding birds.
The journey to the roofs
Least terns, black skimmers and American oystercatchers are among the birds driven to coastal rooftops to nest as their beach habitats shrink.
Researchers project 75% of the stretch of coastline from Cape Hatteras, North Carolina to West Palm Beach, Florida will have “very high erosion vulnerability” by 2030, up nearly a third from 2000. Sea level rise, more frequent storm surges and human disturbances provide additional challenges for the birds, which rely on sandy beaches to camouflage their eggs.
Volunteers and professionals work hard to secure beaches for the birds in Florida, roping off nesting sites and educating visitors, but shrinking beaches can be expensive, and sometimes, impossible, to reverse.
Coastal rooftops, on everything from Winn-Dixie to Dillard’s, offer another option.
About 43% of Florida’s least tern population, some 5,500 birds, nested on gravel rooftops across the state in 2023 according to data from the Florida Shorebird Alliance. About 16 American oystercatchers and 68 black skimmers did, too.
“They’ve kind of found that the [roofing] substrate is very similar to the rocky, shelly sand that they would nest in on the beach,” said Kara Durda, current Suncoast shorebird program manager and former regional rooftop nesting biologist with Audubon Florida.
The birds take up residence between Feb. 15 and Sept. 1, creating bowl-shaped “nest cups” in the roof’s pea gravel just as they would on the beach. Sometimes, the birds “decorate” their nests with pieces of wire or trash from HVAC repairs, Durda said, a substitute for the driftwood or shells they’d use on the beach.
As for rooftop birds’ reproduction, “clutch sizes, which is the number of eggs in each nest, and the number of flight capable young that are produced per-pair are similar to the ones that are documented at ground colonies,” said Hailey Dedmon, northeast and north central regional shorebird biologist with the Florida Fish and Wildlife Conservation Commission.
The elevated eggs are generally safe from the raccoons, foxes and coyotes that approach their ground-floor counterparts, but parents stay close by to incubate the eggs and fend off raptors or fish crows that may attack from above.
Once the eggs hatch, parents forage for small fish, mollusks and insects to feed their young, “taking advantage of whatever body of water is nearest them,” Dedmon said.
Beach-born chicks waddle alongside their parents to find food, but rooftop chicks, too young to fly, get dinner delivered. “We really want them to stay on the roof as long as possible because there's a risk of falling,” Durda said. “Usually they can’t get back up on the roof after they have left because their flight muscles just aren’t strong enough.”
Nesting monitors patrol the ground around rooftop sites for fallen chicks, returning them up with a “chick-a-boom”: a device invented by an Audubon volunteer. While members of the public shouldn’t touch fallen chicks, volunteers are trained to do so, carefully inserting them into a carton at the end of an extension pole and guiding the apparatus up the wall with a paint roller.
“It's a better option than us having to put up a ladder and then climbing the ladder with the chick in one hand,” Durda said, “likely disturbing the entire colony.”
It takes four to five weeks from hatching for the rooftop chicks to learn to fly, a process known as fledging. The chicks may stick around their parents for a few months after fledging, catching up on the foraging lessons they missed compared to their beach-nesting counterparts.
Rooftop replacements
While shorebirds occasionally nest on other types of roofs, they seem to significantly prefer gravel.
Coastal builders? Not as much.
The roofs are made by pushing gravel into an asphalt base and capping it with another layer of the rocks, leaving the top loose.
Wind gusts during Hurricane Katrina in 2005 blew pea gravel off a building’s roof in downtown New Orleans, breaking “the vast majority of windows” on the side of a nearby hotel.
International building code prohibited the material from being used in hurricane-prone regions the following year, but Florida delayed adoption of that section of the code, awaiting further studies.
International building code loosened its prohibition in 2021, instead requiring builders install perimeter walls known as parapets to contain the gravel. Today, Florida allows gravel rooftops with certain height and slope restrictions, but the material is losing popularity in favor of more energy-efficient alternatives.
Seven of eight roofing contractors in Pinellas County referred to gravel rooftops as “obsolete” as early as 2002, according to researchers at Eckerd College.
About 100 gravel rooftop nesting sites in Florida were re-roofed to non-gravel materials between FWC’s 2007 and 2010 surveys. The five-county region Durda monitors around Tampa Bay had about 120 gravel rooftops in 2017. Last year, it had 56.
Staff and volunteers install chick fencing, signs and shade shelters to make the roofs that remain as safe as possible for the birds, but recognize “eventually these rooftops aren't going to be here,” Durda said. “We have to be a little creative and think out of the box for how we can continue providing them a space to nest that is suitable and safe.”
Alternative nesting sites
Most rooftop nesting birds aren’t banded, so it’s hard to track where they go when roofs are replaced.
In Pinellas County, “there's still enough gravel roofs out there that they just find another one,” Durda said, noting she has never seen a banded bird switch from nesting on a rooftop to a beach.
Dedmon said displaced birds in Brevard County, too, likely go to other gravel rooftops nearby, though she’s observed some least terns making the switch to quiet, cleared construction sites with sandy or gravelly ground.
Beth Forys, a professor of Environmental Science and Biology at Eckerd College, designs other places for the birds to go.
Forys installed boxes of gravel on the Weedon Island nature center when it was reroofed in 2006, but birds never came. She stationed two 45-foot, gravel-covered rafts in Fort DeSoto lagoon in 2010, complete with painted decoy birds to recruit least terns. “It's a colonial species,” Forys said. “They'll try new areas, but they like to see somebody else there first.”
Least terns approached the raft hesitantly in the first two years, the few that tried to nest abandoned the site quickly. Twenty pairs nested on the rafts in 2012, at least 14 of their chicks reaching the flight stage.
“This level of productivity is greater than any other ground colony in the Tampa and Sarasota Bay regions monitored during the past ten years,” Forys wrote in a conference summary of the study. “While this study was relatively limited in time and number of birds, it indicated that rafts should be considered as a management strategy to provide nesting areas as gravel rooftops are phased out.”
Researchers in Poland successfully used similar rafts as nesting sites for common terns, concluding the rafts may be a helpful conservation tool in areas where natural habitats have disappeared.
“People were offended by the idea of the raft,” Forys said. “They were worried that the raft represented not putting enough effort into the beaches.”
Forys maintains that protecting existing beach sites is the first priority “but I think where we look to the platforms is if our beaches are starting to get overwashed.”
Durda echoed that creative nesting solutions will continue to gain importance as shorebirds’ natural and rooftop habitats shrink.
“ Ideally they would be back on the beach,” she said. “If we continue to see coastal erosion, you know, that might not be a viable option.”
