Carnivorous pitcher plants provide homes for bats

From another interesting piece at Ed Yong's Not Exactly Rocket Science column at Discover:

The world’s worst [?] flesh-eating plant lives in the jungles of Borneo. It’s called elongata and it’s one of several strains of Raffles’ pitcher plant. Like its relatives, it has distinctive pitcher-shaped leaves that can lure insects into a watery grave. But unlike other strains, elongata is strangely incompetent at catching insects. Instead, it lures bats into its pitchers, and lives off their poo...

Elongata looks much like other pitcher plants, except for its giant traps. They’re around four times larger than those of its relatives, they don’t contain much fluid, and they don’t emit any noticeable smell. At such a size, you’d expect the pitchers to be swimming in insects. But when Ulmar Grafe from the University of Brunei Darussalam looked inside the giant pitchers, he found six to seven times fewer insects than in other pitchers. Instead, he found small bats...

In the pitchers, the bats get shelter from predators and the elements. But what does the plant get in return for providing a living bat-cave? In a word: faeces. The bats defecate into the pitchers, providing the plant with at least a third of its nitrogen, packaged in neat dollops.