Biological Reserve (Isla de Pajaros)These two small islands were set aside as a biological reserve in 1973. Their 143.5 hectares are primarily for the preservation of sea bird nesting areas. The island of Guayabo is especially known for having one of the most important nesting grounds of the brown pelican.

      These islands are often lumped together with the Isla de Parjaros Biological Reserve. This later island, made a biological reserve in 1976, with 4 hectares of area, has the same reason to exist as do the other islands, as protection to sea bird nesting sites.