Animal Fact Sheet
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Pallid Bat
Antrozous pallidus
What does it look
like?
Pallid Bats are a pale buff-colored medium-sized bat. They weigh
less then one ounce, but have a wing span of nearly nine inches.
Their ears and eyes are larger then most insectivorous North American
bats. Like all bats, their hands and arms are modified to form a
wing. The arm and hand bones form the frame of the wing, and a double
layer of skin forms the wing membrane. The wings of bats are living
tissue, unlike the feathers of birds. The wing of a bat or a bird
forms an airfoil like the wing of an airplane. The flapping of a
bat’s or bird’s wing performs the propulsive function
of an airplane’s propeller. Bats are mammals like us. So they
have hair and give birth to young that suck milk from their mother’s
teats.
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| Where
in the world?
Pallid Bats are found in the arid West of North America. They spend
the day-light hours hidden in the crevices of canyon walls or in
the cracks and crevices of old buildings. They are active only at
night. So in their daytime retreats, they sleep. During the winter,
most Pallid Bats hibernate in deep crevices in canyon walls or deep
in caves where the temperatures are cool and constant.
What are some behaviors?
One of the most extraordinary features of insectivorous bats is
their ability to navigate in their environment and to find food
using only echolocation. Echolocation is like sonar. A bat can voice
a high frequency sound, a sound so high in frequency that humans
cannot usually hear it. When the sound hits an object, for example
a wall or a flying gnat, the sound bounces off the object and the
bat hears this echo. From the echo, the bat can determine many characteristics
of the object from which the sound bounced, such as distance, motion
and direction of travel, texture, size and shape. A bat can detect
a single human hair dropping to the ground in total darkness using
only its echolocation. Pallid Bats have bigger eyes and probably
better eye sight than most insectivorous bats.
What about offspring?
Pallid Bats mate in the fall, sperm is stored in the female reproductive
tract until spring when fertilization occurs and gestation begins.
Female Pallid Bats give birth to one, sometimes two, offspring early
each summer within a maternal colony deep in a canyon crevice. This
is usually a warm retreat. The youngster is blind and naked at birth.
It clings to its mother and nurses during the day. At night, while
mother is out feeding, the youngster hangs on the crevice wall waiting
for mother to return. Maternal colonies can include up to 200 females
and young. The young first fly from the roost at about six weeks
of age.
The males do not roost with the females in the
maternal colony roost, but seek their own daytime roosts. These
roosts are usually much cooler then the maternal roosts. The coolness
of the male day-roosts allows the males to conserve energy by going
into torpor each day. |
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What does it eat?
Pallid Bats are insectivorous. That means they eat insects. Most
bat species in North American are also insectivorous, but a few
are also nectarivorous (eat the nectar and pollen from flowers like
the saguaro), frugivorous (fruit-eating), and a few from tropical
America are sanguivorous (blood feeders). All the bats in California
are insectivorous with an occasional record of a nectar feeder.
Pallid Bats are different from other local insectivorous
bats. Most of our bats feed on only flying insects like moths, beetles
and mosquitoes. Pallid Bats specialize on large-bodied, crawling
arthropods like crickets and scorpions. So they are adept at landing
on the ground and quickly taking-off from the ground, unlike most
local bats. A Pallid Bat can eat half of its body-weight in one
night. A mother nursing young can eat her entire body-weigh in crickets
in one night.
Is it threatened
or endangered?
Pallid Bats are common in southern California. There are some bats
in southern California that are of special conservation concern,
such as the Southwestern Yellow Bat and the Spotted Bat. More then
20 species of bats can be found in southern California. In mammals,
only rodents are more diverse. |
