In just a few miles an observer can travel from a tropical rain forest to the sub-tropical dry forest ecosystem.
Coral reefs, mangrove swamps, gorgeous rivers and streams, forested and herbaceous wetlands are within the most prominent ecosystems in the Caribbean Islands.
Many birds find their way to the refuge while migrating between North and South America including the Praire Warbler; Northern Parula and Cape May Warbler.
These birds use the refuge during the cooler months, while resident species including the Puerto Rican Tody, Adelaide's Warbler; Caribbean Elaenia, Troupial and the endabgered Yellow-shouldered Blackbird are here year round.
Historically, almost half the birds recorded in Puerto Rico have been observed in the lagoon and adjcent hills.
Visitors have a good chance of seeing a Magnificent Frigatebird, several species of herons, Smooth -billed Ani and occasionally the Yellow-shouldered Blackbird.