Bats as we all know are nocturnal which means they need somewhere to hold up during the day to hide from predators and have a well earned rest from flitting about echolocating and feeding on moths. And during the times of year when they are not in huge communal roosts in caves many bats choose holes in trees. These holes provide very stable conditions - stable temperature, humidity and shelter from wind. A pipistrelle can weigh as little as 3.5 grams (and that's an adult) so you can imagine they get cold quickly if things aren't perfect.
Bat boxes can go some way to providing roosting sites but the research shows that natural sites are much more likely to attract these little flying mammals and so isn’t it best to protect nature’s very own boxes rather than simply relying on our own?
The bats will often return to the same tree year after year to roost and so its very important to retain ancient bat roost sites like those in veteran trees, particularly as individual bats can live for upwards of 30 years.
Different species of bat require different habitat to hunt in but woodland is often the most diverse. Woodland provides food sources in the form of flying insects, particularly moths which bats can pin point with milimeter accuracy in pitch darkness using their echolocation – this skill is so finely tuned that bats have a process called flutter detection where their echolocation can detect the rhythmic movement of wing flpping back and forth which distinguishes a tasty meal from something useless like a leaf gently drifting on the wind. Veteran trees provide perfect habitat for these flying insects, particularly their larvae which feed on both living leaves and on rotting wood and fungi held on and in the tree. Many of these woodland moths also require veteran trees to survive because they need hollows and holes to provide shelter for them and their young during the day.
Next week I’ll look at some more mammals that need veteran trees as both a bedroom and a dining room.
This week I’m straying from the format a little and going for some bat based trivia: the Mexican long nosed bat is the only animal that pollinates a group of plants known as the century plants. These plants are distilled to produce tequila. So without bats you could say goodbye to margaritas and tequila sunrises alike.