Bats in Wanstead

The noctule batThe noctule bat

Ahead of a bat walk in Wanstead Park this month, Bob Vaughan takes a look at our local furry flying creatures, which are difficult to see and impossible to hear without specialist equipment.

Bats go almost unnoticed because they are nocturnal and their calls are outside of the normal human hearing range. This makes them a challenge to see, but with a little knowledge and a suitable bat detector (a piece of equipment that converts bat echolocation 'shouts' into audible sounds), a few of these cryptic species have been found to be common in Wanstead.

The noctule bat (Nyctalus noctula) is one of the larger British bats and can be found in Wanstead Park and out on the Flats at dusk. It nests in and frequents trees. It can sometimes be seen against the bright London skyline as it flies out quite high at 10 to 50 metres with a rapid flight looking to catch insects. With a bat detector, it has a long, low frequency call, around about 20 kHz.

Daubenton's bat (Myotis daubentonii) is a smaller bat and tends to fly low over open water. It is more difficult to see unless it is a moonlit night and you stand by one of the ponds in Wanstead Park and look for its rapid and erratic flight. Using a bat detector, it makes a series of clicks, which when displayed show a high start and plunge to a lower frequency. The clicks accelerate rapidly when it is approaching its insect prey.

The common pipistrelle (Pipistrellus pipistrellus) is probably our most common bat but it is small with very rapid flight close to trees. This makes it hard to see, but with a bat detector, it has calls between 40 and 50 kHz, so when the clicks are heard, look up towards the trees and try to see its rapidly swerving flight against the sky.

There is another, more recently discovered species, soprano pipistrelle (Pipistrellus pygmaeus) with higher frequency calls, but this bat has a rather similar flight and habits to the common pipistrelle, so to distinguish this species requires a well-tuned bat detector.

A rather more elusive species has been recorded in Wanstead Park, the brown long-eared bat (Plecotus auratus). This is a medium-sized bat, associated with trees and with a strategy of taking insects in flight and off the surface of vegetation in fluttering flight. It is not at all easy to see and it is also difficult to detect as it has a quiet call only audible from about five metres with a standard bat detector. It is out there in Wanstead Park but a challenge to find.

A bat walk in Wanstead Park will take place as part of the Wren Wildlife Group's bio-blitz on 23 June from 9pm (meet by the tea hut) – call 07505 482 328

blog comments powered by Disqus