Sunday, June 24, 2012

It's all bats, really

Bat Night 2012

Do you dislike bats, or even the notion of them? Don't, writes Brian Byrne, because without them we'd be overun by insects. Each bat consumes around 3,000 bugs in a night's feeding.

That was just one of the fascinating facts revealed at Friday night's Bats Talk & Walk event in Kilcullen's Wild Weekend programme. 'Batwoman' Dr Tina Aughney of Bat Conservation Ireland also told an audience of more than 70 that some bats are 'the bumble bee of the night'. Without the 'only true flying mammals in the world' many species of plant wouldn't be pollinated. Which would mean we'd be short of lots of fruits, like bananas.

In fact, the various activities of bats have even been given a monetary value. "A recent published study says that bats save the US agricultural sector some $22 billion a year," she noted.

The event was part of the Biodiversity Survey currently being conducted by Dr Mary Tubridy on behalf of Kilcullen Community Action. It will result in, among other things, useful information for a Nature Trail along the river. But Friday night had just one focus. A range of mammals which number some 1,100 different varieties around the world, around 46 of which exist across Europe, and in Ireland there are just nine types.

Bat Night 2012

The audience in the Bridge Camphill Hall was about half-and-half adults and children, and so it was to the little ones that much of the evening was directed. Tina debunked the myths first, including the ones that bats are related to mice, that they can get tangled in your hair, and that they'll infest your home if they take up residence.

"In fact, they don't reproduce much, maybe one baby every two years," she said about that last. And even though a baby bat will grow to adult size in about six weeks, the mother can stay with her offspring for up to two years, making sure it learns to survive, hunt and fly. "In August you can see them skimming across the river on the hunt for insects, often the baby first followed by the mother."

Bat Night 2012

Bats will roost in many places, but do so especially near water because that's where insects breed and so there'll be food. Which is why bridges like the one in Kilcullen are favoured. So are older houses, although Tina Aughney quipped that the current 'ghost estates' are likely to be populated much faster by bats than by people. Still, it hasn't been a good year for the species. The weather is all wrong, the cold, wind and wet upsetting the insect population and therefore the food supply.

Of the nine resident bat species in Ireland—all of which are in the 'microbat' or very small category—there are about six in the Kilcullen area. Each has quite distinctive characteristics, especially in their sounds which are used to seek prey and avoid obstacles using a 'sonar' sound reflective system.

Special electronic 'bat detectors' are used to find and track them, each kind recognisable by their own sound frequency. "Bat sounds are mostly higher than humans can hear," Dr Tina said. "Though some children can hear species that use lower frequencies, adults just can't."

She detailed the complexity of the systems, noting how they can work out the eatibility, location, speed and trajectory of insects simply from the reflections coming back. "There's a level of mathematics there that we simply can't do. One kind of bat, the Brown Long-eared, can locate a moth by hearing the flutter of its wings." And the same moth has developed an avoidance of becoming lunch or dinner by literally dropping to the ground and 'playing dead'.

Bats have long been a protected species, but there's real concern about them at the moment. A 50 percent decline in the insect population across Europe is one issue, but the biggest 'stress' is destruction of habitat.

"This can be related to the effects of development, but farm hedgegrows and treelines are very important to bats as they travel in search of food. And while bats love to live in old trees, these days we cut down dead trees with holes in them, for safety reasons."

Then there are predators. Barn owls, for instance, though as they are themselves a protected species, they're not deemed to be a significant problem. Domestic cats are. "We have known of very clever cats who can gobble up bats as they fall out of roosts preparing to fly," Dr Tina said, suggesting that cat owners should always keep their pets in at dawn and dusk. "A single cat can kill off a complete roost."

At the end of an informative and very entertaining presentation, the event was thrown open to questions. The best, and most, came from the children. 'How do they not bump into each other when they swarm?', 'When do they come out?' (depends on the species, and their timings from sundown are predictable to the minute), 'How long does it take them to digest an insect?', 'How much bones in a bat's body?' being just a few. And Dr Tina had to admit to not having all the answers. "I'm getting scared of the questions now," she grinned at one point.

Bat Night 2012

The talk part concluded with the youngsters being given dead bats of different species to show to their parents (and guess which were the more squeamish?). After that it was a walk down through the dusktime Valley Park with bat detectors and sharp hopeful scanning of the between day and night sky.

Bat Night 2012

Detectors crackled, bats were spotted, and everybody eventually went home happy. A magic of nature had been revealed, spells were woven, and knowledge was transferred.

Friday nights don't come much better, really.