Night hunter

The county’s bats and projects to pro­tect them

Hertfordshire Life - - CONTENTS -

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 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

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