Monday, May 17, 2010

Apple #457: Bats

I was out in the woods the other evening, I saw a fair number of bats flying around.  This reminded me, I like bats.

Bats flying at dusk. These are actually Mexican Free-Tailed bats, one group of which lives in an enormous colony of several million near San Antonio, Texas.
(Photo from Nature's Crusaders)

A bat got in my house once.  I was in bed with the lights off, and I heard it whooshing around above my head.  Since I couldn't see what it was, at first, I was kind of terrified.  But once I got the light on and saw what it was, and when I saw that it was following a sort of pattern around the room near the ceiling, I got over being afraid of it and tackled the problem of how to get it outside.

I went downstairs to get a container large enough for it, and when I came back upstairs, it had flown into the other bedroom.  I shut myself in there with the bat so he couldn't fly into another room.  He flew around and around and then paused on the molding at the top of one of the windows.  He had bright eyes, a small, quick face, and his wings looked leathery but soft.

I talked to him.  I said, "You're not going to be happy in here because there's no food for you to eat."  I noticed that any time I said a word with an "s" sound in it, his ears moved.  So I said a lot of other things to the bat, trying to use a lot of "s" words.  During our conversation, he left the top of the window and flew around the room quite a few times, but he flew around less often and stayed on the window longer.  Finally as he was pausing, listening to my "s" words, I was able to get close enough to him, said I was sorry, and clapped him in the huge container that had once held many gallons of frozen yogurt.

I quick opened the window, held the container outside the window, lifted off the lid, and he flew out right away.  He seemed to be unhurt.  As soon as he was gone, I missed him.  It was nice having a guest.

A bat in the house may read your good books?
(Photo from Get Rid of Bats)

I just looked up what you're supposed to do if you have a bat flying around in your house.  Basically, I did what they recommend.  But because there is a faint possibility that a bat could carry rabies, I should have gotten a rabies vaccination.

If you have one bat in your house, open a window and chances are the bat will fly out on its own.  If that doesn't happen, put on thick gloves, find something like a net or a large container, and capture it long enough to release it outside.  Then you should stop by the hospital or the doctor's office and get a precautionary rabies vaccination.

If you have lots of bats living in your house, it seems counter-intuitive, but build a bat-friendly house for them in your yard.  Then when it's dark, wait for them to fly out to find food and close up any holes where they could get in.  When they come back, if they can't get into your house, they'll move into the bat house.  More details about that process are available here.

Bat houses work best when they're made of cedar and mounted under eaves but with exposure to the sun to keep them warm. This bat house by Looker Inc., is one of many types that are made to the Organization for Bat Conservation specifications. This means it will have a better chance of attracting bats already in your house, and of keeping them there so they will eat the bugs you don't want in your yard or on your plants.

  • There are over 1,100 species of bats.
  • Bats represent 20% of all species of mammals.
  • They are the only mammals capable of true flight.
  • Bats are very long-lived for their size.  Most live to be around 15 or 20 years old.

What I find interesting about bat anatomy is that it is literally the arms and the fingers that support the wings.
(Photo from Bat Conservation International)

  • The fact that bats use their arms and hands to fly is essentially the reason they sleep upside down.  They're resting their arms.  Their feet aren't made for walking, but like birds' feet, their at-rest position is a grasping position.  So when their feet are relaxed, they're curled around the branch and the bat can fall asleep, nicely relaxed.
  • They don't have the problem with blood rushing to their head like humans do.  Because of their small size, blood distribution isn't an issue, so it doesn't matter to their circulatory system whether they're right-side-up or not.
  • Bats are not blind.  Really.  In fact, most species of bats have excellent vision.
  • Like dolphins, they "sound" out their territory by echolocation.  They make high-pitched tweets and are able to analyze the echoes that bounce back.  Not only do their know where their friends and relatives are, they also know where obstacles are so they can avoid them.  
  • Their echolocation systems are so good, they can detect obstacles as fine as a human hair.
  • Which therefore means they will not get caught in your hair.
  • One handy way to categorize the species of bats is by the food they eat.

Species of bats divided up according to the foods they eat.
(Pie chart from Bat Conservation International)

  • Nearly 2/3 of bat species eat bugs.  And they eat a lot of bugs.  One small brown bat can eat about 1,000 bugs the size of mosquitoes in only one hour.
  • A female bug-eating bat who is either pregnant or lactating will eat her entire body weight in bugs each night.
  • Nearly all the species of bats who live in North America are bug-eaters. 

This is the Eastern Red Bat. It's the most common tree-dwelling bat in North America.  It lives anywhere from the northernmost tip of Maine down to central Florida, and west until about the Rocky Mountains.  They come out to eat early in the evening, often at the edge of forests or even around streetlights where moths are plentiful. While sleeping, they curl their tails around them and are often mistaken for dangling pine cones or dead leaves.
(Photo from Bat Conservation International)

  • Many bug-eating bats will migrate to nearby caves or mines to hibernate for the winter, but some travel from as far north as Canada to as far south as Mexico.
  • As with many migrating animals, researchers aren't sure how bats find their way back to the same hibernation and summer homes each year.
  • Most mammals mate in the spring, but not these bats.  Most of these species mate in the fall.  Then they all go hibernate for the winter.  When the female wakes up in the spring, she ovulates, and the egg is fertilized by the sperm that has lain dormant inside her all winter.
  • Once she's pregnant, she'll move from her winter roost to another roost that's warmer.  Lots of other female bats will find the same roosting spot, and they'll form a nursing colony.  The babies are born about 2 and a half months later.

You'd think this bat would be called Big-Eared Bat, but actually this is the Spotted Bat.  Its ears are pink and so are its wings. I'm not sure where the spots are, actually.  It's very rare and it eats only moths. Its territory ranges from southern British Columbia in sort of a stripe all the way down to the middle of Mexico.
(Photo from Bat Conservation International)

  • The other 1/3 of bats eat plant nectar or fruit.  Most fruit-eating bats live in tropical climates.

This is the Straw-Colored Fruit Bat, which lives in Africa.  As shown in the photo, they can use their "fingers" for help in climbing along tree branches.  These bats are fairly large, they don't mind flying around in the daytime, they like to eat the fruit of palm trees, and they're very gregarious.  Sometimes they form colonies as large as 1,000,000 bats.
(Photo from the Organization for Bat Conservation)

  • Fruit-eating bats also act as pollinators of the plants whose fruit they eat.  The fruit-eaters are also very good at, um, fertilizing and distributing the seeds of their favorite plants.
  • Some of the plants that bats pollinate include bananas, avocados, peaches, mangoes, figs, cashews, and agave.
  • Flying foxes are the largest species of bat.  They live in Indonesia and Australia.  Their wingspans reach nearly six feet.

This is the Egyptian Fruit Bat. They live, obviously, in Egypt, but also in Pakistan, Turkey, and around the Arabian Peninsula.  Males will roost in the nesting colony with the females.
(Photo from the Organization for Bat Conservation)

  • A tiny fraction of other bat species eat small animals like fish, mice, or frogs.

The Fringe-Lipped Bat is one of the few species that eat frogs, or anything other than bugs or fruit.  This bat lives in Panama.
(Photo by Alexander T. Baugh from the University of Texas at Austin)

  • Only 3 species of bats are vampire bats, and all 3 species live in Latin America.  

A vampire bat. Boy am I shaking in my boots at the sight of that tiny little thing.
(Photo from Life123)

  • They do feed on blood, but only the blood of birds, cattle, horses, and pigs.  They typically go up to livestock while they're sleeping, cut open the skin with their teeth, and lap up the blood.
  • They don't suck blood but rather they lap it with their tongues.  They have never attacked a human.
  • The saliva of vampire bats contains two handy enzymes. 
  • The first numbs the skin around the bite and keeps the animal from waking up.
  • The second enzyme dissolves blood clots. This keeps the blood which is their food flowing.  But researchers have managed to collect the enzyme and use it to treat people who have had strokes.
  • Some vampire bats will adopt young orphan bats, which is very rare for any wild animal. 

A nectar-eating bat. I don't know any more about it than that. But it's a cool photo.
(Photo from aaaaaahhhhshark)

Okay, so maybe most bats won't win a beauty pageant.  But is that any reason to make up all sorts of lies about them?  I think not.  And would you rather have millions more mosquitoes?

Oh, and how could I forget:  "You wouldn't hit a bat with glasses on, would you?"  Still makes me laugh.

Bat Conservation International, All About Bats
Defenders of Wildlife, Bats
Contra Costa County Office of Education, Bats! Why should you care?
The Wild Ones Animal Index, Vampire Bat
Life123, What Do Vampire Bats Eat 
CoolQuiz! Why Do Bats Hang Upside Down?
DOE Newton Ask A Scientist, Bats Upside Down

1 comment:

  1. The nectar eating bats in southern Arizona are the primary pollinators of the Saguaro cactus, whose blooms are open widest at night.


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