The Influence of Moonlight on the Behavior of Goatsuckers (Caprimulgidae)

Abstract

Whip-poor-wills (Caprimulgus vociferus) showed significantly higher levels of locomotory, vocal, and nest activity during twilight and bright moonlight than under moonless conditions. Field observations and nest record card data indicated that Caprimulgus species usually synchronize their reproductive cycle with the lunar cycle. Hatching tends to occur during young waxing moons, presumably so that moonlight-enhanced foraging will be at a maximum while the dependent nestlings are an energy burden on the parents. Observations of foraging Whip-poor-wills suggest they are primarily visually oriented, unlike the bats (Chiroptera).