Puerto Rico and the US Virgin Islands are home to 29 endangered animals and 49 endangered plants presently. I say presently because more species may be endangered by continued human activity and more species may be found to be endangered as more biologists investigate the area.
In Vieques a number of endangered animals are frequently seen on the UNK trips. These include Green sea turtles, brown pelican, and leatherback sea turtle. While snorkeling students and I have seen barracuda, dolphin, squid (which look very unusual and colorful in their native surroundings), turtles, spotted rays, eagle rays, as well as the ‘normal’ contingency of reef fishes and invertebrates such as sea stars, sea cucumbers, and shrimps.
UNK students have participated in explorations for the Virgin Island tree boa and sea turtle nests. Other researchers on Vieques have discovered an endangered tree that was thought to occur only on Puerto Rico. More of these trees are being recorded and discovered with further work.
The West Indian manatee is known to inhabit the waters of Vieques. However these animals are rare, they prefer shallow areas with sea grass meadows and these areas are also attractive to people for recreational use and this is a problem of course. Manatee sightings are rare and so far we have not seen one on our trips to Vieques.
Other researchers have done herpetological surveys of Vieques, the imported green iguana and mongoose are impacting the native herps. I am sure the Vieques FWS would be happy to have more people survey their refuge for herp-tile populations. At this link is a complete list of endangered animals in Puerto Rico and US Virgin Islands.