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 Dark Side
