provided to The Santiva Chronicle
The state-threatened least terns had a big success this year on the Sanibel Causeway Islands, producing more nests and chicks in this location than they had since at least the 1990s, the Sanibel Captiva Conservation announced this week.
At the peak of nesting, SCCF said 142 least tern nests were incubating, with 114 chicks in the colony.
SCCF said the black skimmers, which also historically nest on the Causeway Islands, returned to the area this year, too. Approximately 30 black skimmers joined the least tern colony in mid-June. Although SCCF documented seven nests, no chicks were ever confirmed.
“Nesting colonies are dynamic in nature, with new nests still being laid as older chicks are fledging and leaving the colony,” said SCCF Shorebird Biologist Audrey Albrecht. “It is estimated that there were over 200 nests, fledging over 150 chicks. The earliest chicks fledged in May, and the last chick took flight on Aug. 2.”
The least terns and black skimmers regularly attempted nesting on the Cuaseway Islands after the bridge was built in the 1960s. Unfortunately, vehicle traffic and summer storms left most nests unsuccessful.
“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,” Albrecht said.
“To the best of our knowledge, 2023 was the first time least terns had tried to nest on the Causeway in at least 30 years, and 2025 is the most successful year since then,” she said.
Least terns likely returned to the Sanibel Causeway in 2023 due to the blank canvas of open sand created by Hurricane Ian reconstruction efforts, she added.
Least terns are colonial nesters, meaning they nest in large groups as a strategy to protect eggs and deter predators. These migratory seabirds arrive in Southwest Florida in April and depart in August, and they require large, open areas to nest.
In 2024, least terns returned to the Causeway once more, and this time successfully fledged at least 30 chicks. In 2023 and 2024, SCCF worked closely with the Florida Department of Transportation and the Florida Fish & Wildlife Conservation Commission to protect the colony and nests while allowing essential restoration work to continue.
This year, SCCF biologists noticed least terns exhibiting nesting behavior on the Causeway right before the Causeway Islands opened to the public for the first time in two and a half years.
“We immediately contacted FWC and Lee County staff to notify them of the nesting and worked together to rope off the nesting area in advance of the park’s opening on May 1,” Albrecht said.
“Least tern eggs are extremely well camouflaged, making it vital to protect nesting areas from pedestrian and parking traffic,” she said.
SCCF also started a volunteer shorebird steward program to station education and outreach volunteers near the colony during peak weekend beach times.
SCCF staff and more than 30 volunteers interacted with several hundred beachgoers throughout the season, offering information about the birds and a chance to view them up close with the spotting scope.