Natural England is reviewing the SSSI designations at Bernwood, Buckinghamshire, home to one of the largest and most northerly colonies of Bechstein’s Bat in the UK. The area is also within the limited UK range of the Black Hairstreak butterfly Satyrium pruni.
Natural England undertook field surveys for the Black Hairstreak butterfly, in woodlands and surrounding land at Bernwood, in 2018 and 2021. The locations of all sightings were noted and other species recorded for reference. During the 2021 survey, weather conditions were less suitable for observing Black Hairstreak but records were noted in a number of locations. The location of good quality supporting habitat was recorded and mapped in the course of both surveys.
To supplement these sightings, additional work was undertaken in 2021 and 2022, to identify the location of suitable supporting habitat for Black Hairstreak. This involved both field survey and interpretation of aerial photography.
Additional information on sightings of Black Hairstreak has been provided by Natural England Field Unit and by Butterfly Conservation members.
This report summarises the results of this compilation of records of sightings and the location of suitable supporting habitat. The work shows that Black Hairstreak is widely distributed in the survey area. There is evidence that several discrete breeding populations are present in the survey area, and that some of the woods support several colonies.
This confirms that collectively the Bernwood complex of woodlands and hedgerows forms an important national stronghold for Black Hairstreak.