Contributions to Avian Biogeography From the Archipelago and Lowlands of Bocas Del Toro, Panama

Abstract

-New distributional information is summarized from avifaunal surveys conducted from 1987 to 1991 in the ornithologically unknown islands of the province of Bocas del Toro, Panama, and points on the adjacent mainland. These establish the region of the Laguna de Chiriqui to be of great biogeographic interest and complexity. New records include 3 species new to Panama, and 11 species and 3 subspecies new to Bocas del Toro. Two taxa of birds (Platyrinchus cancrominus and a form of Chlorophanes spiza) are relicts on islands and are not resident on the Panamanian mainland. Four pairs of species or subspecies (Anthracothorax prevostiilA. veraguensis, Glaucis aenea/G. hirsuta, Gymnopithys bicolor olivascensIG. b. bicolor, and Tangara inornata rava /T. i. languens) are shown for the first time to change abruptly over a narrow distance along the southern shore of the Laguna de Chiriqui. Received 6 January 1992, accepted 22 April 1992. THE PROVINCE of Bocas del Toro occupies the western quarter of the Caribbean coast of Panama. Its most distinctive physiographic feature is a large embayment (Laguna de Chiriqui/Bahia de Almirante) encompassing many islands, some quite large (Fig. 1). Along the southern shore of this embayment, lowland habitats are very restricted because of the proximity of mountains to the sea. Other factors that may have biogeographic significance are the presence of a deep channel (20 to 30 fathoms) between the Valiente Peninsula and Cayo Agua, and an extensive area of swamp at the southeastern corner of the Laguna de Chiriqui. Systematic ornithological collecting in Bocas del Toro began in 1926 (Kennard and Peters 1928) and continued actively for a few years, but then fell off for a quarter century (Eisenmann 1957). Alexander Wetmore made substantial collections for the Smithsonian Institution in 1958, but with minor exceptions almost exclusively near Almirante. In the 1960s, the Gorgas Memorial Laboratory operated hundreds of mist nets near Almirante in connection with epidemiological research, which added considerably to ornithological knowledge of the