Each year an ‘army’ of enthusiastic BBOWT volunteers carry out weekly butterfly surveys of specific transects (a fixed route walk) on our nature reserves. These transects are part of the UK Butterfly Monitoring Scheme and the data collected has contributed to The State of the UK Butterflies 2015 report.
This year the 55 volunteer surveyors walked 44 transects every week from the beginning of April to the end of September on BBOWT nature reserves. The data collected not only significantly contributes towards the national monitoring scheme but also allows BBOWT to assess butterfly population trends on its reserves and plan the most appropriate habitat management work.
This year our new nature reserve, Yoesden near Bledlow Ridge in Bucks, was surveyed for the first time and 28 species were recorded including three scarce blue species: Adonis, chalkhill and small blue butterflies. If we are able to extend the nature reserve there will be more habitats for these and many other species including grizzled and dingy skipper butterflies.
Targeted and intensive conservation work by the Berkshire team and volunteers at Wildmoor Heath, our heathland nature reserve in east Berkshire is benefitting the elusive silver-studded blue butterfly.
Cutting some of the heather very low creates the perfect habitat for the butterfly to lay its eggs. Bare soil is ideal for the two species of black ant that tend the larvae when it emerges, and look after it within the ant-hill until the butterfly emerges in July. Adult silver-studded blue butterflies feed and roost on taller mature heather and gorse. We continue to manage the reserve on a rotation cycle to create the right combination of height and diversity of habitats to meet the butterfly’s life cycle.
Four butterflies were recorded on any one survey visit in 2011 and, since the habitat management work has been carried out, the numbers have increased: a maximum of 15 were counted there in one day in 2015.
The silver-washed fritillary butterfly has also shown an increase in numbers on our woodland reserves where teams of volunteers and staff have coppiced trees and cut back scrub to create open flower-rich, sunny rides and glades which are favourite habitats for these large orange and brown coloured butterflies.