Conserving the Marsh Fritillary in Dorset

The case study of the Marsh Fritillary in Dorset presents an example of a threatened species responding positively to agri-environment schemes used at a landscape-scale.

In Dorset the host plant, Devil’s-bit Scabious Succisa pratensis grows in two contrasting habitats, damp meadows on heavy soils and on dry chalk downland.  The occurrence of the species on chalk grassland is a more recent event as many wet grassland sites disappeared through drainage and agricultural improvement, whilst grazing pressure was reduced on downland allowing the host plant to grow in more favourable sward heights.

Despite the more recent use of chalk downland sites, the abundance of the species has been in decline due to habitat loss and fragmentation. To achieve long-term population stability the butterfly requires an extensive network of well-connected habitat patches where Devil’s-bit Scabious is abundant.

Project Aim

The project aim was to work with Natural England to improve delivery for Marsh Fritillary through agri-environment schemes on the chalk downland sites in Dorset.

Methods

• Butterfly Conservation worked with Natural England undertaking training and land manager advisory visits to explain the ecology and management requirements for Marsh Fritillary.

• In 1998 following advice from Butterfly Conservation a special extensive grazing supplement was introduced to the South Wessex Downs Environmentally Sensitive Area (ESA). 

• Suitable habitat for Marsh Fritillary is best maintained through extensive cattle grazing and consists of a varied sward (average height of 5-12 cm on chalk grassland sites and 12-25 cm on damp grassland sites) with an abundance of the host plant.

• The supplement was to help conserve Marsh Fritillary and other invertebrates known to benefit from extensive cattle grazing rather than sheep grazing (for more detailed habitat requirements and management advice for Marsh Fritillary see the species factsheet).

• Since the introduction of agri-environment schemes Butterfly Conservation worked closely with staff to ensure that key sites are entered into an agreement which maintains or restores the grassland into suitable habitat for Marsh Fritillary.

• Marsh Fritillary status and distribution data has been collected since the 1980s, analysis of the population data, site management and agri-environment schemes assessed the success of the schemes.

Results

• Of the 34 occupied sites between 2001 and 2010, 30 were in a current agri-environment scheme.

• Since a low point (from 1991-95) and the introduction of the extensive grazing supplement, the total number of colonies has risen to the largest number for 30 years, including a higher proportion of larger more stable colonies.

• 97% of downland sites under the ESA showed improved habitat condition and 65% showed a positive species response.

• Data from the UKBMS (UK Butterfly Monitoring Scheme) shows that Marsh Fritillary in Dorset is increasing in comparison with the rest of the UK, especially over the last 10 years.

• Management aimed at maintaining and restoring sites for Marsh Fritillary is also suitable for a wide range of other threatened species utilising the same habitat and foodplant (including Narrow-bordered Bee Hawk Moth).

Success! 

The most crucial element to the successful conservation of the Marsh Fritillary across Dorset has been the targeted advice and long-term support to landowners by Natural England and Butterfly Conservation.  The dynamic nature of Marsh Fritillary means that its long-term conservation requires landscape-scale management of the entire network of existing and potential sites; this includes small sites which can act as stepping stones and that may be critical if core populations decline. Greater efforts are needed to introduce extensive cattle grazing regimes on damp grassland, but more are being grazed for the first time in years.

Funders

Natural England as part of the Species Recovery Programme and Butterfly Conservation Members and Donors.

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