To sweep the surface of a 2-acre offshore sandbar at the mouth of Mobile Bay for their Fourth of July fun, a group of volleyball players unthinkingly plucked the eggs from the simple sand nests of a large colony of least terns, likely killing more than 100 birds before they had a chance to hatch. That’s the only explanation Katie Barnes, the chief biologist for Audubon Birmingham’s Coastal Program, has for the discovery she calls no less than a tragedy.
On July 10, Emma Rhodes and Andrew Haffenden from the organization were checking for breeding activity on Sand Island, a spit of land completely separated from the larger Dauphin Island off the coast of Alabama. They were elated with what they saw — something like 600 sand nests, which experts say would make it the largest in the state.
But when they looked closer, they found a disturbing sight: Hundreds of eggs had been removed. Not only that, at least 30 of the grape-sized speckled eggs them had been stacked in small piles or used to decorate small sand dunes, then left on the hot sand to bake.
The two Audubon Birmingham Coastal Program survey workers also saw signs of human activity — abandoned plastic tent poles and a volleyball net still standing where the Fourth of July partiers had erected it.
“It’s really hard to imagine how someone could do that to a little egg,” Barnes said in a story on the Audubon Birmingham website.
Least terns, as the species’ name suggests, are the smallest of the tern family of seabirds and are about half the size of a cardinal. Their very existence is precarious, and they’re federally protected under the Migratory Bird Treaty Act. To survive predatory threats, their evolutionary strategy is to nest in dense colonies, spacing their sand nests a foot or so apart. That’s also what led them to Sand Island.
Completely disconnected from the mainland, the sandbar offers ideal habitat and protection for beach nesters. They are free from land predators like the foxes and feral cats that live on the larger island, but they still face threats from avian predators like laughing gulls and natural disasters like storm surges and high tides, which can wipe out dozens of nests.
Some of the speckled, grape-sized eggs Rhodes and Haffenden found on the beach showed signs of pipping — tiny cracks made in the shell as the baby bird pecks its way free. What is “really sad,” Barnes said, is that “there was a bird still trying to incubate her egg in that pile.”
Rhodes and Haffenden counted at least 100 abandoned nests, which Audubon Birmingham says is likely an underestimate because they didn’t want to disturb the colony. Some nests had as many as three eggs that had baked in the sand. Parents shield their eggs from the hot sun with their bodies, but they flew away when the volleyball players arrived, according to the report.
Mobile Bay is on the same latitude as Cairo and the Sahara Desert, so the brutal heat can be deadly in a matter of minutes for chicks growing inside the eggs, according to Roger Clay, a wildlife biologist for the Alabama Department of Conservation and Natural Resources.
“The thing about the eggs, people think, ‘oh, they’re eggs,’ but they are also almost fully formed chicks inside. They can walk almost as soon as they hatch,” Haffenden told Al.com’s Ben Raines.
“In that pile of eggs, there were a number that were about to hatch. … What the people did was take those eggs away from the protection of the parents from the sun. So we had dozens of functional chicks die by being baked. It’s pretty nasty.”
Haffenden, a wildlife researcher in Australia before he joined the Audubon Birmingham Coastal Program, said it wasn’t just human activity on the tiny beach that likely caused at 200 females to fly off their nests, “which certainly caused the death of their hatchlings, and about to hatch and developing eggs.”
“There were 17 boats on that tiny island,” he said.
Audubon Birmingham’s Coastal Program, whose funding is tied to the BP oil spill, reported the incident to the U.S. Fish and Wildlife Service, which is investigating. Barnes also called on state conservation agency to add the sandbar to its patrol area.
The day after the discovery, the area was fenced off and federal Fish and Wildlife Service signs were posted. There have been no signs of human activity since, Barnes said.
When she and her team visited the sandbar later, they were surprised to see so birds, as many as 1,200, still sitting on their eggs. Nesting, which typically happens in May or June with hatchlings emerging in July, was delayed this year.
Some of the nesting least terns may be late arrivals that didn’t find suitable nesting conditions elsewhere along the Alabama coastline, and some may be birds that started over after their nests were destroyed in the volleyball game, Barnes said.
But the losses from the volleyball game aren’t easily overcome, she said. As of early August, only 83 birds had fledged from around 600 nests and the least terns have moved off the sandbar. Some of fledglings were likely killed when high winds hit the area during the third week of July, swamping some of the nests that weren’t destroyed by the volleyball players.
Still, there’s reason for optimism.
“What we’ve heard from the state is that may be the largest least tern colony on record for the state of Alabama,” Barnes told the Al.com reporter. “Even with all the eggs that were lost, this site has still been a huge success for the birds. …
“It is a sand spit. There will be those natural occurences that kill birds. And there will be predation from laughing gulls and things like that. But, all in all, it was a success because these birds were able to raise their offspring.”
If they return next year — and whether they will is difficult to predict in the hurricane-prone Gulf of Mexico — Barnes and her group plan to fence the sandbar to prevent a similar occurrence.
She hopes the unthinking actions of the volleyball players will increase both awareness of the needs of beach-nesting words and respect for their boundaries.
“The take-home message is our protection helps birds, education helps birds,” Barnes said in the story on the website.
Photo by imageBROKER/Shutterstock
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