The Wren Wildlife Group, London Wildlife Trust and Wild Wanstead have compiled a list of 10 species at risk of local extinction. In the last of a series of articles looking at each species in turn, Susie Knox explains why she’s bats about pipistrelles
Pipistrelles are small bats with brown fur and a black face and wings. Their wingspan is about 20cm and they weigh no more than a pound coin. Pipistrelles roost (spend the day) hidden out of sight, singly or in small groups, in crevices in buildings, tree holes and bat boxes. They emerge to feed around 20 minutes after sunset, dining on flies, midges and mosquitoes.
Pipistrelles fly in a fast, jerky way, two to 10 metres above the ground as they pursue small insects, which they catch and eat on the wing. A single bat can consume up to 3,000 insects in one night.
There are two different species of pipistrelle bat in Wanstead: the common pipistrelle and the soprano pipistrelle. Common pipistrelle bats have a slightly lower-pitched voice than their soprano cousins.
Common pipistrelles normally breed in autumn and winter, but will not give birth until the following summer. Males establish courtship territories, which they patrol while emitting high-pitched calls to attract the attention of females. When ready to give birth, females gather in large maternity roosts. Typically, they have one baby (pup), which is fed on its mum’s milk for the first few weeks. The young bats can fly at around three weeks old and by six weeks they are fully independent.
The best time to spot pipistrelles is April to September. They hibernate between December and March, finding a crevice in a building where it’s warm and sheltered.
Pipistrelles are the most common and widespread bats in Britain, but like other species, they’re coming under pressure as land is developed and the wooded areas, ponds and open green spaces they rely on for hunting shrink. It’s unclear how their numbers are holding up. We know from scientific evidence and the absence of bugs on our car windscreens that there have been very significant declines in flying insects, their food source. Another potential threat is the loss of roosting sites due to modern construction and insulation methods reducing the gaps and crevices where bats can shelter.
The Wanstead area is blessed with several lakes surrounded by woodland – ideal places for pipistrelles to hunt at night. Hollow Pond on Leyton Flats and Perch Pond in Wanstead Park are both very good, but there is evidence that numbers there have declined in the last few years.
How to help
- More trees! They’re really important for common pipistrelles. Trees provide cover as bats emerge from their roosts and they often follow treelines to help navigate when out hunting. Plant new trees at the back of your garden and nurture any mature trees you’ve got – they have nooks and crannies where bats can roost.
- Make your garden an oasis for flying insects. Fill it with dense foliage and pollinator-friendly plants like aubretia, jasmine and Michaelmas daisies. Have a wild area with food plants for moths, such as honeysuckle, hawthorn, ivy and sweet rocket.
- Install a wildlife pond and create a long grass area.
- Reduce light pollution by ditching unnecessary night lights in your garden – it disorientates bats and is thought to be contributing to the dramatic decline in insects.
- Put up bat boxes.
- Don’t use pesticides and lobby the council against their use.
For more information about the 10 species under threat of extinction in Wanstead, visit wnstd.com/the10