Seasonal movements and environmental triggers to fall migration of Sage Sparrows

Post-breeding ecology of shrubland passerines prior to onset of migration is unknown relative to dynamics of breeding areas. We radiomarked and monitored 38 Sage Sparrows (Amphispiza belli ssp. nevadensis) at one site in Oregon and two in Nevada from September to mid-November 2007 to track local movements, estimate seasonal range sizes, and characterize weather patterns triggering onset of migration. Median area used by Sage Sparrows monitored between 3 and 18 days during or prior to migration was 14 ha; maximum daily movement was 15 km. Radio-marked Sage Sparrows at each location departed individually, rather than en masse, corresponding with passage of cold front weather systems. Conventional telemetry techniques limited our ability to monitor Sage Sparrows beyond pre-migratory periods and precluded detecting and tracking actual movements during migration. ?? 2011 by the Wilson Ornithological Society.