National Bat Appreciation Day occurs annually on April 17th.  April is the best time of the year to observe bats, as they are now beginning to emerge from hibernation. National Bat Appreciation Day is also an excellent time to learn about the role bats play in nature. Of all the creatures associated with the night, perhaps the most misaligned and misunderstood is the Bat.

Fictional characterizations in modern culture, in movies and on TV, have given the bat an evil and sinister reputation, but such could not be further from the truth. In Tonga and ancient Babylonia bats were considered physical manifestations of the Souls of the Dead. In China and Poland they were symbols of Happiness and Long life, and to the ancient Mayans they symbolized Transformation and Rebirth. In ancient Greece and Rome, it was thought that sleep could be prevented either by placing the engraved figure of a bat under the pillow, or by tying the head of a bat in a black bag and keeping it near to the left arm. On the Ivory Coast, even today, many think that bats are the spirits of the dead, and in Madagascar, they are assumed to be the souls of criminals, sorcerers and the unburied dead. In medieval Europe, bats were commonly thought to be witches’ familiars.

Bat Echolocation(sonar)

One important reason to celebrate bats is that they are considered to be an “insectivorous” creature because they rid our world of many annoying insects.  In one hour, a bat can eat up to 1,000 mosquitoes.Bats are not blind; in fact they can see almost as well as humans. But to fly around and hunt for insects in the dark, they use a remarkable high frequency system called echolocation.

Echolocation works in a similar way to sonar. Bats make calls as they fly and listen to the returning echoes to build up a sonic map of their surroundings. The bat can tell how far away something is by how long it takes the sounds to return to them.

These calls are usually pitched at a frequency too high for adult humans to hear naturally. Human hearing ranges from approximately 20Hz (cycles per second) to 15 to 20 kHz (1000Hz) depending on age. In comparison, some bats can hear sounds up to 110 kHz in frequency. By emitting a series of often quite loud ultrasounds that either sweep from a high to low frequency or vary around a frequency, bats can distinguish objects and their insect prey and therefore avoid the object or catch the insect.

Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This means that we can identify many bats simply by listening to their calls with bat detectors.

Fun Bat Facts:

  • Bats can see in the dark and use their extreme sense of hearing.
    Some species of bats can live up to 40 years.
  • Bats are the only mammal naturally capable of true and sustained flight.
  • There are over 1,200 known species of bats.
  • The United States is home to an estimated 48 species of bats.
  • Nearly 70% of bats are insectivores.
  • One of the largest bats is the Giant Golden-Crowned Flying Fox bat weighing up to 4 lbs with a wingspan of up to 5 feet, 7 inches.
  • Bats are clean animals, grooming themselves almost constantly.
  • North America’s largest urban bat colony is found on the Congress Avenue Bridge in Austin, Texas. It is home to an estimated 1,500,000 Mexican Free-Tailed bats. This colony of bats eats approximately 10,000 to 30,000 lbs of insects each night.  It is estimated 100,000 tourists visit the bridge annually to watch the bats leave the roost at twilight.
  • One colony of 150 Big Brown bats can protect farmers from up to 33 million or more rootworms each summer.
  • Almost 40% of American bat species are in severe decline, with some already listed as endangered or threatened.
  • Three U.S. states have an official state bat. Texas and Oklahoma have named the Mexican Free-Tailed bat their state animal.
  • If you are in film noire with the addition of bats, here is a list of movies that you can cuddle up with on the couch one evening. But beware, if you feel a slight brush up against your hair as you are sitting there, it maybe winged mammal friend pursuing a mosquito or two.