These articles were published in the Spectacular Slovakia travel guide, published annually by The Slovak Spectator since 1996. The latest editions can be obtained from our online shop.

A bat’s paradise

 photo: Chris Togneri

Slovenský raj is home to over 300 known caves, making it a haven for bats, those mysterious nocturnal flying mammals. But how many, exactly, are here?

“Only 10% to 15% of the caves have been checked, so I can’t say how many bats are here,” said Bedřich Hájek, a park zoologist. “But we have to find out. It’s very important because the more we know about the bats, the better we can protect them. If there’s a population crash, we need to know about it. Only then can we figure out what’s going on and how to solve it.”

In October 2001 a group of zoologists met in the park to discuss population survey methods, including tagging (or marking) the bats, the most effective way of measuring the population. But because tagging can be harmful, the group wanted to debate the safest methods.

Eli Fenichel, a former American Peace Corps volunteer who works in the park, is a proponent of tagging because, he says, bats often reflect local and global environmental changes.

“Bats are very sensitive to environmental changes because, for one, they are very small,” he said. “They could be severely affected, for example, by temperature changes in caves and forests. Also, some bats reflect water pollution because they prey on small fish or aquatic insects. So if their population drops, we know that something may be wrong with the local water sources.”

Furthermore, bats have high metabolic rates, meaning that chemicals or pollutants often kill them more quickly than they kill larger animals with slower metabolic rates, he added.

But Slovakia’s bats are not currently marked, in part because of the risk. Since bats are so small - without their wings, Slovakia’s average bat is no bigger than a mouse - strapping a tag to their fragile bodies can have deadly results. One outdated method was to strap a bracelet around the bat’s ankle. But if the leg was damaged during the process, the bat would die as it could no longer suspend itself upside-down to sleep.

Similar dangers exist with the ‘wing band’, a small hoop that pierces the bat’s fragile wing (a bat’s wing is so delicate that a human could effortlessly poke a finger completely through). The band can tear the wing, limiting the bat’s ability to fly and find food.

Radio transmitters strapped around the bats like a mini-backpack provide the most information, but are too expensive for the park’s budget. Moreover, they have short life-spans (four months) and thus provide little long-term information.

Slovakia’s bat experts would like to employ a different tagging method, one involving colour-coded plastic necklaces. The necklaces are cheap, safe, and allow the zoologists to differentiate between individuals.

But even this system has encountered problems. For one, the bands are not made in Slovakia. While a zoologist in Mexico has agreed to ship 1,000 bracelets for $150, the park has had problems transferring money from its Slovak bank to the Mexican account.

The only current form of tagging in Slovenský raj is done with the office supply product known as ‘white-out’. On the night of October 18-19, the group of zoologists caught bats outside Stratenská cave, home to over 2,000 bats, and one of the largest bat hibernation locales in central Europe.

Setting up a net approximately 10 metres long and 1.5 metres high outside the cave’s mouth high up on a cliff, the group waited silently in the dark for the bats to fly into the net. When a bat was snared, the designated bat handler freed the bat from the net and brought it to the head zoologist to record the species, sex and any curious markings (one had a hole in its wing).

The zoologist then applied a drop of white-out to the bat’s head. The mark, which comes off in a few days, lets the team know when they have recaptured a bat later that night.

Over a six-hour period at Stratenská cave, there were 80 catches (66 individuals). The most frequently snared was the Greater Mouse Eared bat (Myotis myotis) and the Natterer’s bat (Myotis nattereri). One of the prize catches of the evening was the Grey Long-Eared bat (P. austriacus), which is unique for its long ears curling back like a ram’s horns.

- Chris Togneri

These articles and related information were published in Spectacular Slovakia 2002.

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