Priority Species: Dark Green Fritillary
1. Protect and enhance existing populations of the Dark Green Fritillary in the DBAP area
2. Expand the range and size of population of Dark Green Fritillary
3. Maintain and enhance suitable habitat at known occupied sites and potential sites
Vision Statement: To have a better understanding of the species’ distribution in the Durham BAP area
|1. To increase the range of the dark green fritillary in the Durham BAP area.||expand||sites||6|
|2. To increase the population of the dark green fritillary in the Durham BAP area.||expand||no of colonies with more than 100 individuals||1|
The Dark Green Fritillary is the most widespread of Britain’s fritillaries, and occurs in a wide range of flower-rich habitats including grasslands, moorland, wet flushes and heath with bracken. Its food plants are Viola species, most often using Common and Marsh violets (Viola riviniana & V. palustris).
It is a single-brooded butterfly on the wing from early June to late August,. Eggs are laid on the foodplant, or on nearby dead plants or bracken. The larvae overwinter amongst dead grass or litter.
The species is highly mobile and usually occurs at low densities over large areas within which there are small pockets of suitable breeding habitat. However, loss of flower-rich swards in all habitats, through overgrazing or scrub encroachment, will lead to isolation of remaining colonies and probable extinction, even in such a mobile species.
The species appears to be suffering a range decline across eastern Britain. Reasons for the decline are poorly understood. It has been suggested that an increase in sheep grazing of moorland may have affected the abundance of its larval foodplant in Durham.
As recently as 1986 it was described as widespread in the west of County Durham with strongholds at Pikestone Fell, Bollihope Common and Hamsterley Forest. Its current status in Durham is unclear as most records are of singletons. However, the butterfly has been recorded from several new localities, including a few in the east of the Durham BAP area, although it is not known if these represent breeding areas.
- Loss of flower-rich grassland and moorland containing violet species, through overgrazing or agricultural ‘improvement’.
- Isolation of remaining colonies.