Sunset as an Orientation Cue in White-Throated Sparrows

Abstract

The importance of sunset as a fall orientation cue in the white-throated sparrow {Zonotrkhia albkollis) was examined under clear skies, cloudy skies, and after sparrows were denied sunset exposure. Sparrows tested during sunset under clear skies exhibited a significant southerly orientation. Those tested under cloudy skies exhibited a more dispersed orientation which was not significant. Sparrows denied sunset exposure but allowed to view stellar cues, exhibited a marked decrease in activity and no directional preference. Results suggest sunset is a primary visual cue functioning in selection of direction prior to nocturnal fall migration.