FAMILY PARULIDAE 



26l 



Adult female, like male, but paler, duller yellow throughout, and 

 reddish brown areas absent or fainter and reduced. 

 Immature, like female, but paler. 



The Yellow Warbler is the only member of its family represented in 

 Panama by both migrant and resident races. Dendroica petechia com- 

 prises three groups of subspecies that were once considered separate 

 species: the yellow-headed aestiva group (Yellow Warbler), which 

 is mainland North American in distribution and chiefly migratory, the 

 chestnut-capped petechia group (Golden Warbler) of the West Indies, 

 most of coastal Venezuela and Cozumel Island, and the chestnut- 

 hooded erithachorides group (Mangrove Warbler) of both coasts of 

 Central and South America to Peru on the Pacific side and to the Para- 

 guana Peninsula of Venezuela on the Atlantic side. Except when they 

 occur on relatively small islands, birds of the petechia and erithacho- 

 rides groups are usually confined to coastal mangrove swamps. Mi- 

 grants are widely distributed in the lowlands in semi-open areas and 

 gardens, as well as in mangroves. 



Recent works (e.g., Lowery and Monroe, in Peters, Check-list Birds 

 World, vol. 14, 1968, pp. 14-20) include the erithachorides and aestiva 

 groups in the species petechia. Large series of specimens from Pan- 

 ama and Colombia recently studied by Olson (Proc. Biol. Soc. Wash., 

 vol. 93, no. 2, 1980, pp. 473-480) corroborate this treatment. The 

 Yellow Warblers on the Pacific Coast from Panama to Peru exhibit a 

 gradation in plumage characters from birds of the chestnut-hooded 

 erithachorides group to those resembling the chestnut-capped petechia 

 group. The subspecies on the Galapagos and Cocos Island is presum- 

 ably derived from the erithachorides group, but is convergently similar 

 to the West Indian birds. 



The song, behavior, and diet of the resident races of the Yellow War- 

 bler are similar to those of North American forms, except that, as 

 noted, the former are usually confined to mangroves. The stomach of 

 a resident individual collected in the Canal Zone by E. A. Goldman on 

 May 30, 1911, contained 2 blunt caterpillar jaws 5%, 3 entire spider 

 eggs parasitized by a hymenopteran, and fragments of others 35%, a 

 tipulid 12%, head of a hymenopteran 1%, moth remains 1%, 14 heads 

 and other remains of ants 30%, a small chrysomelid 1%, weevil re- 

 mains 1%, 4 beetles (Nitidulidae, Colastus?) 5%, other coleoptera 9%. 

 Apparently these birds breed somewhat irregularly: of 2 adult males I 

 collected at La Honda, Los Santos, in March 1948, 1 was singing and 

 in full breeding condition, while the other, like it in plumage, had the 

 testes small. 



