Journal of Tropical Ecology



Activity patterns and habitat preferences of insectivorous bats in a West African forest–savanna mosaic


Christoph F. J. Meyer a1p1, Christian J. Schwarz a1 and Jakob Fahr a2p1c1
a1 University of Würzburg, Department of Animal Ecology and Tropical Biology, Theodor-Boveri-Institut, Biozentrum, Am Hubland, D-97074 Würzburg, Germany
a2 University of Tübingen, Department of Animal Physiology, Auf der Morgenstelle 28, D-72076 Tübingen, Germany

Article author query
meyer cf   [PubMed][Google Scholar] 
schwarz cj   [PubMed][Google Scholar] 
fahr j   [PubMed][Google Scholar] 

Abstract

We studied activity patterns and habitat use by insectivorous bats in Comoé National Park, Ivory Coast. Bat foraging activity was quantified along five transects representing three different habitat types using acoustic monitoring and captures with mist nets and harp traps. Aerial insect abundance was assessed using a light trap; in addition shrub and tree arthropods were sampled. Bat activity was significantly and positively related to insect availability and ambient temperature, whereas increased visibility of the moon had a negative influence on flight activity. Together, these factors best explained both total bat activity and activity of bats hunting in open space and edge habitats. The interaction between temperature and light intensity was the best predictor of activity by species foraging in obstacle-rich forest habitats, however, the regression model had a low predictive value. Overall, a large proportion (c. 50%) of the variation in bat activity appeared to be a consequence of transect- and/or habitat-specific influences. We found a significant non-linear relationship between the activity of QCF (quasi-constant frequency) and FM–QCF (frequency modulated – quasi-constant frequency) bats and the phase of the moon, with lowest levels of activity occurring near full moon. We interpret this lunar-phobic behaviour as a reflection of a higher predation risk during moonlit periods. For FM (steep frequency modulated) and CF (constant frequency) bats, no significant correlation was found, although there was a trend suggesting that these bats at least were not negatively affected by bright moonlight. Foraging activity of bats was positively correlated with the abundance of atympanate moths; however, no such correlation was found for tympanate moths.

(Accepted June 17 2003)


Key Words: abiotic factors; activity patterns; Chiroptera; Côte d'Ivoire; guilds; habitat heterogeneity; habitat use; insect abundance; Ivory Coast; moonlight; predation pressure.

Correspondence:
c1 Corresponding author. Email: jakob.fahr@biologie.uni-ulm.de
p1 Current address: University of Ulm, Department of Experimental Ecology, Albert-Einstein-Allee 11, D-89069 Ulm, Germany