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The
only flying mammal
Picture:
Bats taking
to the air in their search for food.
Picture
courtesy of the Organization for Bat Conservation.
Bats
are not birds, even though they fly. Bats are mammals;
they feed their young milk, have fur, breathe through
lungs, and are warm-blooded. Bats are the only mammals
that can fly. Unlike birds, their wings are not made from
feathers but from skin stretched over their fingers. Because
of this, scientists group bats in the order of Chiroptera,
a name of Greek origin meaning "hand-wing."
The image below from the University of California Museum
of Paleontology shows the fingers that form this hand-wing.
Picture:
skeleton of a fruit bat. The
wings of the bat are formed by skin stretched out over
their fingers.
Move over the image to count the fingers. Picture
courtesy of University
of California Museum of Paleontology
website
More
information about this image
.
More
than 900 bat species
There
are more than 900 species of bats and because there are
only about 4000 or so mammals, bats form almost one quarter
of the total number of mammal species. The Chiroptera
order to which all bats belong is divided into two suborders:
the Megachiroptera and the Microchiroptera.
Picture:
The straw-colored fruit bat, a Megachiropterans. The
straw-colored fruit bat is found in Africa and is the
most widely distributed of the African fruit bats.
Picture courtesy of the Organization for Bat Conservation.More
information about this bat.
Megachiropterans
include the so-called fruitbats and flying foxes of the
tropical forests of India, Africa, Asia, and Australia.
Most of them feed on fruit, although some also like fl
owers
and flower nectar. These megabats navigate largely by
sight and have large forward-facing eyes, as shown in
the picture.
Picture:
The silver-haired bat, a Microchiropterans and watershed
inhabitant.
Silver-haired
bats range from Alaska across southern Canada south through
all the states except Florida. Picture courtesy of
the Organization for Bat Conservation.More
information about this bat.
Microchiropterans
or microbats are more ecologically diverse and live all
through the United States and the watershed. They have
smaller eyes and most of them feed on insects, although
some microbats also eat fruit, flowers, pollen, or nectar.
These insectivorous bats help control insect populations.
Some
of the bat species that occur all through the watershed
are the big brown bat, the silver-haired bat, the red
bat, the hoary bat, the little brown bat, and the eastern
pipistrelle. For a list of all the bat species in the
Chesapeake Bay watershed and other U.S. states, visit
Bat
Conservation International, Inc.
and select Bat Species from their Discovery menu.
Picture:
a newborn big brown bat. Young
bats are usually born naked and helpless with small and
undeveloped wings. However, they grow rapidly and in three
or four weeks the bats can fly and forage on their own.
This tiny bat will
grow to be about four to five inches in length.
Picture courtesy of Robin Russell.
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Finding
insects in the dark
Bats
are nocturnal; they only come out at night to eat. During
the day they rest in tree holes, caves, and dark places
in houses. How do they find their food in the dark_ All
microbats and a few fruit bats have a very clever way
to do this: The bats send out high-frequency sounds and
then listen if these sounds bounce off any objects that
are in their vicinity. By analyzing the returning echo,
a bat can tell the location, speed, and distance of nearby
objects and determine if the object is food or an obstacle
that needs to be avoided. To use this process called echolocation,
microbats often have large, sensitive ears.
To see an animation of echolocation and to hear the echolocation
clicks of several bats, visit the Oakland museum of California:
California
Underground Bat Echolocation station.
Bat
(bad) myths
Some
people think that bats are blind (i.e., as blind as a
bat), that bats may get caught in your hair, or that they
are dirty animals. Well, none of this is true, so there
is no need to fear our flying friends. Bats are very clean;
they clean and groom themselves just like cats. And think
about it: If a bat manages to get up to a 1,000 insects
per hour, would they be such poor navigators that they
get caught in your hair_
If
you hadn't realized it by now: Bats are wonderful and
very useful creatures. While fruit and nectar-eating bats
are important for pollination of crops (e.g., bananas,
avocados, vanilla, and peaches), insect-eating bats are
keeping insect populations under control. So the next
time you are outdoors on a warm evening, look for your
friend the bat overhead, keeping the bugs at bay.
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References
and further reading
:
All links in this section will take you to sites outside
Watershed Radio.
See
real bats
-
To see real bats, try a dark attic or visit the Smithsonian
National Zoo BatCam.
The bat cave at the zoo is home to more than 400 big
fruit bats and short-tailed bats.
- In
addition to the BatCam, you may also learn more about
bats (and other animals) by taking the Audio
Wand Tour of the National Zoo
in Washington D.C. No need to go to D.C., just visit
the tour online. Stop 25 and stop 26 are at the bat
caves. You can listen to Dr. John Seidensticker, curator
of mammals at the National Zoo.
- Infrared
bat images: Visit the Discovery
High-Tech Trackers pages about bats
to see infrared images of flying bats. Infrared cameras
capture images of objects based on the heat they emit
in contrast to their surroundings.
Echolocation
clicks and animation
Bat
organizations and other informational sites
