Bats and licensing: a report on the success of maternity roost compensation measures

Published source details Mackintosh M. (2016) Bats and licensing: a report on the success of maternity roost compensation measures. NatureScot report, no. 928.
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This study is summarised as evidence for the following.

	Action	Category
	Manage microclimate of artificial bat roosts Action Link
	Retain existing bat roosts and access points within developments Action Link
	Legally protect bats during development Action Link
	Legally protect bats during development Action Link
	Create alternative bat roosts within developments Action Link
	Provide bat boxes for roosting bats Action Link

Manage microclimate of artificial bat roosts

A replicated, before-and-after study in 2011–2015 of seven building developments with replacement bat maternity roosts across Scotland, UK (Mackintosh 2016) found that two heated bat boxes were used by individual bats at one of seven sites but in numbers lower than the original roost, and none were used by maternity colonies. At one site, two heated bat boxes installed inside the roof of a building were used by individual common pipistrelle bats Pipistrellus pipistrellus but in lower numbers than the original roost (bat box: 5 bats; original roost: average 14 bats). At six sites, heated bat boxes installed on the exterior of buildings were not used by bats. The original roosts were used by maternity colonies of common pipistrelles (average 5–13 bats) and soprano pipistrelles Pipistrellus pygmaeus (average 36–167 bats). The numbers of bats counted before development were extracted from reports submitted with licence applications. Bats were counted at each roost after development during at least one dusk emergence or dawn re-entry survey in May–September 2015.

(Summarised by: Anna Berthinussen)
Retain existing bat roosts and access points within developments

A replicated, before-and-after study in 2011–2015 of nine bat maternity roosts retained within building developments across Scotland, UK (Mackintosh 2016) found that four of nine retained roosts were used by maternity colonies after development, and two of the roosts were used by greater or similar numbers of bats. Average roost counts before and after development at the four roosts either remained stable (before: 2 brown long-eared bats Plecotus auritus; after: 2 brown long-eared bats), increased by 7% (before: 476 soprano pipistrelles Pipistrellus pygmaeus; after 507 soprano pipistrelles), decreased by 39% (before: 341 soprano pipistrelles; after: 208 soprano pipistrelles), or could not be counted (use inferred from brown long-eared bat droppings only). The other five roosts were not used at all (two brown long-eared bat roosts, two common pipistrelle Pipistrellus pipistrellus roosts) or had signs of use by bats at a later date (one whiskered bat Myotis mystacinus roost). Original roosts were either retained (seven sites) or partially retained (two sites), and original access points were reinstated. The numbers of bats counted before development at each roost were extracted from reports submitted with licence applications. Bats were counted at each roost after development during at least one dusk emergence or dawn re-entry survey between May and September 2015.

(Summarised by: Anna Berthinussen)
Legally protect bats during development

A replicated, before-and-after study in 2011–2015 of 28 bat maternity roosts subject to licenced building developments across Scotland, UK (Mackintosh 2016) found that five of 28 compensation roosts provided were used as maternity roosts by the target bat species after development, and two of the five roosts were used by a similar or greater number of bats as before the development. Average roost counts before and after development at the four roosts either remained stable (before: 2 brown long-eared bats Plecotus auritus; after: 2 brown long-eared bats), increased by 7% (before: 476 soprano pipistrelles Pipistrellus pygmaeus; after 507 soprano pipistrelles), decreased by 39% (before: 341 soprano pipistrelles; after: 208 soprano pipistrelles), or could not be counted (use inferred from brown long-eared bat droppings only). Four of five sites retained the original bat roost and access points within the development, and one site had bat boxes installed (3 x Schwegler design 1FFH) on an external wall near the original roost location. Compensation roosts followed the designs in Species Protection Plans. The numbers of bats counted before development at each roost were extracted from reports submitted with licence applications. Bats were counted at each roost after development during at least one dusk emergence or dawn re-entry survey between May and September 2015.

(Summarised by: Anna Berthinussen)
Legally protect bats during development

A review in 2015 of development licences affecting bats across Scotland, UK (Mackintosh 2016) found that the number of licences issued had increased from 2012 to 2014. Licences issued increased over three years from 80 in 2012 to 180 in 2014. A total of 437 development licences were issued for bats between July 2011 and December 2014, 67 of which related to maternity roost sites. All UK bat species are protected by UK and European law. Licences are therefore issued for certain activities that involve mitigation and/or compensation for the impacts of development. Licensing information collected by the governmental licensing authority, Scottish Natural Heritage, was analysed.

(Summarised by: Anna Berthinussen)
Create alternative bat roosts within developments

A replicated, before-and-after study in 2011–2015 of 19 building developments with alternative bat maternity roosts across Scotland, UK (Mackintosh 2016) found that three bat boxes provided at one site were used by a maternity colony, but bat boxes and lofts at 18 other sites were not used by maternity colonies. At one site, a group of three bat boxes (Schwegler design 1FFH) was used by a maternity colony of soprano pipistrelles Pipistrellus pygmaeus after development, but fewer bats used them than the original roost (average count in original roost: 62 bats; average count in bat boxes after development: 20 bats). Alternative roosts at 18 other sites (16 with heated or unheated bat boxes, two with bat lofts) were not used by maternity colonies, but some (two bat boxes, one bat loft) were used by 2–5 individual bats. Bat boxes were mounted internally or externally on developed buildings, or on nearby trees, either singly or in groups (2–15 bat boxes). Bat lofts were purpose-built structures with internal flight spaces. The numbers of bats counted before development at each roost were extracted from reports submitted with licence applications. Bats were counted at each roost after development during at least one dusk emergence or dawn re-entry survey between May and September 2015.

(Summarised by: Anna Berthinussen)
Provide bat boxes for roosting bats

A replicated, before-and-after study in 2011–2015 of 17 building developments with replacement bat maternity roosts across Scotland, UK (Mackintosh 2016) found that three bat boxes provided at one site were used by a maternity colony, but bat boxes at 16 other sites were not used by maternity colonies. At one site, a group of three unheated bat boxes (Schwegler design 1FFH) was used by a maternity colony of soprano pipistrelles Pipistrellus pygmaeus after development, but fewer bats used them than the original roost (average count in original roost: 62 bats; average count in bat boxes after development: 20 bats). Alternative roosts at 16 other sites with heated (seven sites) or unheated bat boxes (9 sites) were not used by maternity colonies, but bat boxes at two sites (one heated, one unheated) were used by 2–5 individual bats. Bat boxes were mounted internally or externally on developed buildings, or on nearby trees, either singly or in groups (2–15 bat boxes). Bat box design varied at each site. The numbers of bats counted before development at each roost were extracted from reports submitted with licence applications. Bats were counted at each roost after development during at least one dusk emergence or dawn re-entry survey between May and September 2015.

(Summarised by: Anna Berthinussen)