Vale of Glamorgan Council
Cyngor Bro Morgannwg
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High Brown Fritilaries

High Brown Fritilary

The high brown fritillary (Argynnis adippe) is a large butterfly seen flying powerfully over the tops of bracken covered slopes and low vegetation in woodland clearings.

 

In flight the males are very similar to dark green fritillary, which are often found in the same habitat. When feeding from flowers the species can be told apart by distinctive underwing markings.

  

The high brown fritillary has seen a large decline in range (up to 94%) and in 1995 only 51 colonies existed in the whole of the UK. Due to this significant decline it is now classified as vulnerable in the UK Red Data Book.

 

It breeds in two main habitat types: bracken stands where larval foodplants (violets) grow and woodland clearings on limestone outcrop. The latter is believed to be restricted to the Lake District, and all known Welsh sites are bracken covered slopes with:

  • Dense bracken stands where the ground is littered with dead bracken along with sparse grass cover
  • The Common Dog Violet amongst sparse ground vegetation
  • A sheltered, usually south-facing, open and sunny site below 300m altitude
  • A minimum area of 2 to 5 hectares of suitable habitat to support a breeding colony

 

Butterfly - high brown fritilary

The Alun Valley Project

The Alun Valley in the Vale of Glamorgan supports what is thought to be the last population in Wales of the high brown fritillary. Two other species of fritillary are also found there: dark green and small pearl-bordered.

 

In 1999 the population of the high brown fritillary in the Alun Valley had declined to a dangerous low. 

 

In 2003, Butterfly Conservation applied for funding from the Aggregates Levy Sustainability Fund on behalf of the Vale Biodiversity Partnership to undertake a habitat management and restoration programme.

 

With the help of the Glamorgan Heritage Coast project and a dedicated team of volunteers, scrub clearance and coppicing has taken place every winter since 2003 to try to restore breeding habitat.

 

Since the work began, the high brown fritillary has undergone population increases each year and has appeared on all the managed patches. In May 2006, habitat quality assessment was carried out to give a “before and after” comparison which showed that:

  • The coverage of violets (the larval food plant) had increased
  • Bracken litter, grass/moss and sward height had all improved
  • Both high brown fritillary and dark green fritillary were breeding on the site as caterpillars were found
    Annual transect counts of adult butterflies have shown that the population has made a dramatic recovery.