Bats have been found making themselves at home and settling nicely into a specially built house alongside the new A30 dual carriageway in Cornwall.

As part of National Highways’ A30 Chiverton to Carland Cross upgrade, and among a number of environmental mitigation measures, the bespoke bat house was constructed close to the new dual carriageway early in 2022.

Following extensive survey work and planning with Cornwall Environmental Consultants Ltd, Costain constructed the insulated house incorporating specially designed crevices and open flying spaces to accommodate the needs of varying bat species.

Two years on and the teams have now discovered Lesser horseshoe bats roosting in their new home – constructed of locally sourced Cornish stone and slate – along with recorded activity of brown long-eared and common pipistrelle and myotis bat species.

Earlier survey work ahead of construction identified potential disruption to bat commuting routes and habitats across and alongside the A30, and along with a number of bat and bird boxes installed along the 8.7-mile section of road, the new building is providing a valuable roosting site to protect and preserve the various bat species.

The supply of bat tubes was initially impacted by Covid restrictions, but working with Perranporth company Green & Blue, the CEC team were able to source bat and bird boxes and tubes for the bat barn made from local China clay waste materials.

The new route has been carefully planned and designed to protect the ecology of the area and as part of that work, a total of 33 multi-species crossing points have been constructed to assist the habitats and journeys of animals such as bats, otters, badgers and reptiles.

The success of the bat roosting has been welcomed by the team and as part of the licence conditions, monitoring of all ecology measures, including the bat barn, will continue until 2032.

Jordan Fortune, National Highways project manager for the A30 Chiverton to Carland Cross scheme, said: “We’re proud of the work we’ve undertaken to protect and enhance the ecology and environment in the area, including the bat mitigation, wildlife-proof fencing, Cornish hedging and heathland relocating, and we’re currently forecasting a net gain of over 20% in biodiversity.

“The scheme has been carried out in the most sympathetic way for wildlife and the environment, National Highways has also funded a number of environmental projects around the location of the scheme and this is something we’re also proud to be involved with and which will leave a real legacy for Cornwall.”

Tara McCracken, safety, health and environment manager for Costain, said: “A lot of care was taken before and during construction as part of a collaborative effort across the A30 scheme.

“We have a responsibility to ensure that we are leaving a positive legacy and delivering ecological and environmental benefits above and beyond what is required to complete a project.

“The bat roosting discovery is particularly promising, and the aim for us now is to protect and preserve the bat populations native to the local area. Monitoring will continue via detectors around the bat house and future crossing point surveys.” 

And Steve Marshall, principal bat ecologist at CEC, said: “We were delighted to see evidence of bats moving into the bat house last year, and even more pleased this year to record four species of bats, including Lesser Horseshoes, roosting for the first time.

“Bats can be difficult to mitigate for and typically take more time to colonise new roost sites, but they obviously feel comfortable using this one, and we know there are fairly healthy populations of this species in this part of Cornwall.

“We’ve noticed during our monitoring visits that existing bat roosts and activity along the corridor generally increased during 2024 when compared to 2023 and 2022, which reflects that the scheme corridor is starting to revegetate now the main dual carriageway is operational.”

Since the new dual carriageway opened in June, the wider scheme is continuing with ancillary and finishing-up works throughout the year, including local authority road refinements, landscaping, planting, Cornish hedging and other environmental and ecological work.

Along with footpaths, cycleways and bridleways, work is also continuing on the north side of the Marazanvose green bridge, with planting and landscaping on the bridge through the autumn and winter.

The bulk of the scheme is anticipated to be completed by the end of the calendar year and National Highways will ultimately hand the old A30, which will remain as a local route, to Cornwall Council next year. 

For more information, visit National Highways’ A30 Chiverton to Carland Cross web page.