Bats wake up to new threats

Dusk. We are sitting on a canal bank beside an 18th-century bridge. The date 1784 is carved into the beautifully weathered old stone. A thick blanket of ivy falls down its sides. It is an ideal place to observe the Daubenton's bat, a tiny hunter given to aerial hawking - catching insects on the wing low over water. Ireland's small but significant population of the only mammal capable of flight is now awake from its winter hibernation, itself a remarkable process influenced by the cold weather's lack of insects. Bats hibernating in a mine and covered in condensation were found to be so cold they could have been dead. Instead, they were ticking over on energy stored up during autumn feeding. Some bats don't move very far in winter, exchanging their summer roost in an attic for the basement in the same building. Irish bats favour buildings, roofs, stonework and hollow trees for their winter sleep.

While the birds take charge of the skies by day, the bats come into their own at night. The darkness heightens the sense of mystery surrounding their rituals. Once you begin watching them, interest may become an obsession. Bat watchers who started out as youngsters invariably remain fascinated into adulthood. But most adults lose the ability to hear, unaided, the high-pitched squeaks and clicks with which bats locate insects, and must use a bat detector.

Bats are internationally protected under the Bern Convention - and in Ireland are also protected under national law, listed in the Irish Red Data Book, which gives guidelines for conservation and protection. However, they are still in constant danger from the use of organochlorine preservatives in attic timbers and the decline in insect populations due to habitat change and the use of pesticides.

The lesser horseshoe bat, named for its complex nose structure and known for almost concealing its body in its wings, is largely confined to the west of Ireland. It is decreasing in numbers. The present population of whiskered bat, one of Ireland's rarest mammals, may now be under 1,000.

Bats are also much maligned, wrongly dismissed as disease-carrying, flying mice - they are not rodents, although a few countries still consider them to be vermin. Nor are they the blood-sucking monsters of Eastern and Central European myth. While they have little or no interest in getting tangled up in your hair, they do have a hugely important conservation role in insect control as well as in pollination and seed dispersal. Certainly they pay the price for being "interesting-looking" rather than conventionally cute or pretty. They don't live in belfries, either, although the beautiful Clonfert Cathedral in Co Galway is a roost for at least four species, including the quite rare white-bellied Natterer's bat.

ACROSS the world there are 990 species of bat, or Chiroptera, divided into two types: Megachiroptera, (big bats) feeding mainly on fruit and nectar, and Microchiroptera, (little bats), most of which are insect eaters. The nine species breeding in Ireland belong to the latter group. And Ireland's bats are small, their bodies barely longer than the average adult thumb.

Among our nine species are three varieties of Ireland's commonest bat, the pipistrelle - each distinguished by the sound frequency of its call. The Daubenton's, a water bat, is medium-sized with a pinkish face and short, rounded, dark-brown ears. Not a particularly frantic flier, its flight pattern is steady. It is quite common - and easy enough to sight if you're patient.

Even by the elusive standards of most wild animals, bats are discreet creatures of habit. In Ireland they tend to emerge from their roosts in old buildings, from under bridges or from old stone gate piers in ones and twos, never quite creating the drama of seeing them burst from caves in their thousands as they do in parts of North America and Asia. Breeding colonies of more than a million bats are common in various parts of the tropics.

On the canal bank, we see Daubenton's bats flying low, less than one metre over the water. They prefer it calm, without ripples because such movement makes it difficult to locate insects.

They catch them with their feet, and at times use their tails as scoops. Plop. These little low fliers can briefly end up in the water, but recover quickly and return to flight.

On summer evenings, Daubenton's bats are easily visible, busy catching midges and flies. Although feeding is as serious a business for bats as it is for everyone else, there is an aura of deliberate frenzy about these meticulous creatures hunting in squadrons. Daubenton's bats may share summer quarters with the most easily identifible of Irish bats, the brown long-eared "whispering" bat. Its ears are almost as long as its body.

This is a bat that might well spend almost an hour flying around its roost before emerging in darkness to forage in the vegetation of woodland and shrubs, perhaps even in your garden. It roosts in small groups of up to 10, and at rest those long ears are neatly tucked away. As it favours hollow trees for hibernation, it is vulnerable to habitat loss. It also falls prey when foraging on the ground to alert domestic cats as well as owls on patrol.