The effect of lunar illumination on movement and activity of the red fig-eating bat (Stenoderma rufum)

TitleThe effect of lunar illumination on movement and activity of the red fig-eating bat (Stenoderma rufum)
Publication TypeJournal Article
Year of Publication1997
AuthorsGannon, MR, Willig, MR
Accession NumberLUQ.187
KeywordsStenoderma rufum

Moonlight is an environmental variable which depresses nocturnal activity in animals including insects (Williams & Singh 1951), rodents (Clarke 1983, Kotler 1984), and birds (Nelson 1989, Brigham & Barclay 1992). Moonlight has also been reported to reduce activity in bats by causing them to emerge later, or to restrict their flights and feeding to shadows (Reith 1982, Jones & Rydell 1994). Among the New Worl phyllostomids, Artibeus jamaicensis (Morrison 1975)and Desmodus rotundus (Crespo et al. 1972) significantly reduce activity during periods of high lunar illuminations. This behaviors, termed lunar phobia (Morrison 1978), suggests that flying in the moonlight may significantly increase risk of predation by visually oriented predators. Predation pressure is a probable cause of this behavior because neither resource abundance and distribution, nor social activity in bats, is correlated with lunar illumination (Morrison 1978). Reduction activity during periods of high lunar illumination is assumed to hold true for many other bat species (Erkert 1988). Using radio telemetry, we examined the effects of lunar illumination on the movement patterns of the red fig-eating bat, Stenoderma rufum, on Puerto Rico (Greater Antilles). In general, we evaluated differences in a variety of movement and activity parameters, the extent to which these parameters are affected by sex and age bats, and whether reduced foraging activity occurs during periods of high lunar illumination. Because Puerto Rico lacks most of the visually oriented bat predators commonly found in mainland tropical settings, our prediction was that foraging activity and movement would not vary due to the amount of lunar illumination present.