Many Central American hummingbirds can be aged and sexed by molt patterns and bill corrugations

Abstract

. We document molt extent; age-specific molt patterns, plumages, and percent of the bill with corrugations; the presence or absence of delayed plumage maturation and bill color changes in males of some species; and molt timing in the 19 resident hummingbird species of Belize. Molt strategies and rates of bill smoothing were similar to North American species, with all species showing limited to partial preformative molts, replacing only body feathers and some wing coverts and retaining all remiges and rectrices. Extent of bill corrugations reduced to ≤10% of bill length in all species by the time definitive cycle basic plumage is achieved. Males in sexually dichromatic species showed delayed maturation in plumage characteristics and/or bill coloration, and in two dichromatic species some older females showed male-like plumage. Nine species representing multiple clades showed advanced timing to the second prebasic molt, indicating that this trait may be a proximal response to individuals not breeding during the first molt cycle. Species with advanced second prebasic molts replaced fewer wing coverts during the preformative molt than species with later molt timing.