The Sanibel Causeway is hosting some incredibly special seasonal residents once again. Coming off a highly successful 2025 season, the Sanibel-Captiva Conservation Foundation (SCCF) announced that state-threatened least terns have officially returned to nest on the causeway islands.
This marks the fourth consecutive year that these protected birds have claimed the causeway as a breeding ground following a prolonged 30-year absence from the site. Adding to the excitement, black skimmers—which successfully nested alongside the terns on the causeway islands last year—have also returned to establish their nests for the season.
At the LeAneSuarezGroup, we know that the vibrant, protected wildlife is a core part of what makes our coastal communities so deeply special. Seeing these vulnerable species reclaim historic nesting grounds is a true testament to the ongoing conservation efforts driving Southwest Florida’s ecosystem forward.
In a nutshell: State-threatened least terns and black skimmers have returned to the Sanibel Causeway for another critical nesting season. As of early June, the colony is thriving with dozens of nests under close supervision by the SCCF and state wildlife partners.
The Unique Dynamics of Colonial Nesters
Least terns are migratory seabirds that arrive in Southwest Florida every April and depart by August. They are strict colonial nesters, meaning they intentionally lay their eggs in large, synchronized groups to help deter local predators and collectively defend their territory. Because they require massive, open areas with minimal vegetation to scrape out their nests, the sandy expanses of our coastal environments are highly ideal—yet heavily vulnerable.
A Look at the Numbers (As of June 3, 2026):
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Least Terns: The terns began nesting right before Memorial Day weekend. There are approximately 80 adult least terns managing 40 active nests on the causeway islands.
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Black Skimmers: Roughly 60 adult black skimmers have integrated directly into the causeway colony alongside the terns.
Overcoming a Turbulent History on the Causeway
The return of these birds is a massive conservation victory when looking at the historical timeline. Following the original construction of the Sanibel Causeway in 1963, both least terns and black skimmers regularly attempted to nest on the newly formed islands. However, heavy summer storms and constant vehicle traffic historically decimated the colonies, leading to decades of failed nesting attempts.
“There are several newspaper articles detailing the struggles that least terns and black skimmers on the causeway historically faced from nest washovers and car strikes. Despite the best efforts of our local conservation organizations to protect them and lure them to other nesting sites away from the causeway, the birds continued to fall victim to traffic and the weather. They turned to other nearby beaches and rooftops but struggled to find suitable nesting habitat.” — Audrey Albrecht, SCCF Shorebird Biologist
The generational pattern finally broke in 2023 when the least terns successfully nested on the causeway for the first time in three decades, paving the way for 2025 to become an absolute banner year for the species.
A “Tern” of Events: Shifting Colonies & Predator Pressures
If you have driven past the causeway recently and noticed a slightly lower density of shorebirds than last summer, there is a fascinating ecological reason why. The terns have split their forces into three separate colonies across the region this year.
The SCCF coastal wildlife team is working diligently to monitor all three sites simultaneously, ensuring adequate protection as the fragile chicks begin to hatch. Shifting colony locations on the west end of Sanibel have been heavily influenced by coyote activity:
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West Gulf Colony: Initially started strong with 40 laid nests, but severe coyote depredation left only seven remaining as of June 3.
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Clam Bayou Colony: Originally documented 13 nests, dropped to four due to coyotes, rebounded beautifully back up to 21, and was sitting at about 10 active nests by June 3 following subsequent predator pressures.
Because of the intense, ongoing predator disruptions at the West Gulf and Clam Bayou beach fronts, biologists anticipate that least tern numbers on the protected causeway islands will continue to climb as the summer progresses.
To ensure these vulnerable nests remain safe from car strikes and human disruption, the SCCF works in close coordination with the Florida Department of Transportation (FDOT), the Florida Fish & Wildlife Conservation Commission (FWC), and Lee County. Please respect all posted wildlife signage and temporary fencing when visiting the causeway beaches this summer!
