Credit: MICHAEL & PATRICIA FOGDEN/CORBIS

Bats are usually thought of as roosting in caves or buildings. But there are several do-it-yourself tropical species that create tents out of large leaves. They do this by biting the leaf in such a way that the sides collapse downwards and create a sheltered area — as shown here (from within, complete with bat occupants).

These tents can stay healthy for long periods, even though much of the leaf's water supply has been cut off. How? Carol A. Peterson, Brock Fenton and colleagues have tackled the question by looking at the leaves of three plant species used by bats in Costa Rica (Biol. J. Linn. Soc. 72, 179–191; 2001).

The group examined the water-conduction system in the leaves, and the damage caused to it by bats, and also performed tests with a tracer dye to follow water flow in damaged and undamaged tissue. The vein system in the leaves is complex, consisting of an apparent hierarchy of some five conducting elements. But it seems that water conduction by the smallest elements is enough to sustain the leaf, even when more major veins are severed. The authors point out that the advantage for the leaf is that it can survive damage from, say, wind or heavy rain; for the bats, it means that they are not forever making new tents.