Ed Yong writes in National Geographic about a Nepenthes (Nepenthes hemsleyana) that provides a species of bat (Hardwicke’s woolly bat, Kerivoula hardwickii) with shelter in return for food:

With Sonar-Reflecting Leaves, Plant Lures Bats to Poo in it

Imagine a bat flying through the jungle of Borneo. It calls out to find a place to spend the night. And a plant calls back.

The plant in question is Nepenthes hemsleyana—a flesh-eating plant that’s terrible at eating flesh. It’s a pitcher plant and like all its kin, its leaves are shaped like upright vases. They’re meant to be traps. Insects should investigate them, tumble off the slippery rim, and drown in the pool of liquid within the pitcher. The pitcher then releases digestive enzymes to break down the corpses and absorb their nitrogen—a resource that’s in short supply in the swampy soils where these plants grow.

But N.hemsleyana has very big pitchers that are oddly short of fluid and that don’t release any obvious insect attractants. And when Ulmar Grafe from the University of Brunei Darussalam looked inside them, he saw seven times fewer insects than in other pitchers.

Instead, he found small bats.

Read the scientific paper here:
Bats Are Acoustically Attracted to Mutualistic Carnivorous Plants.
Current Biology. Schöner, Schöner, Simon, Grafe, Puechmaille, Ji & Kerth. 2015.

Tiny bat makes home in a carnivorous plant
by Mićo Tatalović
New Scientist, 24 February 2015

BATS roost in big groups in caves. Wrong! If you’re a Hardwicke’s woolly bat, you prefer to sleep in a more luxurious – and private – place.

Kerivoula hardwickii roosts inside tropical pitcher plants. These carnivorous plants usually attract insects, but Nepenthes hemsleyana lacks the scents that others have, so few bugs are lured in. Instead, it benefits from the faeces of this tiny bat, which provides more than a third of its nitrogen and may be crucial to the plant’s survival.

“This is the only bat species that has ever been found roosting in pitchers,” says Caroline Regina Schöner, whose team discovered the bats in 2009. “These bats managed to find a niche that no one else is occupying.”

Video of bat entering a pitcher.

More pictures can be found on Google Images.

An article on Kerivoula sp. on the Ecology Asia site.