Restoring Marsh Fritillary metapopulations on Dartmoor

Marsh Frit

The Marsh Fritillary Euphydryas aurinia is one of the fastest declining species in England, recorded as losing 66% of its colonies in England between 1990 and 2000.

The Marsh Fritillary breeds in open grassy habitats, especially damp grassland dominated by tussock-forming grasses; calcareous grassland (usually on west or south-facing slopes) and heath and mire vegetation. Devil’s-bit Scabious Succisa pratensis is the larval foodplant.

The wet grasslands or Rhôs pastures of Dartmoor are recognised as one of the Marsh Fritillary’s UK strongholds but even here they have been affected by the loss of unimproved grassland, mainly due to agricultural improvement and changes in land management.

On Dartmoor, lack of grazing is a common problem. Under-grazed, neglected or abandoned habitat patches quickly become unsuitable for the butterfly, as European Gorse Ulex europaeus, Western Gorse Ulex galli and willow Salix spp. scrub dominate and the grass sward becomes rank and overgrown, shading out foodplants.As habitat loses condition through lack of management, connectivity within the landscape is reduced, leaving the remaining patches isolated and their Marsh Fritillary colonies vulnerable.

Project Aim

To reverse the declines of the Marsh Fritillary across Dartmoor by introducing butterfly-friendly management on unoccupied as well as occupied patches to increase the area of potential breeding habitat and improve connectivity between these  patches.

Methods 

  • Scrub control fencing/boundary works undertaken, to enable grazing by hardy cattle or ponies to be re-introduce.
  • Felling of small areas of woodland and cutting of hedges, to create clear flight paths and improve connectivity between habitat patch.
  • Planting of Devil’s-bit Scabious, to improve the quality of breeding habitat.
  • Support given to Natural England staff - assisting in agri-environment applications and ensuring appropriate management prescriptions are included in the agreement terms.
  • Training events organised for conservation professionals, landowners and contractors.
  • Volunteers recruited and organised to undertake practical management and species monitoring.
  • Guided walks and other public events held to increase understanding and appreciation of butterflies. 

Results

Read The Full Report

For more detailed information about this project and others across the UK please read the full report: Landscape-scale Conservation For Butterflies And Moths: Lessons From The UK.

  • Working with landowners and Natural England staff, the project helped to secure Higher Level Stewardship agreements at eight farm holdings on one valley system (on which suitable habitat patches had been identified), supporting appropriate management over a ten year agreement period.
  • Between 2005 and 2010 the area of confirmed occupied habitat in the Fernworthy-Long Lane network rose from 33 ha to 86 ha. The number of  habitat patches occupied by the butterfly tripled and  number of larval webs in this valley increased by 1,082%.
  • Conservation measures taken to help the Marsh Fritillary has helped to maintain and restore habitat on a landscape-scale for other declining Lepidoptera, such as the Narrow-bordered Bee Hawk-moth Hemaris tityus and Small Pearl-bordered Fritillary Boloria selene, as well as a wide range of other flora and fauna found in wet pastures.

Success!

This project demonstrates why agri-environment schemes, such as Environmental Stewardship, are a key mechanism to deliver targeted management across whole landscapes to benefit threatened butterflies and moths. Over £100k in funding was secured through agri-environment scheme agreements and other sources for one valley system, which supported capital expenditure on fencing and scrub control and provided landowners with area-based payments to graze their habitat with low numbers of hardy animals suited to this type of rough grassland at the appropriate time of year.

Funders

This is part of the Two Moors Threatened Butterfly project which is funded by: Natural England, Exmoor National Park Authority, Dartmoor National Park Authority, The Environment Agency, Dartmoor Sustainable Development Fund, Exmoor Sustainable Development Fund, Care Moor for Exmoor, Exmoor Trust, BC Devon Branch, BC Somerset and Bristol Branch.

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