Contrasts in Scheduling of Molt and Migration in Eastern and Western Warbling-Vireos

• DOI: 10.2307/4089119
• Publication Date: 2012-09-14T12:09:57Z
• Authors: Gary Voelker; Sievert Rohwer
• Keywords: Plumage; Flight feather; Territoriality; Spawn (biology)

Using museum specimens, we determined that Eastern (Vireo gilvus) and Western (V. swainsonii) warbling-vireos have contrasting schedules for their prebasic molt relative to fall migration. Adult gilvus replace primaries rapidly (38 days) complete after breeding but while still on the grounds. In contrast, adult swainsonii breed north of Mexico begin body grounds appear continue it during These birds leave United States Canada before initiating remigial molt, our data suggest many them stop in northwestern replacing flight feathers. take longer (55 than do gilvus, presumably because most or all migration has been accomplished prior initiation molt. Hatching-year remain until first (body only) is completed, thus are present long adults left. Both species undergo a prealternate plumage, occasionally innermost secondaries pair rectrices, wintering Our results, along with previous studies migration, highlight importance southwestern nonbreeding biology several passerines western North America.