Tents and harems: apparent defence of foliage roosts by tent-making bats

ABSTRACTPalmate umbrella tents used by tent-making bats in Trinidad, West Indies, were observed in three species of Neotropical palms, Sabal mauritiiformis, Coccothrinax barbadensis and Mauritia flexuosa. Tents were most common in palm leaves that have supporting petioles angled at 50–70° above the horizontal. The shape and volume of tents is influenced mostly by leaf morphology (leaf width and leaflet length) and age of the tent. Tent-crowns varied from being heart-shaped in S. mauritiiformis, oval or round in C. barbadensis and spade-shaped in M. flexuosa. Leaves in which tents were constructed were most often beneath overhanging vegetation, and were generally free of vegetation below, allowing bats to enter and depart from tents without being impeded by the clutter of adjacent vegetation.Singles and small apparent harem groups of two bat species, Artibeus jamaicensis and Uroderma bilobatum, were captured and observed in tents made from the leaves of S. mauritiiformis and C. barbadensis. No bats were observed in tents constructed in leaves of M. flexuosa. The apparent harem social organization in these and other tent-making bat species suggests that leaves modified into tents may provide critical and defendable resources that promote the evolution of polygyny. This hypothesis is based on the observed patchy distribution of suitable palm trees, the inappropriateness of many palm leaves as potential tents and the resultant architecture provided by palmate umbrella tents. We suggest that tent-making is an adult male behaviour.