There are about 1,000 bat species in the world, and they make up almost a quarter of all modern mammal species. Thanks to the ability to fly, bats have spread to almost every corner of the world. Their range covers all continents except Antarctica and all climatic zones except tundra, polar regions, as well as some oceanic islands.
Although bats are quite common in areas where industry and agriculture are heavily developed, their populations have declined significantly and many species are now on the verge of extinction. The science that studies bats is called chiropterology.
The body length of bats, depending on the species, is from 2.5 to 14 cm. They see well, but with the help of ultrasound they orient themselves in space: they release position signals in the form of short ultrasonic pulses.
Almost all bats are nocturnal and sleep during the day. Due to the special fragile structure of the bones, bats are completely defenseless on the ground. For example, they cannot move on their feet and push off the ground like birds. This is why bats sleep upside down during the day. This position allows them to start flying directly during the fall.
Bats often make comfortable shelters by hiding in cracks in trees, rocks or crevices in buildings. Gaps in trees, caves, grottoes and various artificial structures, both underground and underground, can serve as shelters.
Bats can fall into lethargy, accompanied by a decrease in metabolic rate, respiratory intensity and heart rate, most of them enter a long seasonal hibernation (up to 8 months).
Due to the ability to regulate the metabolic rate, many insectivorous bats can go without food for a long time, but due to the large area of the wing membranes, they quickly lose moisture, and without free access to water, they die from dehydration.
In the active state, bats, like all small mammals, have a very high metabolic rate and accordingly require large amounts of food. On average, an insectivorous bat eats about a third of its own weight per night.
Most eat insects, but large bats (for example, a giant evening) can eat birds, lizards, frogs, a few fish. In South America there are three species of bats (vampires) that feed on the blood of vertebrates – birds and mammals. Some species are herbivores: they feed on fruit, nectar or pollen, such as fruit bats (for example, leaf bats).
Bats' natural enemies are mainly diurnal and nocturnal active predators: mainly cats, birds of prey and owls. There are also many large carnivorous bats that prey on small bats in the hunting process.
20 facts about bats
- Choosing the only possible type of structure for active flight, bats haven't changed much in their appearance and other characteristics over the past few tens of millions of years.
- Bats are the only group of mammals capable of continuous active flight. The length of the fingers, between which the flying membrane is stretched, is equal to the length of their body.
- One of every two bat species in our fauna makes seasonal migrations by flying south for the cold winter period.
- Bats give birth to only one, rarely two offspring.
- With their small size, bats live up to 10-15 years, which compensates for their low fertility.
- Bats stay upside down: they sit in a crevice or grab the claws of their hind limbs on small ledges of their "roosts".
- Most bats run well on the ground, and their dark paths with scum in the narrow passages of the caves are clearly visible.
- Bats are the only group of mammals capable of hypothermia: at daily rest, they enter a state of deep physiological sleep by lowering their body temperature to ambient.
- Bats begin their hunt by visiting a pond; on dry days, a small bat weighing 5-8 grams drinks up to 1 ml of water per day, compensating for the great loss of moisture from flying skin membranes.
- Bats often choose caves for their wintering, as temperatures are always above the freezing point of water and relative humidity exceeds 70%.
- Bats see with their ears: they emit a series of ultrasound at frequencies of 20-120 kHz, detecting the echo and distinguishing objects 1-10 mm in size. This allows bats to fly in the dark and see insects.
- An insectivorous bat can eat up to 200 mosquitoes in one hour of hunting. During the day, the bat eats insects up to 2/3 of its total weight, catching them in flight or preying on tree trunks. In one summer, a colony of one hundred eats up to 700,000 insects (many of which are agricultural and forest pests), a large colony can destroy more than 10 million insects.
- During the breeding season, most bats move from cool caves to warm caves, burrows and other roosts, and females only form groups of females – brood colonies.
- Bats mate in late summer or autumn, but the development of the embryo only begins in the spring, with the onset of warm days.
- In a cave hall the size of a one-room apartment, several hundred bats of several species may hibernate; In a hollow of an old tree, a brood colony of several dozen bats can be found.
- Bat species can be distinguished by their photographic portraits (especially the details of the structure of the ears) and the measurements of the wings – signs of adaptation to flight.
- Bats are the most sensitive group of animals to environmental changes, indicators of species richness and abundance, indicating the degree of protection or pollution of any land area.
- Bats are the most vulnerable group of mammals: for example, all European bat species are protected by the Bern Convention, and all Ukrainian bat species are listed in the Red Book of Ukraine.
- Bats are the only domestic mammal group that actively uses architectural and various engineering structures for their shelters, and some bat species have become widespread in cities.
- Bats are a natural reservoir of rabies and, according to the WHO, Marburg, Ebola and coronaviruses, which are part of a particularly dangerous group of infections. There is evidence that bats are involved in transmission. There are opinions that from bats (directly or indirectly) humanity has been infected with the global COVID-19 virus, the most dangerous infection today.
Use of ultrasonic signals by bats
to navigate in space
Bats detect objects blocking their path by making sounds that humans cannot hear and by catching their echoes reflected from objects. Before the discovery of ultrasonic echolocation, bats were thought to have extrasensory perception. Deprived of their sight, their wings were covered with thick varnish so that they could not feel the air currents, and yet they avoided the obstacles in the experimental chamber.
Studies have shown that when exploratory ultrasounds are emitted, the muscles in the bats' ears close the auricle to avoid damaging the hearing aid.
In bats, echolocation differs between families. In other words, horseshoe bats emit signals through their noses, and flat-nosed bats through their mouths.
Bats can detect a wire obstacle at a distance of 17 meters. The detection range depends on the wire diameter. Thus, at a distance of 0.4 meters there will be a wire with a diameter of 4 mm, and from 0.08 cm - 50 mm. However, the mouse responds not only to the thickness, but also to the length of the wire, as a result of which, with a sufficient segment length, the wire will be detected.
To contact relatives
In flight, bats sing songs at high frequencies using complex syllable combinations (due to their echolocation abilities). They generate ultrasonic waves between 40 and 100 kHz.
When looking at a female, each male sings his own song, but in general the melodies of all songs are similar in their order, which can be conditionally divided into three stages: “squeak”, “trill” and “itch” (if any). Try to describe them in terms of human perception). The difference lies in the individual combination of various syllables, the syntax of sentences and individual speech turns and the order in which they are formed. The female, on the other hand, can both reciprocate and reject the boyfriend's courtship.
Complex voice messages are used not only for dating, but also for describing each other, indicating social status, determining spatial boundaries, disagreements over hunting and the distribution of hunting grounds, breeding offspring, and resisting individuals invading someone else's territory.
In flight, rats use their ultrasonic communications to voice control air traffic safety in real time, to avoid a collision, ordinary rats need to correct their flight path and give way to a socially superior mouse.
According to biologist Michael Smotherman, no mammal other than humans is capable of communicating using such complex vocal sequences. The sound center responsible for arranging complex syllable sequences is slightly higher in bats than humans, and scientists have yet to determine exactly where it is.
for hunting
Bats that feed on fish (such as the Mexican fish-eating mouse) patrol the water surface at night, emitting very strong echolocation signals. But these signals do not penetrate the water column. The mouse does not detect a fish underwater, but it will immediately find even a small part of the fish's body if it comes out of the water.
It should be noted that echolocation does not always help bats find food. Some insects manage to hear the squeak of bats from afar and thus escape. And butterflies from the bear family send response signals to nocturnal predators, where they show their invincibility or try to hide their position by drowning out someone else's signal.
