Bat Mitigation – Lesser Horseshoe
In 2018, Quantock Ecology was approached by a client near Bristol in North Somerset, who wanted to convert a redundant milking parlour on site, into a more usable outbuilding for the storage of farm equipment and tools.
The initial Preliminary Roost Assessment (PRA) was undertaken during April and surprisingly, it was recorded as a confirmed lesser horseshoe bat roost. This was surprising, as the structure was an open and exposed block built structure, covered with a corrugated asbestos roof. 
The roof was supported by a thin metal frame and from the outside, appeared to provide very little in the way of suitable roosting features for bats. Most of our bat species are crevice dwelling and as such, prefer gaps and cracks in stonework, under lead flashing or under roof tiles (as a few examples). Certainly from the outside and if it wasn’t for the fact that a number of lesser horseshoe bats were hanging up inside, the structure appeared to provide a pretty low or even negligible habitat value.
Characterising the roost
In line with the National Survey Guidelines, two dusk and one dawn survey was undertaken on site by two Quantock Ecology surveyors during the spring/summer months, at approximately 4 weeks apart. 
The results of the survey concluded that the site was actually a maternity roost for a maximum of 12 lesser horseshoe bats, with young and pups recorded present during the final survey. The bats were noted emerging from a opening above a doorway, and flying around to a small lean to located at the rear of the building to ‘warm up’ before leaving the site to forage.
What happens next?
Planning consent was granted following the completion of the surveys, and an application for a European Protected Species Mitigation Licence (EPSML) was submitted to and approved by Natural England. Mitigation in this instance, included the creation of a dedicated ‘bat loft’, within a neighbouring open barn directly next door to the existing roost. The loft was designed by Simon Pidgeon at Quantock Ecology, who has years of experience in providing mitigation measures for a number of bat species. The internal space was created by boarding the roof area between the tiles and timbers, with the creation of a floor area. The space provides measured approximately 8m in length, 5m in width and approximately 2m from floor to apex. A fly in opening of approximately 300mm by 200mm was cut into the front gable end, to provide internal access for this species of bat.
Lesser Horseshoe Bat Mitigation – Creating a Bat Loft
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n January this year, the works began to the milking parlour, once the bat loft had been created. The roof was removed under ecological supervision and an inspection of the new bat loft was undertaken, to ensure it was fit for purpose.
The loft was constructed towards the tail end of 2018 and had been in place for several months. Upon inspection, it was evident that lesser horseshoe bats had already started using the structure. A number of lesser horseshoe droppings were noted towards the end of the loft area, suggesting that bats had already began to investigate their new home, even before their original one had been removed. This was a great result for not only the bats, but also the landowner who was very keen to ensure that bats were adequately mitigated for during the project. Further surveys next year (a condition of the licence), will confirm the new roost is being used by a maternity colony and suggest any minor adjustments which maybe required.
Lesser horseshoe bats are an uncommon species, confined to the southwest, South Wales and parts of southern England. They are very faithful to their roosts and sensitive to any (new/introduced) lighting, which can fragment commuting routes or cause bats to abandon roosts if directed to emergence points.
If you would like to find out more about mitigation measures for bats, or need to apply for a mitigation licence, please get in touch.