Bracken for butterflies

by James Mann

It has been widely accepted that the

decline of many of our Fritillaries has been as result of changes of woodland management such as abandonment of

coppicing. If these butterflies cannot find

alternative habitats they will die out.

Butterfly Conservation have produced a leaflet 'bracken for butterflies' the opening statement of which is:-The presence of bracken in habitats ranging from open hillside to woodland can be important for many forms of wildlife, bur is especially vital for four highly threatened Fritillary butterflies, the High Brown Fritillary, the Pearl-bordered Fritillary, the Small Pearlbordered Fritillary and the Dark Green Fritillary. For these species, suitable habitats occur in open, sheltered situations often where there are mosaics of grass, bracken and scrub. The bracken fronds act like a woodland canopy for the Violet foodplants and bracken litter provides a warm microclimate for development of the immature stages.

Although we know longer have these Fritillaries in Suffolk and cannot hope for them to return by themselves there is no reason for us not to attempt to identify potentially suitable bracken habitats for Fritillaries. If we find areas of bracken habitat that also support violets it is important to pinpoint the location to enable further investigation and possible

Dark Green Fritillary by Douglas Hammersley

management as these may become suitable sites for reintroduction in the future. The easiest method is to search for key areas in Spring before the bracken fronds have unfurled. Bracken stands which are sheltered and south facing ate those most likely to be suitable for Fritillaries. In Spring, Pearl-bordered Fritillary and High Brown Fritillary bracken habitats are characterised by violets growing through a shallow (under 15cm) bracken litter. Suitable mosaics are typically 1 /3 grass to 2/ 3 bracken. In contrast, Small Pearl-bordered Fritillary bracken habitats may have abundant purple moor-grass or tufted hair grass, with Dark Green Fritillary bracken mosaics frequently consisting of I /3 bracken and 2/3 grass. The Sandlings certainly supported High Brown Fritillaries in some areas until the 1960' s and may well have supported Pearl-bordered Fritillaries. Many of the largest Fritillary colonies occur in managed bracken communities so if we can identify suitable habitats there is no reason for us not to have Fritillaries in Suffolk in the future.