Posts Tagged ‘bat’
Posted on July 27, 2009 - by Denise
I find identifying quite difficult for two reasons. Bats fly so fast that it’s quite hard to get a mental snapshot and they don’t usually come out until dusk. However, my bat identification is slowly improving and here are the things that I think are useful to look for:
Note: there are 17 species of bat in the UK. I will concentrate on the most likely to be seen.
Size of body:
- Small (3-6cm): Common Pipistrelle; Lesser Horseshoe; Brown Long-eared; Daubenton’s; Natterer’s. The Common Pipistrelle is noticeably the smallest.
- Larger: (up to 8cm): Noctule; Greater Horseshoe.
- Up to 30cm: Common Pipistrelle; Lesser horseshoe; Brown Long-eared; Daubenton’s; Natterer’s. The Common Pipistrelle is noticeably the smallest.
- Greater than 30cm: Noctule; Greater Horseshoe
- The Brown long-eared bat has very large ears that meet in the middle.
- The other species named above have smaller, separated ears.
- If it is flying within 20cm from the surface of water, it is probably a Daubenton’s. However, Greater Horseshoes are sometimes seen flying low over water.
- All of the other species will be found around trees and fields.
- The one most likely to be found in urban areas is Britain’s most common bat, the Common Pipistrelle.
- Brown long-eared bats often pluck their prey from vegetation or the ground.
- Pipistrelles fly very erratically.
- Natterer’s bats can be seen to fly quite close to the ground.
For a bit more information, see this bat identification key.
Finally, to make us all feel better, even the experts use bat detectors. These are machines on which we set the frequency of the ultrasonic emissions we wish to detect. Each bat species emits ultrasonic sounds of a different range, so if we hear no clicks on the range of the species we suspect it is, we change the frequency detector to identify it as a different species.
Photographs: Dodoni (Wikipedia Commons), Lesser Horseshoe; M. Jullion (Greater Horseshoe); G. Gerding (Daubenton’s); Mnolf (Wikipedia Commons), (Common Noctule and Brown Long-eared); Barracuda 1983 (Wikipedia Commons), (Pipistrelle).
Posted on June 12, 2009 - by Denise
The common pipistrelle is the most common species of bat in Britain. This is also the case in Devon. They are the smallest bats, so can be quite easily identified. They have red-brown to darker brown coats; their body is between 35-45mm long and they have a wingspan of 19-25cm. They weigh only between 3 and 8 grammes. Commonly found near water, they can be recognised by their random, jerky, flight, usually below 10m. There are other species of Pipistrelle in Britain, the Soprano pipistrelle and the Nathusius’ pipistrelle. In case, you have a bat detector, the frequency of the common pipistrelle’s echolocation calls is at around 45kHz.
It is worth noting here that all bat species are protected in the UK, so a special licence is needed to be able to handle them.
Best places to see them in Devon:
Pipistrelles can be found in lots of Devon woodlands, especially those in South Devon. They have been seen to come out of caves at Berry Head in large numbers. But really, they can be found anywhere not windy; they feed over water and meadows.
Best time of year to see them:
Between April and September, when they are out of hibernation. They usually start to emerge 20 minutes after sunset. They will occasionally be seen during the winter as they will wake in warm spells and fly out in search of insects.
Woodland, farmland, urban areas, especially around water. They roost and hibernate colonially in caves, trees and lofts or walls of old farm buildings. They can even roost in the eaves of the rooves of modern houses. They just need a centimetre gap to get in.
Flying insects , such as moths, midges and lacewings. They will typically eat around 3,000 per night.
Pipistrelles mate in the autumn. The female can then store viable sperm over the winter so the eggs are fertilised in early spring. One, or occasionally two bat pups will be born in May-August, in a maternity roost, which may contain over a thousand females. They will cling onto the female’s teat for approximately two weeks, and then she will hang it up in a safe place by its feet. The bat pups make their first flight within three weeks and will start to forage for themselves at around 6 weeks.
Threats to their population:
These bats are affected by the chemical treatment of roof and floor timbers, from which they will hang when resting. These chemicals can get through their skin, especially the thin membrane of their wings, and accumulate in their bodies, sadly often killing them.
Wild about Devon spotting:
The Devon Wildlife Trust Nature Reserve ‘Dart Valley’, starting at the New Bridge car park on Dartmoor, 27th June 2009, 10.30pm.
Photograph: Barracuda 1983 (Wikipedia Commons)