SCCF biologists recently located least tern (Sternula antillarum) nests on Sanibel and Captiva, which have been posted off to protect the birds from human disturbance. This is the first time they’ve nested on the islands since 2020.

Least terns — the smallest terns in the world — are state-threatened seabirds that can be found along Florida’s coasts during late spring and summer. These birds often nest close to other beach-nesting shorebirds and seabirds, including piping plovers (Charadrius melodus), snowy plovers (Charadrius nivosus), and black skimmers (Rhynchops niger).

“Unlike plovers and other shorebirds, seabirds like the least tern are colonial nesters, meaning they nest in groups and work together to defend their nests from predators,” said SCCF Shorebird Biologist Audrey Albrecht. “A nesting colony of least terns sounds like a chorus of squeaks, which may not sound too threatening, but they’re known to dive bomb and defecate upon anyone coming too close to their nests or chicks.”

Least terns typically nest on sandy shorelines along rivers, lakes, and the coast, but can also be found on gravel rooftops and near mining operations where there are large tailing ponds (which store byproducts of the mining process, including water, sand, clay, and dissolvible chemical compounds).

“At one point in Florida, nearly half the least tern population was nesting on rooftops,” Albrecht said. “As buildings replace these older style rooftops with newer ones, the availability of suitable rooftop habitat is decreasing.”

The history of least terns on Sanibel

When the Sanibel causeway was built in the early 1960s, both least terns and black skimmers nested on the causeway islands. Unfortunately, this led to many vehicle collisions with low-flying adults and flightless chicks.

For decades, conservationists from J.N. “Ding” Darling National Wildlife Refuge, the Sanibel-Captiva Audubon Society, SCCF, the Calusa Bird Club, and others worked to try and mitigate the losses. Despite their best efforts, hundreds of birds continued to be killed each year.

“Eventually fences were installed along the roadways, which minimized car collisions, but heavy rains running off the roadway sometimes caused nests and chicks to be washed out to sea,” Albrecht said. “Efforts were then made to attract these nesting birds to safer areas away from the causeway.”

By the 1990s, least terns had abandoned nesting attempts on the causeway, and they’ve been nesting on the beaches of Sanibel, Captiva, and Fort Myers Beach ever since.

Help protect least terns

Keep all our coastal wildlife safe, including shorebirds, seabirds, and sea turtles, by staying out of posted areas, picking up all trash, keeping pets leashed, and never feeding wildlife. Feeding gulls and crows attract them to nesting areas, putting eggs and chicks at risk. For more information about how you can help protect coastal wildlife, visit sancaplifesavers.org.