Rare fritillary numbers boost at Devon reserve

A 20 year survey of pearl-bordered and small pearl-bordered fritillary butterflies at Devon Wildlife Trust's (DWT) Marsland nature reserve has revealed that numbers have been increasing dramatically (over 200%) for both species when compared to the overall national decline thanks to careful management.

Gary Pilkington, Nature reserve officer, has been managing the site for over 20 years to improve the wooded valley's glades and pastures for the benefit of these rare butterflies. It is one of the most closely monitored sites in the South West for butterflies and the knowledge accrued over the years has really paid dividends.

5 species of fritillary

The 212 hectare site on the North Devon coast supports five species of fritillaries in total and last year received funding from the North Devon AONB Sustainable Development Fund to further boost numbers. As the flight season comes to an end for the pearl-bordered fritillaries the signs are looking good for another year.

DWT's Gary Pilkington said: "We have worked hard over the last two decades to improve the habitat for these beautiful and rare insects and it is great to see such positive improvements compared to the 50% decline nationally for both the species. Over the years we have learnt exactly what they need to thrive here including appropriate bracken control, scrub management and providing the open ground loved by the pearl-bordered fritillaries. This is the ideal time of the year to see small pearl-bordered fritillaries in flight so our next job this month will be to monitor their numbers."

The management work has been carried out by DWT staff, local contractors and volunteers which have all helped to remove gorse, willow, alder and other scrub in the habitats best suited to the butterflies.

Similar work over the years has seen large increases in the numbers of common dog-violets which is the food plant of the fritillaries', caterpillars as well as bugle which is the main nectar source for the adults.  With each of the species preferring slightly different habitat it has been a balancing act over the years.

Gary added: "The small pearl-bordered fritillary thrives in the damper sections of the woodland, whilst the pearl-bordered fritillary enjoys the sunny west-facing slopes. Even though we are doing well, the work still has to continue each year, it's a constant battle. One of the other fritillaries, the high brown is only just hanging on here so we certainly can't rest on our laurels!"