Barro Colorado (1,500 ha), the largest island in Lake Gatún, was isolated when the Chagres River was dammed to form the central part of the Panama Canal in 1914. The Nature Monument includes the island and five adjacent mainland peninsulas, Bohio, Buenavista and Frijoles to the east, Gigante to the south, and Peña Blanca to the west, as well as several smaller islands. The Bohio and Buenavista peninsulas are contiguous with Soberania National Park. The area contains semideciduous lowland forest, with old growth forest at least 500 years old on the southern and western parts of Barro Colorado and younger forest 70-120 years old on the rest of the island and on the peninsulas. There is a large scientific research station on the island and a smaller substation on the Gigante peninsula, as well as an extensive trail system. The mainland area to the south and west of the monument is inhabited by farmers and devoted to cattle and subsistence agriculture.
More than 20,000 soaring raptors have been counted on migration in 2004, including Turkey vulture (19,068), Broad-winged Hawk (14,860), and Swainson's Hawk (2,756). More probably occur, since the observation point did not cover the entire reserve. The globally near-threatened Great Curassow has been recorded but is very rare. Because the island is protected from hunting, it has the densest population of the nationally threatened Crested Guan in the Canal Area. Sulphur-rumped Tanager, an endemic of the Central American Caribbean Lowlands and Darien Lowlands EBAs, also occurs. Since its isolation between 50-90 of the bird species originally found on the island have become extinct there (Willis 1974, Robinson 1999). Some of these local extinctions were due to loss of species typical of second growth as younger forest matured, but at least 70 appear to have been due to isolation alone (Robinson 1999). Barro Colorado is one of the best-documented examples of loss of species in isolated forest fragments over time.
Non-bird biodiversity: The area has been identified as a Key Biodiversity Area (Angehr 2007) due to the occurrence of several threatened plants, as well as American Crocodile, Baird's Tapir, Central American Woolly Opossum, and West Indian Manatee.
BirdLife International (2022) Important Bird Areas factsheet: Barro Colorado Nature Monument. Downloaded from http://www.birdlife.org on 09/08/2022.