Bats can be a little scary-looking, but the diverse flying mammals are broadly beneficial to the ecosystems where they — and we — live. Below are 13 facts about these underappreciated creatures.
1. Bats account for about 20% of all mammal species.
With more than 1,200 species included in the order Chiroptera, bats represent one of the largest orders of mammals. They are surpassed only by the order Rodentia, which boasts a whopping 2,277 species — 40% of all mammalian species.
Chiroptera is separated into two suborders: megabats and microbats. Megabats, commonly known as fruit bats or flying foxes, have excellent vision and feast on fruit and nectar. Microbats, like the painted bat of Southest Asia (pictured), are characterized by their use of echolocation and an appetite for insects or blood.
2. Bats are found across the planet.
As with birds, flight has allowed bats to travel and settle in all corners of the Earth, with the exception of the Arctic and Antarctic. Bats generally roost in caves, crevices, foliage and man-made structures like attics or under bridges.
At least 45 species of bats are present in the United States alone, with the most common species being the little brown bat, the big brown bat and the Mexican free-tailed bat.
3. Microbats use echolocation to hunt prey.
Although microbats are not blind, their true perceptive strength lies in their ability to use echolocation, also known as biosonar.
Bats aren't the only animals that can use biosonar. Shrews, dolphins and some cave-dwelling birds also use echolocation to navigate their surroundings and hunt for prey.
As bats forage for food, they emit a continuous stream of high-pitched sounds audible only to other bats. When the sound waves collide with a nearby insect or object, the interrupted waves echo back, generating an acute sonic representation of the bat's surroundings. This ability is so sensitive that it can detect objects as thin as a single human hair.
Some species are equipped with specific characteristics that allow for more fine-tuned biosonar readings. For example, the Mediterranean horseshoe bat (pictured) is named for its peculiar, horseshoe-shaped nose leaf — a fleshy, complex structure surrounding the nostrils that helps focus sound waves. Likewise, long-eared bats possess prominent ears with geometric inner ridges that sharpen echolocation signals and allow for passive listening of sound produced by prey, such as the fluttering of moth wings.
Another type of bat, the common big-eared bat, makes use of a natural tool to catch difficult prey — specifically by angling sound waves off a leaf to fine tune the location of motionless prey. As Smithsonian aptly describes it, the bats use leaves as "acoustic mirrors," a habit discovered by Inga Geipel, a scientist at the Smithsonian Tropical Research Institute (STRI) in Panama, and a team of scientists there. Besides just being interesting, this knowledge also rules out a common belief: that the one way to defy echolocation is to remain motionless and silent. For the dragonflies in this experiment, that turned out not to be the case.
4. Bats 'waggle' their heads to hear better.
You know how a dog cocks its head as if to better understand what a human is saying? Well, bats do the same thing, only they do it while flying. As you can see in the video above, the motion is similar to what dogs, cats and even humans do, but bats do it for a different reason: to fine tune the location of prey as they're echolocating.
The Christian Science Monitor — which artfully compares the motion to a tiny flying puppy — explains the research of Melville Wohlgemuth of Johns Hopkins University. Wohlgemuth, a neuroscientist whose specialty is echolocation, sums it up relatively simply. The bat has to sort out the clutter, and turning its head allows it to do that.
5. Bat colonies save us billions in agricultural pest control.
There's no need to use harmful pesticides when you have a robust colony of bats nearby. Some individuals bats can eat more than 600 flying insects per hour — making bats a perfect choice for organic pest control. Without them, we humans might as well bow down to our insect overlords.
The agricultural value of these flying mammals cannot be overstated, but scientists predict this could change within the next decade as North American bat populations face an uncertain future as a result of emerging threats — from habitat loss to disease. (More on that below.)
6. Female bats can control when they get pregnant and give birth.
Bats can delay the development of a fetus so a birth can coincide with high production of fruit or insects in the environment. (Photo: Mnolf [CC BY-SA 3.0]/Wikimedia Commons)
To ensure external conditions are optimal for a newborn bat, mother bats are equipped with a variety of biological tactics that allow them to put off fertilization, implantation or development of the fetus.
In some species, mating will occur in the fall, but females will store sperm in their reproductive tract before finally fertilizing their eggs when spring arrives. In other species, the egg is fertilized immediately after mating, but instead of implanting to the wall of the uterus, it floats around until favorable conditions arrive. Yet another adaptation exhibited in some bats is delayed fetus development, in which fertilization and implantation occurs as usual, but the fetus remains in a dormant state for a long period of time.
These tactics, which contribute to the slow birth rate of bats, are timed to coincide with high production of fruit or insects in the environment.
7. Yes, some bats live off blood.
Contrary to popular belief, vampire bats don't actually suck blood. Instead, they use their razor-sharp teeth to make a small incision in the skin of a sleeping animal and then consume the blood as it runs from the wound.
Unlike the monsters of popular vampire lore, bats only require about two tablespoons of blood a day, so the victim's loss of blood is negligible and seldom causes harm. Additionally, bat saliva has a similar anesthetic quality to that of a mosquito, which helps prevent the victim from even feeling the cut.
8. Megabats prefer a vegetarian lifestyle.
About 70% of all bats are insectivores (with the exception of a small percentage that drink blood or eat fish), but megabats are mostly frugivores that feast on fruit, pollen and nectar.
Also known as flying foxes, these fruit bats play an important role in the pollination of flowers and the dispersal of fruit seeds. Their dietary habits are beneficial for rainforests, which contain a large variety of flora available for consumption.
Unfortunately, due to deforestation and the inherently fragile state of rainforest ecosystems, nectar-feeding bats are especially prone to extinction.
9. Bats hang upside-down to conserve energy.
If humans hung upside-down from a tree for several hours, it wouldn't take long before they passed out. So how do bats manage it?
For starters, human and bat circulatory systems are fundamentally different. Because our blood pumps in the direction of our brain, the stress of gravity transfers even more blood to the head when upside-down. A bat's circulatory systems pumps the opposite way — away from its head. Also, while all mammals have valves in their veins that prevent blood from flowing backward, bats possess these valves in their arteries, as well. All of these adaptations ensure blood is evenly distributed throughout the bat's body.
It also just happens to be more energy-efficient for bats to hang by their feet. As opposed to defying gravity and standing upright, no energy has to be expended while hanging due to the lightweight structure of their leg muscles and bones that were developed for flight.
10. Bats are the only mammals that can truly fly.
While some mammals like flying squirrels, sugar gliders and colugos can glide through the air for short distances, bats are capable of true, sustained flight.
Unlike birds, which move their entire forelimbs, bats fly by flapping their webbed digits. The membrane of the wings is sensitive and delicate, and while it can be easily ripped, it can just as easily regrow.
11. Bats can have surprisingly long life spans.
Larger mammals tend to have a slower metabolism and a longer life span, but there are exceptions. Humans, for instance, live much longer than many other mammals that have a larger body mass — as do bats. In fact, according to a study in the journal Nature Ecology & Evolution, there are 19 mammal species that live even longer than humans, relative to their body size, and 18 of those species are bats.
The Brandt's bat, for one, typically weighs just 4 to 8 grams, yet it can live for 40 years. The study identified several possible reasons for bats' outsized longevity, including genetic traits that are already known to extend life span as well as novel genes that have not yet been linked with healthy aging.
12. Bats often share their homes with thousands of other bats.
The world's largest natural bat colony is the Bracken Bat Cave in Texas, which houses 20 million bats. Over the course of one night, the entire colony can consume a whopping 200 tons of flying insects. There are so many bats that when they collectively depart their cave to go foraging, a dense cloud of their bodies is visible on weather radar.
The site of the world's largest urban bat colony is in Austin, Texas, where up to 1.5 million Mexican free-tailed bats roost underneath the Ann W. Richards Congress Avenue Bridge. After spending their winters in Mexico, the bats migrate to Austin from March to November, during which time they put on a nightly show for residents and tourists eager to witness them taking off to forage for food.
13. White nose syndrome is wreaking havoc on America's bats.
In February 2006, a caver exploring Howe Caverns near Albany, New York, discovered white fungus accumulating around the muzzles of hibernating bats. The disease spread rapidly over the next several years, and is now documented in hundreds of bat colonies across North America.
With a mortality rate as high as 99% in some colonies, white nose syndrome is responsible for the deaths of at least 6 million bats. The fungus has been identified as Pseudogymnoascus destructans, but aside from some recent hints of hope, it remains an existential threat to many populations and species of American bats.
Unless scientists are able to find a solution, the little brown bat, the most common bat species in North America, is on track for extinction.
Editor's note: This story was originally published in May 2013 and has been updated with more recent information.