TAMPA — The first couples arrived on the beach earlier this month. They staked out sandy spots and chattered and warned each other when hawks flew overhead.
Any day now, they will mate.
Nesting season for migratory birds starts April 1, but American oystercatchers typically start early. They're monogamous for life and tend to return each year to nest on the same beach.
For about 80 pairs of the large, conspicuous white birds with orange beaks, home is two protected islands in Hillsborough Bay, just off Tampa's shores and not far from MacDill Air Force Base.
The Tampa Port Authority inadvertently created the bird sanctuaries decades ago, as a means to relocate soil dredged from the bay. Today, the islands serve as a substitute home for oystercatchers and other birds displaced from coastal beaches by human activity.
"They're one of the rarest birds in Florida," said Ann Paul, a biologist for Audubon of Florida, which protects the islands' oystercatchers and more than a dozen other nesting species. "As the islands warm, it becomes a grand crescendo of bird activity."
Tens of thousands of migratory birds will nest on the islands, which span about 500 acres each, before the season ends in August. To keep their eggs safe, signs dot the beaches warning boaters to stay off.
But often they don't, so Paul and other Audubon workers patrol the area by boat.
They chase off families with picnic baskets, kids with dirt bikes and even nude sunbathers.
Once, two illegal immigrants jumped from a freighter and swam to shore.
Another time, a couple landed from a helicopter. The man, who had planned a romantic proposal on a deserted island, instead found an inhospitable wilderness and an irate Audubon staffer.
And then there was a group of teens who came to film a movie. Their toy machine guns warranted a call to officials.
Years back, visiting boaters made bonfires with the "no trespassing" signs, which were made of wood. Now they are metal.
If boaters won't leave, those patrolling call the county Sheriff's Office. Penalties can be stiff. Killing an endangered species can warrant an arrest and felony charge.
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It wasn't always this way. The Port Authority created the islands, just a couple of wing flaps apart, between 1978 and 1982. Officials needed some place to dump the sandy silt dredged from the bottom of ships' paths and eventually called the spoils "Island 2D" and "Island 3D."
In no time, migratory birds began to settle here, including oystercatchers.
Audubon, a nongovernmental agency, had been protecting waterbirds in the bay since 1934 and predicted the islands would become valuable nesting ground.They began patrolling right away.
They can't enforce the federal Migratory Bird Protection law, but do pass out informational pamphlets to wayward trespassers, contact authorities when necessary, and keep tabs on water activity, such as dredging procedures, to ensure the birds are safe.
The port still uses the islands as dumps for silt from the bay's bottom. That keeps large vegetation, such as trees, from growing there. Earlier this month Phillip Steadham, the port environmental director, met with contractors who pipe dredged soil onto the islands, Audubon workers and other regulatory officials to prepare for this year's nesting season.
His duties include getting the word out to recreational boaters.
"People love to take their dogs and picnic baskets out there. It's very quiet," he said. They often wonder: "Why are you making such a big fuss about these birds?"
Steadham explains that the oystercatchers need to nest on beaches and are very territorial, actually marking lines in the sand. Although thousands of birds will nest on the islands, oystercatchers will be a minority. Only 400 pairs remain in Florida, where they are classified as a species of special concern. The islands also draw a large colony of laughing gulls and a few least terns, which are classified as threatened.
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Fewer people would land on the islands if they knew about the rampant rattlesnake population, say those who know. Audubon workers explain the danger of rattlesnakes, as well as the birds' plight, to clueless boaters.
In mid March, Mark Rachal, a coastal island sanctuary manager for Audubon, saw the arrival of the first oystercatchers for the season. He was circling an island in his boat again Tuesday, marking additional pairs on a scorecard. They typically take a couple of weeks to establish their territory before mating.
Rachal has patrolled the islands since 2006 and knows where to expect nests.
"They're faithful to each other and to their sites," he said, adding that some come back to the same spot for as long as two decades.
A female will lay one egg per day over three days, just above the tide line. Then she and her mate take turns sitting on the eggs for 26 days. While one sits on the eggs, the other, called the "sentinel," stands on the shore watching for predators.
On a recent boat patrol, a hawk flew overhead and two oystercatchers sounded a rapid-fire "cheep!" darting off and over the bay in front of Rachal's boat.
Onshore, he has chased a roaming dog that stepped into a nest between two eggs and a man with a chain saw who was cutting pieces of driftwood.
Other dangers include tides from storms or cruise ships that can wash an egg or chick out to sea. Boaters milling along the shoreline, perhaps fishing, can cause the birds to abandon their nests.
When a boat nears, oystercatchers often flee the nest, leaving behind their camouflaged gray and black mottled eggs. Without a parent there to shield it from the sun, the chick inside can die in 15 minutes on a hot day.
If they die, then the couple lay another batch. Eggs that haven't hatched by July 4 have little chance, though, Rachal said.
It's this fragile, yet persistent existence that Rachal respects.
"You kind of get a relationship with them," he said. "You see three chicks. Then you see two chicks. Then you see one chick and you think, just hold on."
Rarely do all three survive.
During that boat trip, he counted 16 couples on the island. Some were mating, others marking their territory. Five already were tending eggs.
Elisabeth Parker can be reached at email@example.com or (813) 226-3431.