Tom Morris is a biologist and diver who lives in Gainesville, Florida and turned 70 years old on this expedition. His birthday present was a passport that he left in his car before heading across the Florida Straits by boat to join the team. He can now leave the Bahamas when the time comes, although he would rather remain in the Bahamas, where the pines sing, the bracken is tall, and every other plant is an aphrodisiac.
At its closest point, the Bahama Archipelago is a mere 50 miles from Florida, but it has virtually nothing in common with continental mainland animals, except for the ones that can fly (birds and bats). In fact, the only native land mammal found naturally in the Bahamas is the hutia, which is of South American origin. And there are only three species of snakes, all boas and probably descendants of a common ancestor, also of South American origin. The same pattern holds true for frogs and lizards, and even insects. So how is it that the archipelago is so biologically isolated from North America?
Some animal groups, notably the reptiles, with their waterproof skin and low metabolic rates, are able to survive relatively lengthy ocean crossings – think Galapagos and Seychelles Island tortoises and Komodo dragons. And I have personally seen diamondback rattlesnakes, which were at one time numerous on Florida’s barrier islands, floating miles out in both the Gulf of Mexico and the Atlantic Ocean, apparently none the worse for wear. But an animal floating or riding a log from Florida has to overcome two big obstacles to make it to the Bahamas; the trade winds and the Gulf Stream.
The trade winds are planetary winds, the largest and most consistent winds on earth, and the Bahamas lie directly in their path. The trades blow from an easterly direction over two-thirds of the time, pushing floating objects towards the mainland.
The wind blows from the west less than ten percent of the time. and is generally much weaker than the easterlies. But, even if favorable winds push a drifting animal towards the Bahamas, it will soon find itself in the Gulf Stream, and moving north at up to six miles per hour, toward the open Atlantic and almost certain death.
Animals and plants on islands have historical extinction rates far greater than their continental cousins. Everyone is familiar with the fate of many isolated island inhabitants, such as the flightless birds of New Zealand, who evolved in the absence of mammalian predators, and could not cope with human introduced rats, cats, pigs, and other animals. The Bahamian fauna face similar threats. The only animals I have seen dead on the Abaco roads have been cats and raccoons. Both invasive species are known to kill local animals, including the threatened Abaco parrot. And, perhaps more tragic, a scale insect from the mainland, brought in on Christmas trees from the mainland, are destroying the native Bahamian forests of Caicos Island.
But on a more positive note, the local newspaper, The Abaconian, reported today that a pregnant manatee from Florida, named Washburn, has been tracked crossing the Gulf Stream, and is now swimming in the waters of the northern Bahamas near Walker’s Cay (pronounced “key”). She arrived on Thanksgiving day. This is the same gal who was rescued from the cooling waters of Cape Cod, Massachusetts. Ain’t no trade winds or Gulf Stream gonna keep this girl from going where she wants to.