Pearl-bordered fritillary (Boloria euphrosyne)

The pearl-bordered fritillary is found in dry, sheltered open areas, either in clearings between trees or on woodland edges. These habitat patches include young tree plantations, coppiced woodland, rides and corridors along pylon lines where the vegetation comprise a mosaic of bracken amongst mainly acidic grasses and spring woodland herbs such as bugle (Ajuga reptans), the butterfly’s main nectar source. The main larval food plant is the common dog violet (Viola riviniana), although in Scotland the marsh violet (Viola palustris) is sometimes utilised. Marking studies have demonstrated that the pearl-bordered fritillary has low mobility, with the majority of individuals dispersing less than 1 km during their lifetime. The pearl-bordered fritillary is widespread from Western Europe to Asia, although it is in decline in most countries where there are reliable records. It was widespread throughout much of Britain, but it is now extinct over large parts of its former range. It remains abundant at localities in northwest England and the glens of central-northern Scotland (Highland, Argyll, Perthshire, Aberdeenshire and Moray).

Threats

The main threats are loss of clearings and canopy gaps, cessation of grazing on unimproved grassland and abandonment of traditional bracken and gorse management. Open woodland sites that have been targeted for woodland improvement schemes may be threatened in the long-term. Schemes involving deer culling, fencing to exclude stock and deer, or bracken spraying are causes for concern because they may lead to loss of open areas in woodlands. Improved pastures, abandonment of grazing or overgrazing by sheep are also potential threats to the habitat.

Actions for the conservation of the pearl-bordered fritillary

Grass/bracken/scrub habitats: Extensive grazing to promote trampling, in particular during winter and early spring (February to April), aiming to maintain a mosaic of bracken interspersed with grassy patches and gaps, with food plants growing through the litter.

Woodland: maintain flower-rich, sunny clearings with dry vegetation and abundant litter to reduce natural regeneration. Bracken litter and other dead plants are important to provide places for hibernation. Woodland improvement schemes need include grazed open areas with a bracken/grass/herb cover.

More information

UK Butterflies