Feed the Cannibal Fish Cedar Point

The birds that mysteriously disappeared from an island off Cedar Key last year still have not returned, and now the cottonmouth snakes there are cannibalizing each other.

Other than that, everything is just peachy these days on Seahorse Key.

Last year, tens of thousands of birds abandoned their nests in an ongoing ecological mystery. Lots of theories — from secret military flights to diseases — have been proposed, but no consensus has emerged. Interestingly, the birds nesting on nearby islands have not been disturbed.

The brown pelicans, various herons and egrets, ibis, roseate spoonbills and cormorants that used to nest on the small island had a unique relationship with the venomous cottonmouth water moccasins.

The birds would catch and eat fish, and fish bits would then fall from the nests. The snakes hung out below and had meals literally fall from the sky. In turn, the snakes would leave the nests — and the birds' eggs — alone.

This spring, with the flocks of nesting birds and their main food source gone, the snakes have become famished.

In desperation, they have taken to eating other cottonmouths, said Coleman Sheehy, a University of Florida researcher who specializes in reptiles and amphibians.

"We're now seeing evidence of cannibalism,'' Sheehy said. "They are looking for whatever that can find and if it's their next-door neighbor, they'll eat their neighbor as well. It's a rough world out there.

"We are seeing their body condition appear to be decreasing,'' he said. "They are skinnier. And we see more dead snakes than in previous years. They are moving around more, presumably because they are hungry and looking for food.''

While the snakes on Seahorse Key are a menace to each other, they remain unnaturally placid toward people. Cottonmouths earned their name for gaping their white, fanged mouths wide in a display of fearsomeness when threatened — sometimes hissing for added effect.

But Wednesday afternoon, as UF grad student and snake researcher Mark Sandfoss released cottonmouths that had been captured on the island and taken to Gainesville for measurement and microchipping, they showed no defensiveness at all.

Sheehy said he witnessed cottonmouths eating each other — the aggressor biting the victim, poisoning it with venom and swallowing it whole. A cottonmouth is not immune to cottonmouth venom.

Water moccasins can grow to between 4 and 5 feet long, though most are smaller, and weigh about 3 kilograms.

Meanwhile, the moccasins on Snake Key — an island about 3 miles from Seahorse Key to which some of the birds migrated last year — are getting as chunky as the cottonmouths on Seahorse were when they were able to gorge on fish droppings, Sheehy said.

"The ones on Snake Key have very good body condition. They are obviously very fat," he said. "It's very concerning that the birds left Seahorse because that is a long-term, important nesting colony.

"For the snake population, it's also a concern. The silver lining is that it's created a natural experiment for us to look at what's happening and monitor the effect of a major transition."

Vic Doig of the Cedar Keys and Lower Suwannee national wildlife refuges said the birds have not returned to Seahorse to nest this year.

After last year's abandonment, some of those birds went to Snake Key and nested, joining avians that had raised chicks there before. Those Seahorse transplants likely returned to Snake again this year.

Refuge staff are still hoping the birds will return to Seahorse, but Doig added it probably won't be this year.

"Most of the species are just starting to nest and it doesn't look like they are going back to Seahorse Key, which kind of stinks because there is a lot more room — you can fit a lot more of them on Seahorse," Doig said. "We put out nesting decoys to try to lure them back, but so far nothing is working. At least the birds are going to nest at Snake Key."

Seahorse Key, roughly a mile long and half-mile wide, is about 4 miles southwest of Cedar Key and was the largest bird rookery along the Gulf coast.

In the mid-1800s, the island was a way station for Seminoles captured in the Second Seminole War before they were moved elsewhere.

A lighthouse was built in 1843 on what stands as the highest point along the gulf — 52 feet above sea level. Today, it's a UF marine lab. Other than that building, Seahorse Key is left to the birds, snakes, occasional raccoon and other small animals.

The birds, about 15 species in all, sudden flew off around April 20, leaving their nests behind.

A year has passed with no explanation.

Lack of food was not an issue and tests for parasites or disease were negative. It has since been learned that helicopters from the Department of Homeland Security's Customs and Border Patrol had flown over the area at night around that time, but that has not been determined to be the cause.

The wildlife refuge is now working with federal agencies to get a designation for large nesting colonies with temporary flight restrictions with notices going out about the restrictions.

While boaters will sometimes come to the few sandy beaches on the island or explore its bays, it is off-limits during nesting season. All of Seahorse Key, including the beach and a 300-foot buffer around the island, is closed to public access from March 1 through June 30.

Experts say it was likely the abandonment was caused by a human disturbance of some sort, one so frightening that the birds left and haven't come back.

They may never come back, but future generations might.

"If it was some sort of traumatic disturbance, there would probably be some sort of memory and the birds don't want to go back. That could be generational," Doig said.

"I wouldn't think there is enough room for them at Snake Key but they are pretty good at cramming themselves in like sardines. They start nesting three-dimensionally. The pelicans haven't started nesting yet, and they are going to find there is no room left at Snake Key."

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Source: https://www.gainesville.com/story/news/local/2016/04/07/cannibal-snakes-deepen-cedar-key/31893305007/

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