Hitherto treated as conspecific with S. griseicapillus, but differs in the pace (score 3) and note length (3) of its song, being a trill or rattle rather than a deliberate series of notes#R, and in smaller size and shorter bill (all taxa except aequatorialis; score at least 1) or in its slightly more olive underparts (1) and much paler wings and tail (aequatorialis; 2). On basis of size and gross plumage coloration, races form two major groups, “griseus group” in Central America and N South America, and monotypic “aequatorialis group” on Pacific coast of South America. Geographical variation largely clinal across much of Mexico through Central America to NW South America, birds becoming smaller and paler to S; birds from N of Isthmus of Tehuantepec (S Mexico) named as race harrisoni are indistinguishable from jaliscensis (both generally larger and greyer than birds farther S), although intermediates between harrisoni and sylvioides reported from Puebla; forms synonymized with sylvioides, which also intergrades with gracileus in S Belize, have been described from W Panama S to N Colombia (levis), E Panama (veraguensis) and Colombia (enochrus), where numerous intermediates occur and marked individual variation apparent. Revision of taxonomy and distributional and elevational ranges of lineages in this polytypic species is required, including larger samples of vocalizations and greater series of recent specimens#R. Seven subspecies recognized.
Food and feeding
Status and conservation
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