The Swan Islands, three tiny outcroppings of petrified reef jutting out of the otherwise open stretch of water between Cuba, the Cayman Islands, and Honduras, hold one of the least-known populations of Anolis in the Caribbean. A visit by George Nelson in 1912 established that anoles are present on both the larger Great Swan Island (larger is a relative term – the entire island is about 5.5 square kilometers) and Little Swan (which is about half that size). The specimens collected by Nelson were later examined by Barbour at the Museum of Comparative Zoology at Harvard and found to be closely related to A. sagrei – they were designated as a species, A. nelsoni, notable mainly for its exceptionally large size. They were later relegated to a subspecies of A. sagrei by Ruibal.
Aside from a visit by Brad Lister in the early 70s, the anoles of the Swan Islands have been left in relative peace by anolologists. That is, until last December, when I joined a team including Jonathan Losos, Randy McCranie and Leo Valdes Orellana that set out to visit the Swan Islands to learn more about this mysterious member of the anole clan.
Getting to the Swan Islands turns out to me much easier said than done. The island has been uninhabited for decades, except for a handful of rotating members of the Honduran Navy who are stationed there to keep drug smugglers from using the island as a way station. The only way to contact the island is by radio, with the cooperation of the Honduran Navy. The only way to reach the island is by chartering a private plane or boat. And getting permission to fly there required a week of wrangling with the authorities in La Ceiba, Honduras. With the help of local contacts in the police and the intervention of a lawyer, we were ultimately able to get the necessary permission, first from the head of the armed forces for all of Honduras, and then by the heads of the Air Force and the Navy, respectively. Once we had permission, we managed to charter a small plane to the island, stocked up on rice, beans, water and batteries (the islands have no electricity or running water), and were ready to go (minus Jonathan, who couldn’t last out the wait for permits and had to return to the U.S. to grade final papers).
Big Swan Island
Our first view of the island from the air revealed rugged cliffs and open beaches, dense forest, and decaying buildings overgrown by vegetation. We landed on the grassy runway that dominates at least a quarter of the area of the larger island and were greeted by seven armed members of the Honduran Navy and one friendly dog. Despite the guns, the Navy was very welcoming and helpfully carried many of our supplies to the main camp, where they had barracks and a kitchen, and where we could work at an indoor picnic table and could pitch our tents. After some minimal unpacking and setting up, we set off to get a feel for the island.
The forests in the center of the island are dark and dense. Walking short distances takes a long time, as you weave through interlaced branches, vines, and spider webs. The occasional clearing is full of thick, flourishing vegetation, sometimes innocuous vines covered in purple flowers, sometimes with feathery vines hiding needle-sharp hooked thorns. Later, when my arms and legs started to swell with painful blisters, I realized that the forests were also seeded with poisonwood.
The edges of the island alternate between crumbling jagged cliffs and empty stretches of beach. The cliffs housed resident populations of green iguanas, in much greater numbers than in the interior of the island. When approached, these grizzled creatures did not hesitate to dive into the ocean and to swim underwater away from the shore. The iguanas shared the shore with abundant curly-tailed lizards, who also occurred anywhere on the island where there was a break in the vegetation. The island is also home to an endemic species of agouti (I saw these shy rodents twice, while sitting quietly observing the behavior of anoles) and a large nesting population of brown boobies. Magnificent frigatebirds often flew overhead, but never seemed to get too close to the land.
Unfortunately, several introduced species have also gained a toehold here. I saw rats running through the brush around the buildings a couple times. My companions observed several cats prowling the area at night. And the walls of the buildings seemed to hold an endless supply of house geckos. It seemed, however, that all of these species were less common in the island’s interior.
But what about the anoles? You’ll have to wait for installment 2 to find out!