Use of leaves as roosts by the Gervais' fruit-eating bat, Artibeus cinereus (Phyllostomidae: Stenodermatinae) and proposed modifiability index

Abstract

The Order Chiroptera includes at least 22 species of leaf-modifying bats (Kunz and Lumsden, 2003; Munoz-Romo and Herrera, 2003; Tello and Velazco, 2003). Tent roosts tend to be transitory due to their unstable nature, and tent-making bats frequently move between roosts and presumably continuously construct them. There are 10 patterns of leaf modification currently recognized, eight of which result in tents (Kunz and Lumsden, 2003; Munoz-Romo and Herrera, 2003; Rodriguez-Herrera et al., 2007). Although leaves can be considered as unlimited and ubiquitous resources, only a small proportion of leaves are effectively modified and used as roosts by bats (Kunz, 1982; Kunz and McCracken, 1996; Kunz and Lumsden, 2003). The current hypothesis is that bats select only the most suitable leaves to construct tents. Several factors appear to influence leaf selection before tent construction is initiated (Timm, 1987; Kunz and McCracken, 1996; Stoner, 2000). Age of leaf and height above the ground seem to be the most important (Timm and Mortimer, 1976; Choe and Timm, 1985; Brooke, 1987, 1990; Timm, 1987; Timm and Lewis, 1991; Stoner, 2000; Kunz and Lumsden, 2003; Chaverri and Kunz, 2006). In December 2001, we observed groups of the Gervais’ fruit-eating bat, Artibeus cinereus, roosting in a small banana (Musa sp.) plantation. Our study was designed to characterize the use of leaves by A. cinereus in this plantation, and to explore factors that may influence leaf selection in this tent-roosting species. The Gervais’ fruit-eating bat is a small (10–13 g) neotropical tent-making bat, known to modify leaves that result in five architectural styles (i.e., palmate umbrella, apical, bifid, pyramid, and boat) in species of plants represented by the families Araceae, Heliconiaceae, Pal mae and Musaceae (Timm, 1987; Kunz and Lums den, 2003). For our study, we investigated the use of Musa sp. leaves as roosts. Owing the abundance of these leaves at our study site we developed an index for leaves that we propose as an indicator of leaf modifiability.