Threats and Conservation
Text & illustrations © Conor Kelleher
What use are they? It's a question often asked about these harmless creatures of the night. It stems from a lack of knowledge of this particular group of mammals and the effect that all those horror movies have had on our conception of these animals. Whatever our misconceptions of the bat, most people are aware of its amazing flying abilities and the fact that its activity is confined to the hours of darkness. Amazing as these impressive flyers are, the truth about their importance to the environment and their peculiar lifestyle is only now being discovered.
There are approximately 980 species of bat currently known to science. They represent the largest group of mammals after the rodents, to which, they are not related. Their origins are unknown. The oldest known bat fossils are fully formed animals as we know them today and no clue currently exists as to what their ancestors might have been.
All bats are grouped in the order of Chiroptera (meaning hand-wing). There are two sub-orders, namely the Megachiroptera and the Microchiroptera. The mega, or large fruit eating bats, can have wingspans up to two metres and the smallest mammal in the world is a micro bat called the Bumblebee bat. The mega bats used to be grouped with humans and apes as they share certain characteristics of the primates and the micro bats, given the available evidence, may have been originally shrew-like creatures. This has led many scientists to think that these two groups may have had separate ancestors and so, may not be related. If so, one group isn't a bat at all! Therefore, we will have to await any future fossil finds to help to solve the puzzle of where bats originally came from.
Ireland is extremely important when it comes to these small mammals. We have the largest national population of lesser horseshoe bats in Europe. Our population of Leisler's bats is also of international importance. Because of this, Ireland has ratified two European conventions on bat conservation and is obligated under a third, the European Habitats Directive, to ensure that lesser horseshoe bat foraging areas are protected.
But what is so special about bats anyway? In truth, they are highly specialised creatures and, because of this, they find it difficult to adapt to the changes in the modern countryside. They are the only mammals capable of true flight. Each species has adapted to hunting in a different manner, whether it is in open air, hovering to pick an insect from a leaf or pouncing on their prey on the ground. All our bats eat only insects and spiders. The Common pipistrelle, with which everyone is familiar, can catch up to 3000 midges a night! Every night. There is nothing else feeding on night flying insects and as the bats are decreasing in numbers, the amount of insects, including pests, is growing. It is estimated that bat numbers across Europe have fallen by up to 60% in the last 15 years.
However, in order to save any creature, the first thing one has to do is learn what you can about its habits and lifestyle and what it needs to survive. The study of bats is relatively new. It began in earnest during the late sixties, mostly by amateurs. Slowly, the intimate secrets of these maligned animals were revealed:-
- A fully grown pipistrelle weighs as little as a penny and fits in a matchbox!
- Bats are more closely related to humans than they are to mice!
- Bats have only one baby per year, sometimes only one every two years!
- Bats have better eyesight than humans!
- Bats do not get caught in your hair!
- Bats seldom live in belfries!
In fact, most of what we thought we knew about bats turned out to be wrong. We are only now realising that these creatures are extremely important to the environment in a worldwide sense. Tropical bats are responsible for 98% of the regrowth of rainforests through seed dispersal. Birds tend to deposit seeds beneath existing perches so any bare ground first needs to be seeded by bats as they pass over. Once the initial growth begins then the birds can do their bit.
Bats pollinate many important fruit trees such as banana, fig and durian. The latter, alone, is worth over $120,000,000 a year to the Malaysian economy. These trees only open their flowers at night so that nectar feeding bats will visit them. Many of these plants have evolved in unison with a single species of bat, the shape of the bat's head being an exact fit to the type of flower produced, if the bats become extinct so too does the tree.
Guano, the bats' droppings, are also valuable as a fertiliser. The sale of bat dung from a single cave in America fetched $6,000,000. It isn't just in America that bat droppings are regarded as commercially important, faction fighting amongst opposing guano gangs broke out recently in Asia and several people were killed defending 'their' guano caves.
The importance of bats doesn't end there, the most famous, or infamous, bat of all, the Vampire is being studied at present as it was discovered that its saliva contained an anti-coagulant which is being used to help haemophiliacs. Even Vampire bats have been given a bad press over the years. There are actually only three species, all found in Central and South America, and, contrary to popular belief, they do not suck blood but lap it. Two prey on roosting birds and are almost extinct. The third feeds on large mammals, including man, if he's silly enough to let his big toe protrude from under the covers at night! These three species have been relentlessly persecuted by local landowners who dynamited over 6,000 caves in one campaign alone. The irony is that, unknown to the farmers, most of the bat species destroyed were helpful seed dispersers and plant pollinators. However, Vampires are a long way from Ireland!
Irish bats, too, are under pressure. These creatures face a range of threats in our own country. The main factors for the decline of bats in Ireland and the rest of Europe are:
- Destruction of habitat: loss of woodlands and hedgerows.
- Destruction/renovation of roost sites e.g. houses, caves, mines, trees.
- Reduction in food sources: lack of insects due to pesticides and insecticides and the use of worming chemicals in cattle, such as Ivomec (Ivermectin), which inhibits insect development in the cow pat.
- Poisons absorbed while preying on insects sprayed with chemicals.
- Disturbance and killing of bats by people.
- The use of timber treatment poisons within roof spaces which are used by bats.
Irish bats are very clean animals, they regularly groom and seek out clean places in which to live and they carry no known diseases. They don't even like cobwebs! They do not bring in nesting materials, rather they just crawl into crevices or hang from whatever is available. As they are not rodents, they have no front teeth so they do not gnaw wood or electric cables. Their use of houses is seasonal, rather like swallows; they usually arrive in April and leave in September or October.
Having only one baby a year, they really look after it and are quite good mothers. We don't know how long the infant spends with its mum but they have to be introduced to all the best feeding areas and roosting sites so it may be quite some time. The first year of a bat's life is fraught with danger as it has to learn to fly, to avoid predators like owls and cats and it has to put on enough fat to see it through its first winter's hibernation. Most don't make it. The average lifespan in the wild is four years. However, in captivity, pipistrelles have lived up to 16 years and larger bats up to 30! This is quite remarkable for such a small creature but the slow rate of reproduction has to be taken into account.
All bats and their roosts are protected by law and a licence is needed to disturb them in the wild. Currently, we have nine known species in Ireland and a further two species recorded on bat detector only, bringing our total to a possible eleven species. There may be even more out there awaiting discovery but, up until now, there have been very few people interested in these timid creatures so the individual species has often been overlooked.