Tropical rainforests are
home to the greatest diversity of bats on the planet.One might think
housing would be an issue, after all, caves are often few and far
between. Not so. Tropical bats have come up with some
innovative ways to open the rainforest real estate market.
Many species of bat will
take advantage of "pre-fab" homes - the bats simply move into a
hollow tree, rock crevice, fallen log, even the over-hang of a
house. One group of bats, though, takes roosting to another
level and actually constructs its own home. These are the
tent-making bats.
Tent-making bats fashion
their homes by biting and chewing the veins and midribs of leaves
until they droop into a cozy tent. The underside of the
leaf provides shelter from both rain and sun, and even acts as an
advanced warning system against potential predators. It would
be near impossible for any animal to approach the bats without
shaking the leaf first. Even the slightest unsettling movement
would trigger the bats to fly out to safety.
Tents
are made from several species of plant, including heliconias,
palms, bananas, philodendrons and others. Thomas' Fruit
Eating Bat, Dermanura watsoni, was documented using 19
different species of plants for tents in Corcovado National
Park. That is more species of plant than any other bat is
known to use.
Depending on the
species of Tent-making Bat, they may roost alone or, with
most species, in small groups. In Drake Bay, Gian
and I have found groups of twenty roosting in tents in our
garden. Amazingly, researchers have documented up to 60
bats from a single tent.
Fruit makes up the greatest
part of a tent-making bats diet. They will occasional eat
nectar, pollen, flower parts, and insects as well.
Gian
and I often encounter tent-making bats on the Night Tour. The
bats we normally see are taking a break form their nightly
rounds, or are feeding on a plucked fruit they have brought back
to the roost. Because they spend most of the night foraging, the
best time to observe tent-making bats is during the day.
The
tent-making bats belong to the subfamily Stenodermatinae,
otherwise known as Tailless or Neotropical Fruit Bats. In
Costa Rica, at least 15 species of Neotropical Fruit Bats
engineer their own roosting sites by shaping leaves.
Accurately distinguishing between the different species of
tent-making bats can be difficult and may require capturing the
bat and looking at subtle differences in size, color, hairiness,
as well as their dentition.
Below is a video of Thomas'
Fruit-eating Bat, Dermanura watsoni, feeding during the
Night Tour
References:
Kricher, J.
1989 A Neotropical Companion Princeton
University Press
LaVal, R. & Rodriguez, B. 2002 Murcielagos de Costa Rica/Bats
Editorial INBio
Wainwright, M. 2002 The Natural History of Costa
Rican Mammals Zona Tropical
Wilson, D. 1997 Bats in Question Smithsonian
Institution Press
Alien Earthlings 
The
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