BATS IN A FLAP
Brown long-eared bats tend to fly amongst trees
It’s officially spring. The birds are nesting, the sun (occasionally) shines and bats come out of hibernation and begin to get active. Bats spent much of the winter living off their fat in cool places. By spring their fat reserves are very low and it’s important that they build these back up again, as the females especially are in for a very busy time.
The male bats fatten up, flit about and hang about together in small numbers. The females have much more to do! Not only must they get healthy, but also they must find a cosy maternity roost. Most females will have a pregnancy to support and by June a hungry baby to look after. Bat mothers have one baby per year (twins do occur but are rare). At birth the babies weigh between a quarter and a third of their mother’s weight. That’s a lot of milk needed. Males don’t help to look after the babies (it’s no wonder females only have one).
All British bats feed on insects and our smallest bat, the pipistrelle, can eat upto 3,000 midges in one night (one-third of its body weight!). If you want to see bats, you should head for places that have a combination of water, woodland and wildflowers, as these habitats tend to attract lots of insects and provide an ideal feeding ground for bats. Watch along tree lines or hedgerows and by smooth flowing rivers or over lochans (providing you can do so safely). Another place you might see bats feeding is around streetlights or garden lights – lots of people tell us that they love to spend long summer evenings watching bats flitting around their garden!
The best times to watch for bats is the hour around sunset (after that the bats are still about but it gets too dark to see anything) or if you can manage it the hour before sunrise. However, if the weather is wild, wet and cold, don’t bother going out. Be like a bat and stay tucked up inside. On nights with poor weather there are unlikely to be many flying insects about so it’s just not worth their while for the bats to go out. As well as watching for bats, there are ways of listening for them. The best and most exciting way to hear bat calls is through a bat detector, this turns sounds we can’t hear into sounds we can. Sometimes the sounds are beautifully melodic and at other times highly amusing in a “rude-raspberry” sort of way. It can be amazing to tune in to the normally secret world of bat sounds and hear the night air full of bat music.
What bats might you see?
The first bats to emerge at night in the north west of Scotland are the pipistrelle bats. They have a jinking flight and tend to hunt over hedgerows. If you are seeing bats close to sunset its probably pipistrelles.
If you spot bats flying fast and low over water, then its pretty certain to be Daubenton’s bats. If you shine a red filtered torch over the water surface you may even see the bats causing ripples on the waters surface as they scoop up insects. (Using a red filter causes the least disturbance to the bats, don’t dazzle them with very bright torch light.)
The other bats that might be about are brown long-eared bats and Natterer's bats, although they aren’t so easy to spot. Both bats come out around 40-50 minutes after sunset. Brown long-eared bats tend to fly amongst trees and call so quietly that even on a bat detector it can be impossible to hear them unless you are very close. Natterer's bats do have one very clever trick, they will emerge from their roost and fly so low they look as if they are heather skimming.
If you would like to find out more about bats you can look on the SNH website www.snh.org.uk and the Bat Conservation Trust website on www.bats.org.uk. You can also find out how to take part in bat surveys and help bat conservation. If you spot bats in your garden or local area, why not take part in ‘From Dusk to Dawn’, the new garden survey from the Bat Conservation Trust? The survey is in two parts – firstly watch for bats in your garden around sunset to see which direction they arrive from; secondly try to get up before sunrise (preferably the next day, but no more than a week later) and head in the direction that the bats were coming from to see if you can find the roost. This survey takes place around 23rd and 24th July, contact BCT for more details.
Finally if you’d like to go on a bat walk and hear bats through a bat detector, watch the BCT website for a bat walk near you over European Bat Weekend (27th-29th August 2005).