Nature Notes

Brin Best

Wharfedale Naturalists’ Society

FOR the last week everybody in our household has been going completely batty after tea. I can assure you that this is not normal for the Best household, because the reason for our recent battiness is a week-long count of the mysterious furry mammals which come out at night to fly around our neighbourhood.

Our location, on the very western fringe of Otley, seems ideal for bats. Our own and our neighbours’ gardens attract moths and other insects which the bats like to dine on. And just over the road is a large network of fields, interspersed with groups and avenues of trees, which provide perfect foraging opportunities for the furry ones.

The first of the three bat species we see on a regular basis - the noctule bat - comes out just as the last insect-eating birds are heading to roost. This means that there is an overlap during which swifts, swallows and house martins are on the wing at the same time as the early-emerging noctules.

Noctule bats have a wingspan almost as large as a starling. They have an agile, purposeful flight action, propelling themselves forward with eager little wing movements. These impressive bats often stop in their tracks and backtrack, after detecting prey through echolocation.

Our noctules probably raise their young in old trees in the nearby Eastwood, and we sometimes see them coming from that direction in a little procession, one after the other.

As the light diminishes further two smaller species emerge: the medium-sized Natterer’s bat and the teeny tiny pipistrelle. They make their homes in the roofs of the houses on our street, finding secluded places to hide away and raise their young. Bats do no harm to our houses and are fully protected by British law.

The Natterer’s bats in our neighbourhood seem to have a slower and more deliberate flight action than the other species, often following a tree line. The pipistrelles, by contrast, are real acrobats. They undertake impressive aerial manoeuvres as they hoover up small insects.

Our peak count so far is 18 bats in one night. That occurred on a still and fairly warm night when insects were on the wing in abundance. As the year progresses so the young bats will take to the wing and we are likely to see the numbers in our bat counts rise.

Watching bats is so much fun and I can heartily recommend it. Why not get batty yourself next week?