Search for bat species in flight

I SAW the first bat of the year on the wing on the evening of April 22.

This is unusual. In the cold part of the midlands that I live in I have previously never seen them in flight before May.

But April 22 was just at the end of the five-week spell of fine weather. I presume that the high temperatures tempted it out of hibernation a little earlier than usual.

It was a Pipistrelle, I could tell that by the small size. But there are now known to be three species of Pipistrelle breeding in Ireland and I couldn’t tell which of the three it was because I don’t own a bat detector.

A bat detector is, of course, an electronic device that analyses the frequency of the squeaks a bat uses for echo-location which gives a precise identification of the species.

The widespread use of bat detectors over the past decade has resulted in a very surprising development in Irish mammal zoology. Any book or reference source written before the mid 1990s will state confidently that Ireland has seven native bat species. We now know that there are ten and the list could continue to grow.

It really all started in 1997 when a species called Nathusius’ Pipistrelle, which is quite common in the rest of Europe, was discovered breeding in Northern Ireland. Since then it has also been recorded by detectors in the Republic.

Around the same time British scientists studying the Pipistrelle discovered that it was actually two different species. These have been called the Common Pipistrelle and the Soprano Pipistrelle (it has a higher pitched squeak). It was discovered that both species are found in Ireland.

That brought the seven species up to nine. The tenth was Brandt’s Bat, which is very similar to a Whiskered Bat and had probably been confused with it in the days before bat detectors. A single specimen was identified in Co Wicklow in 2003.

At first it was thought that this was a vagrant that had blown in from Britain or continental Europe. But since then Brandt’s bat has been found breeding in many other parts of the country. The first site was in Co Clare and the most recent one, last year, was in Co Tipperary.

The bat hunters are now in pursuit of other species that could be added to the list of Irish native mammals over the next few years. The two most likely candidates — there are already some reports of them — are the Noctule Bat and the Barbastelle Bat.

BAT DETECTORS are not infallible and bat identification is a tricky business. They can be caught in mist nets of the type that bird-ringers use but they are very delicate and easy to damage. They also have a tendency to die if they’re disturbed during hibernation.

The best way of identifying them is from the body of a bat that has died from natural causes. If you come across a bat corpse, particularly an unusual looking one, the good people in Bat Conservation Ireland would be very interested in hearing from you.

The conservation of bats is actually a worrying business because, although we’ve been adding species to the Irish list every few years recently, total bat numbers are declining quite rapidly around the country. The same is true over most of Europe and some of our remaining populations are now of international importance.

The usual reason given for this is a decrease in the winged insects bats feed on because of farmers using pesticides. But I’m not sure farmers are to blame in Ireland because they actually use very few insecticides. In fact, though I don’t have figures to back this up, I suspect gardeners buy more insecticide than farmers these days.

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