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Earth Dr Reese Halter's Blog

NATURE'S BLUEPRINT

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The mysterious bat – far from blind and rarely given to sucking blood – symbolizes the remarkable diversity of wild animals within the West.

There are at least 16 bat species in the West and they all devour insects, making them remarkable pest managers. Two common fallacies need to be dispelled: first, bats are not blind, even nocturnal bats have good eye sight; second, the superstitious lore of a blood sucking creature is unwarranted and, in most bat species, untrue.

There are over 1,000 kinds of bats worldwide and they live on every continent except Antarctica. Most bats rely on insects as a food source, others on fruit and only a few species attack other animals.

Western bats are not all rabid nor are they the chief vectors of rabies in the West. In fact, British Columbia and Washington state have the least reported cases of rabies of any western state or province.

Bats are the only mammal capable of flying. Their wings consist of a double membrane adjoining a bony structure resembling a human hand.  The extra long fingers and membrane run downward to include a tail. Only the thumbs are free, and the thumb claws are used for climbing and turning around during roosting (or perching). For bats, that  means hanging upside down.

When most animals hang upside down, blood rushes to the head; but not in bats. They have special valves in their veins to keep the blood moving through their bodies when inverted.

How much energy do bats use to fly? Lots. Western bats flap their wings between 10 and 20 beats every second and they reach speeds of between four and 22 miles per hour (seven and 36 km./hr.). In order to achieve these speeds, their heart must pump at about 1,000 beats per minute.

Bats have learned to compensate for high energy needs by lowering their body temperature. They have an internal adjustable thermostat, when inactive body temperatures fall from 113 to 41 degrees F (40 to 5 degrees C). Heart rates drop from 100 to 200 beats per minute while resting and to five beats per minute during hibernation.

To hibernate, bats must have a 40% fat reserve. Its a good thing that bats are excellent hunters. One bat can eat up to 600 mosquitoes in an hour. They also feast upon moths.

To catch insects bats use echolocation, or sonar, to locate their prey. In addition, bat sonar enables navigation with ease in total darkness. High frequencies are emitted from the voice-box and when the waves hit an object the bats’ sensitive ears hear echoes and differentiate between trees, rocks or prey.

All nature’s creates have marvelous adaptations and moths are no exception. They have evolved fine hairs which detect bat sonar. When a bat hunts for a moth it is analogous to high-tech warfare between modern fighter planes. Moths are able to zig-zag and free fall like  sky-divers. When moths free fall, bats somehow calculate the angle of incidence and make a pouch using their tails to form an inverted scoop, often catching their prey. And once caught, they rapidly chew the moth up to seven times per second.

Eight of the 16 bat species in the West are either threatened or endangered. Predators include snakes, hawks, owls, cats, raccoons, skunks, weasels and martens. And unfortunately, human activity – especially insecticides – have had the most detrimental impact on bat populations.

These mysterious flying western mammals are truly incredible and worthy of both praise and conservation.

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Earth Dr Reese Halter is an award-winning broadcaster and distinguished biologist. His latest books are The Insatiable Bark Beetle and The Incomparable Honeybee

Contact Earth Dr Reese Halter

Text © by Dr Reese Halter 2012. All rights reserved.

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