Bats are mammals of the order Chiroptera whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. Bats do not flap their entire forelimbs, as birds do, but instead flap their spread-out digits, which are very long and covered with a thin membrane.
They are the second largest order of mammal after rodents, with about 1,240 bat species divided into two suborders: the less specialized and largely fruit-eating megabats, or flying foxes, and the highly specialized and echolocating microbats. It is known that 70% of bat species are insectivores, with the other 30% feeding on fruits, on other animals than insects, or the vampire bats that feed on blood.
Except for very cold regions, you can find bats throughout most of the world. Although some of them have vital roles in ecology, such as pollinating flowers and reducing the number of insects, some bats are considered pests themselves, as they can easily transmit disease.
Diversity, behaviour and reproduction of bats
As previously mentioned, bats can be divided into two classes. The Megachiroptera (megabats) eats fruits, nectar or pollen, while the Microchiroptera type (microbats/echolocating bats) eat insects, fish, frogs, small animals or even the blood of other animals. Megabats have well-developed visual cortices and show good visual acuity, while microbats rely on echolocation for navigation and finding prey.
Due to the diversity of their feeding habits, bats can be found in almost every habitat available on Earth. Different species choose different locations and different seasons, however all have two basic requirements for a hospitable dwelling place: roots on which they hibernate, and places meant for foraging.
The United States alone is home to around 45 species of bats, with the most common being:
- the little brown bat (Myotis lucifugus);
- the big brown bat (Eptesicus fuscus);
- the Mexican free-tailed bat (Tadarida brasiliensis).
All bats have small, razor-sharp teeth and a long tongue. The eyes will depend on the species; in most microbats, they will be small and not very well developed, while in megabats, they will be large and offer high-quality vision. Bats also have a nose, which is usually small, but which has an excellent sense of smell.
The surface of a bats’ wings is equipped with touch-sensitive receptors (which are also found on human fingertips), allowing the bat to collect information regarding the environment, and essentially also allowing it to fly more efficiently. Bats also have very short legs, with knees. The toes have claws that help in gripping and, thus, allows the bats to be able to hang upside down: their normal resting position. The entire body of a bat, with the exception of the wings, will be covered with fur, which will help keep it warm.
The smallest bat is the Kitti’s hog-nosed bat, measuring around 30-34mm in length and 15cm across the wings, and weighing around 2-2,6g. The largest bats belong to the species Pteropus; the giant golden-crowned flying fox measures around 1,7m across the wings and weighs up to 1,6kg.
In terms of behaviour, the bats are nocturnal and are active at twilight. Most species migrate to winter hibernation dens, while the rest pass into torpor in cold weather, rousing and feeding when warm weather allows for insects to be active.
Some species of bats are solitary, while others live in colonies that can number up to a million bats. Most species have a breeding season, usually in the winter, and they can have up to even 3 litters in one season, should the conditions be favourable. Female bats use a variety of strategies to control the timing of pregnancy and the birth of young, to make delivery coincide with maximum food ability and other ecological factors. Females of some species have delayed fertilisation, in which sperm is stored in the reproductive tract for several months after mating. All of these adaptations result in the pup being born during a time of high local production of fruit or insects.
At birth, the wings are too small to be used for flight. Young microbats become independent at the age of six to eight weeks, while megabats do not until they are four months old. Generally, bats can live up to 20 years. Some species, however, have been recorded to live well over 30 years in the wild, however population growth is limited by the slow birth rate.
While newborn bats feed only on their mother’s milk, bats that are a few weeks old are expected to fly and hunt on their own. As the majority of species are nocturnal, they hunt at night. In a series of experiments in the 1790’s and then in 1930’s, the fact that bats use echolocation to be able to hunt in the dark started to be unraveled.
Those species that consume insects, frogs or lizards can become convenient for humans in the area. Also, bat faeces are high in nutrients and it is used for farmers to fertilise their crops. Bats fulfil important ecological roles, by pollinating flowers and dispersing fruit seeds, as well as consuming pests, thus being economically important by reducing the need of pesticides. Due to this aspect, a lot of laws and conservation efforts have been initiated.
However, bats do become a problem when they start to nest in places where they do not belong, such as your attic, your chimney, and even your walls. Not only are some people naturally terrified of them, but they also make bothersome noises, such as squeaks and scratches, and the dust from their faeces can prove very dangerous if inhaled. They also carry flees and mites and it has been discovered that they can also carry rabies and even Ebola, becoming thus a serious threat for humans. This is why learning how to get rid of bats becomes imperative.