Shorebird monitor Sue Leitholf could hear the least terns’ high-pitched din through the low rumble of the boat carrying her to an isolated sandbar off Cape Romano.
“Hey guys, we’re back,” Leitholf, an environmental specialist with Rookery Bay National Estuarine Research Reserve, said Thursday as she hopped off the boat, binoculars around her neck and clicker counter in hand.
Nicknamed Second Chance by monitors in the mid-’90s, the mound of sand and shell that has come and gone over the decades is back this spring — big time.
Monitors estimate that 800 least terns have landed at Second Chance, a record for the ephemeral sandbar and the largest nesting colony of the threatened species anywhere in South Florida or the Florida Keys. The birds have laid tiny well-camouflaged eggs in 400 nests, or scrapes, on top of the sand.
That compares to almost 300 least tern nests so far in Lee County and makes up the bulk of the 600 least tern nests in Collier, according to Florida Fish and Wildlife Conservation Comission estimates.
The terns began arriving in April, returning from their wintering grounds in Central and South America. When they spied Second Chance, they couldn’t resist it.
“That’s the place to be for the terns,” Conservation Commission regional biologist Ricardo Zambrano said.
The long, narrow, crescent-shaped sandbar has more appeal to a nesting shorebird than other popular nesting beaches on Marco Island and on Fort Myers Beach, he said.
First, it’s surrounded by water, making it safer from land-based predators like raccoons. It also has low vegetation to shade chicks. The sandbar’s height means it is more difficult for waves to overwash the nests.
At four acres, it’s also big and, when it comes to shorebird colonies, the bigger the better. Larger colonies are better able to team up to fight off predators, including those from the air, like ospreys.
An osprey perched ominously Thursday atop one of the stakes marking the edge of the off-limits nesting area, just yards from still-wobbly chicks.
The least terns at Second Chance are bucking a statewide trend toward “micro-colonies,” said Brie Ochoa, assistant biologist for the Conservation Commission region that includes Lee County.
All across Florida, smaller nesting colonies are growing in number as large nesting sites either disappear or decline in habitat value, she said.
Leitholf and members of Rookery Bay’s volunteer group, Team OCEAN, make weekly trips to Second Chance to keep tabs on the colony.
On Thursday, volunteer Tom McGrath piloted the boat; volunteer Barb Leitholf, Sue’s mother, and volunteer Jim Truluck carried a Ziploc bag of colored twine to restring the flagged edges of the nesting area.
The sandbar was abuzz with birds protecting their spot on the sand and making nonstop flights off the island and back with a wriggling baby fish in its beak for a partner or young.
Leitholf, the environmental specialist, walked down the edge of the nesting area, separating it into imaginary quadrants. As she went along, she would wait for the birds to settle to start counting the next spot, speaking into a handheld tape recorder to note the tally.
“Wow, kindergarten over there,” Leitholf said, referring to her pet name for a bunch of baby least terns.
Thursday’s tally: 243 least tern chicks, about 10 least tern nests left to hatch — and some surprises. Leitholf counted about 35 adult black skimmers and 19 chicks, a big jump since last week’s monitoring trip, she said.
No skimmers nested at Second Chance last year, and monitors weren’t sure the skimmers were nesting there this year either.
“Now we know they were,” she said.
The nesting activity will wrap up by the end of August, coinciding with the heart of hurricane season. With vegetation covering more of the sandbar, it might be better able to ride out some storms that have washed it away in the past.
Only time will tell what least terns will find on their return trip to Second Chance.
Connect with Eric Staats at www.naplesnews.com/staff/eric_staats