Why do bats
live in caves?
They do it to avoid danger and
save energy. The largest bat colony,
in Bracken Cave, Texas, is thought to
contain 20 million bats. Some species
use caves for daytime roosting, others
hibernate there for the winter because
caves provide optimal humidity, a stable
low temperature, and few disturbances
from light or noise. Temperature is
important because bats are warm-
blooded but very small. Unlike other
mammals they let their internal
temperature drop when they are resting,
going into a state of decreased activity
to conserve energy. Hibernation is an
even deeper state of inactivity in which
their body temperature drops to that of
the cave.
A special adaptation allows bats to
hang upside down for months without
using any energy. A tendon from their
talons is connected to their upper body,
not to a muscle. So when they hang the
weight of their body holds them in place.
They can then drop straight into flight
when they wake up. SB
PHOTO: STEPHEN ALVAREZ/CATERS NEWSThousands of bats
form dark patches on
the walls of Hubbard’s
Cave, TexasBY OUR EXPERT PANEL
YOUR QUESTI0NS ANSWERED
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Susan is a visiting
psychology
professor at the
University
of Plymouth. Her
books include The
Meme MachineSUSAN
BLACKMORE
Alastair is a
radio astronomer
at the Jodrell
Bank Centre for
Astrophysics at
the University of
ManchesterDR ALASTAIR
GUNN
After studying
physics at Oxford,
Robert became a
science writer. He’s
a visiting reader in
science at Aston
UniversityROBERT
MATTHEWS
Starting out
as a broadcast
engineer, Gareth
now writes and
presents Digital
Planet on the BBC
World ServiceGARETH
MITCHELL
Luis has a BSc in
computing and an
MSc in zoology
from Oxford. His
works include
How Cows Reach
The GroundLUIS
VILLAZON