The county’s bats and projects to protect them
Flitting out of the twilight, a dark shape caught with the edge of the eye, bats are as charismatic as they are misunderstood.
Britain is home to 18 species. The largest is the noctule with a wingspan up to 40cm. The smallest, the pipistrelle, has a wingspan of 20cm and weighs as little as 3g – the same as a two pence piece. Despite its size, the pipistrelle is a voracious hunter and can gobble up more than 500 insects an hour.
In Hertfordshire we regularly find 10 of Britain’s bat species, with the most numerous being the common and soprano pipistrelle. You’re in with a good chance of spotting them as they often live in urban areas – roosting under a broken roof tile or a crack in buildings – and fly around gardens and parks in the evening hunting for food.
Herts is home to a more uncommon species of bat – the barbastelle. It is classified as a European Protected Species and is listed as near threatened on the International Union for Conservation of Nature Red List. Barbastelles are also protected in the UK under the Wildlife and Countryside Act and classified as a priority species in the UK Biodiversity Action Plan. Herts and Middlesex Wildlife Trust is committed to their conservation and has identified barbastelles as one of seven priority species in its 2016-2021 strategic plan.
In 2016 the Hertfordshire Barbastelle Bat Project was set up as a partnership between the
trust and Herts and Middlesex Bat Group to increase knowledge of this rare bat’s distribution in Herts. Only one barbastelle maternity colony was known in the county, discovered by the bat group near Bishop’s Stortford in 2012. Following surveys, volunteer training sessions, bat box installation and the radio tagging and tracking of barbastelle, in the summer a second maternity colony was discovered at the National Trust’s Ashridge Estate near Tring. This is an extremely exciting find and will help us protect this species as we learn more.
Barbastelle have very specific roost requirements – peeling bark in ancient woodland. These trees are often dead, dying and damaged, with cracks, splits or peeling pathways – just the sort of tree that is routinely removed for health and safety reasons. With our new findings we can help protect these vital habitats and the wildlife that rely on them.
A rare bat in the UK and a priority species under the Eurobats agreement, very few maternity roosts of Nathusius’ pipistrelle have been recorded in the UK. Until last year only five continentally ringed Nathusius’ pipistrelle had been recovered in the UK. This increased to seven when two of the species, originally ringed in Latvia, were recorded at the trust’s Stocker’s Lake Nature Reserve in Rickmansworth.
The trust is now working with partners on an ambitious project to learn more about this rare and poorly understood bat. The project, made possible by support from High Speed 2 additional mitigation funding, aims to monitor and improve the population of Nathusius’ pipistrelle in the Colne Valley. This will include detailed monitoring of bats at dedicated stations, radio tracking and remote acoustic monitoring. The trust will also help to train volunteers to help with ongoing monitoring of Nathusius’ pipistrelle populations. Data produced by this project will be shared with site managers, local records centres, the
Bat Conservation Trust and international partners to inform our knowledge of the ecology of the species and guide conservation efforts.
This year remote detectors were deployed across key sites and showed good levels of Nathusius’ activity at each one. Stocker’s Lake had the highest number of contacts, with 161 in one night.
With the daylight hours dwindling as we progress into autumn, now is a great time to go out and look for bats. Whether watching them in woodlands or skimming over a river, the sight of a bat quickens the heart. The best time to see bats is just after sunset over lakes and fields or in woodland rides. Go online to hertswildlifetrust.org.uk/events for bat events in your area, where an expert can show you how to use a bat detector to listen for bats echolocating for food.
‘A maternity colony was discovered this summer at Ashridge’
LEFT:A bat detector identifies bats echolocating while huntingFAR LEFT:Rare Nathusius’ pipistrelle – two were recorded at Stocker’s Lake Nature ReserveBELOW:A Daubenton’s bat over water – rivers and lakes after sunset are some of the best places to spot bats