In 2015, tens of thousands of birds mysteriously abandoned their nests in Seahorse Key, an island off Cedar Key. 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 island is part of the Cedar Keys National Wildlife Refuge, and biologists investigating the bird disappearance say they still have no answers.
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.
What kind of cataclysm prompts thousands of birds to leave a season’s worth of eggs they’ve invested tremendous energy into laying and incubating?
One idea was put forth by Dr. Sheehy. He had noticed an increase in the number of raccoons on the island. Again, these isolated islands are selected for by nesting birds because of the lack of such predators and Dr. Harvey Lillywhite indicated that the typical number of raccoons on the island is zero. But Dr. Sheehy and Captain McCain had trapped and relocated seven raccoons earlier this summer. This suggests that a large group (large for this island) had found their way to Seahorse Key. Dr. Sheehy suggests that the cause of the movement of birds were the raccoons. There is no evidence of them attacking the birds but they believe the shear presence of the animals was enough for the birds to relocate. However Dr. Fredrick points out that (a) there was little evidence of the raccoons preying on the fallen eggs and (b) he could not find track or scat evidence of more than one or two raccoons on the island during his initial survey after the birds left. He is not so sure the raccoons were the cause.
One year later, this Florida island is experiencing another confounding event: Snakes are cannibalizing each other.
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.
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