Behavioural strategies associated with using an ephemeral roosting resource in Spix's disc-winged bat

Abstract

The limited availability of refuges may represent an important factor promoting the evolution of sociality, particularly in bats. Spix's disc-winged bats ( Thyroptera tricolor ) show highly specialized morphological adaptations that enable individuals to roost inside furled musoid leaves. This roosting ecology presents major challenges, as leaves rapidly unfurl, forcing bats to locate new roosts on a daily basis. Despite the reliance of T. tricolor on such ephemeral roosting resources, bats form stable group associations. This social stability has been attributed to the potential benefits that group members gain from searching for new roosts together versus alone. The purpose of our study was to characterize the behavioural patterns associated with assessing roosts and any accompanying communication strategies of Spix's disc-winged bat. We determined that bats regularly monitor furled leaves within their roosting range, during which they emit a number of distinct social calls. Roost assessment involved close inspection of leaf dimensions and surroundings, and was mostly performed by single individuals. Thyroptera tricolor 's call repertoire during flight indicates that group contact involves a combination of acoustic signals. Our approach in a natural setting provides valuable insight into the role of shelter stability in the evolution of the T. tricolor social system. • Thyroptera tricolor form stable group associations despite the need to constantly switch roosts. • We investigated the behaviour involved in the selection of day roosts. • Bats regularly monitor furled leaves within their roosting range during the night. • We document the presence of multiple contact calls emitted by bats near potential roosts. • Contact calls may enable bats to advertise suitable roost locations.