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December 2001
Townsend’s big-eared bat, Corynorhinus townsendii, a fruit bat. Source: Nevada Bureau of Land Management.
Introduction
Bats are not only fascinating mammals but they are of great importance in nature. Bats have been on this planet for over 50-60 million years. There are between 950 to 1,000 species, living on all continents except Antarctica. The small microbats eat mostly insects whereas megabats, the larger-sized variety, feed mostly on fruit. Sometimes, both small and large species eat flowers and drink nectar.
increased use of pesticides, both in agriculture and in the treatment of building materials against pests, which in turn poisons the bats who consume them3
disturbance of colonies, particularly by people exploring caves in winter; human presence disturbs hybernating bats, causing bats to lose their energy and leading to exhaustion and death
extermination — millions of bats are killed due to myths, superstitions and misinformation
hunting — a large number of bats are used for commercial purposes, such as sales to museums, biomedical research institutions, or in some Third World countries as food In the last few decades bat populations have been declining at alarming rates worldwide. Bats remain the most endangered land mammal in the United States.1 The International Union for Conservation of Nature and Natural Resources listed 53 bat species as endangered and at least that many more species at risk in 2000.2
Bats on the decline
Humans are the main cause of bat declines and extinctions. The causes for decline include:
- habitat loss through such activities as deforestation, elimination of foraging areas, roost and cave destruction
Reasons for protection
Balance in nature
Bats are the primary predators of night-flying insects, playing a vital role in maintaining their balance in nature. One bat eats 1/3 of its body weight and is able to catch 600 mosquitoes in one hour. Their instinct to live in colonies ensures that large numbers of bats will live or relocate to areas where there are lots of insects, keeping insect populations down. And different bat species hunt at different heights, preying on different kinds of insects. The big-sized bats eat various moths and worms that are harmful to agriculture and forestry. The small-sized bats eat mosquitoes and other double-winged insects - - carriers of diseases such as malaria and leischnamia. This is one reason to protect all species of bats.
Helping the world’s flora
Bats that eat fruit or flowers disperse seeds and pollinate flowers of more than 500 species of tropical trees and shrubs. With their help, humans are supplied with a large crop of bananas, cashews, avocados, balsa wood and tequila. If it were not for bats, the harvest of such tropical fruit as bananas and pineapples would decrease by 60%.
Natural fertilizers
Guano, or bat droppings, is the highest quality natural fertilizer. It contains much more nitrogen and phosphate than other natural or artificial fertilizers. In addition, guano in caves supports entire ecosystems of unique organisms, including bacteria useful in detoxifying industrial wastes and producing antibiotics.
Bat myths
- Bats do not have a high incidence of rabies (less than 0.5%). But if a bat allows you to approach, it is probably sick and should be avoided.
- Bats flying over your head are not trying to attack you. They are catching insects that are attracted to you.
- Vampire bats prefer farm animals such as cattle or birds to humans.
- And the last and most important: bats never get tangled in people’s hair!
Bats in Georgia
The Caucasus Mountains of Transcaucasia attract researchers because of their unique landscapes, flora and fauna. Located between the Black and Caspian Seas, they are home to a particularly diverse array of bats, a result of south, east and west faunal migrations. Of the 37 species of bats observed in Europe, about 29 can be found in the small territory of Georgia.4
The status and population trends of bats in Georgia are unknown.5 The reason for the lack of information is that they are very complicated animals to study. As well, bats have never been popular subjects for special study and accordingly there has never been any Georgian scientist researching them. I am sure that local extinction of some species has already occurred.
So, I decided to study bats in my country, Georgia.
- I investigated different bat shelters at different altitudes for a whole year, at night and by day. I investigated 498 shelters and found bat colonies in 444. Some of the colonies were very small.
- I also studied different biotopes to discover as many species as I could. For identification I applied 6 different criteria. I found only 8 species. Two of them are on the red list of endangered species. My research suggested that three more were at risk.
In Georgia, the low biodiversity of bat species is due, on the one hand, to urbanization which reduces their hunting areas and, on the other hand, to the extermination of these animals by people. Some people willfully exterminate bats, often because of a disturbing cultural myth. Some religious leaders have convinced people that bats have an evil origin. Others destroy bat roosts during the restoration of old buildings. In Georgia, pesticides are not a problem for bats, since no pesticides are used in timber treatment, and very seldom pesticides are used in agriculture.5
The most difficult task in my research was to find forest species. Georgia has an energy crisis and forests are being cut down for fuel without sufficient conservation management policies in place. There is a widespread misunderstanding that cutting trees with hollows doesn’t harm the environment. In reality, many bats live in tree hollows. That’s why it is very important for Georgia to protect old trees with hollows, because these endangered species live here.
Bat conservation
More than 50% of bats do not survive infancy. A female usually has only one offspring a year, so population recovery is slow. Declining populations can only be stopped through tough measures. Public education is also important, especially in developing countries, through such efforts as financing conservation-oriented studies and distribution of scientific literature about bats.
I hope more people will become interested in bats and take action to protect them. For example, one way of helping some species of bats is to build an artificial hollow to shelter bat colonies. Compared to natural hollows, the artificial version has less parasites and humidity. This makes the conditions better for survival, especially for newborn bats.
Bats are creatures of the dark but it doesn’t mean that we should leave their problems in the dark as well.
© 2001, American Institute of Biological Sciences. Educators have permission to reprint articles for classroom use; other users, please contact editor@action bioscience.org for reprint permission. See reprint policy.
