Farmland Butterfly Initiative
Target species information – HLS options and Indicators of Success
Heath Fritillary – Feature description
s41 Priority Species. Occurs in three main habitats: sheltered heathland combes on Exmoor (up to 200m400m above sea level) where Common Cow-wheat Melampyrum pratense grows as scattered plants on
mineral soils amongst vegetation dominated by Bilberry. Coppice or newly felled woodland on acid soils.
On a few sites in SW England the butterfly breeds on unimproved grassland with abundant Ribwort
Plantain Plantago lanceolata growing in short or sparse swards on stony soils.
Relevant HLS Options
HK06
Maintenance of species-rich, semi-natural grassland
HK07
Restoration of species-rich, semi-natural grassland
HC15
Maintenance of successional areas and scrub
HC16
Restoration of successional areas and scrub
HK15
Maintenance of grassland for target features
HK16
Restoration of grassland for target features
HR01
Supplement for cattle grazing
HC07
Maintenance of woodland
Other relevant options will be HL9/HL10 Maintenance and Restoration of moorland and HO1/HO2
Maintenance and Restoration of lowland heathland depending on the altitude of the site in question. For
specific areas of Heath Fritillary breeding habitat or where restoring areas, the following prescriptions could
be applied to ensure management is targeted for the species.
Prescription guidance for HK06/HK07
Graze lightly with [cattle and/or hardy ponies] in years [1 to 10, in particular during late winter/early spring
and summer] to maintain the bracken and grassland mosaic and achieve the indicators. Avoid heavy
poaching by managing stock carefully when ground conditions are wet.
In year [1 to 5], follow a programme (agreed in writing with your NE adviser) of rotational Bracken
management through [cutting / bruising / spraying] of [dense Bracken stands following burning
management of gorse to restore bilberry/cow-wheat areas]. Never manage more than [35%] of the site in
any one year.
In year [1 to 5], follow a programme (agreed in writing with your NE adviser) of rotational scrub
management. Never manage more than [35%] of the site in any one year and never completely eradicate
scrub from the site.
Indicators of Success for HK06/HK07
[By year X] shallow (<15cm deep) bracken litter should extend over at least [5% but no more than 15%
scattered] of the total area.
[By year 2] one or more of species [bugle, daisy, tormentil, bramble, common cow-wheat or other popular
nectar plants] should be in flower during May and June, and at least [occasional] across the target area.
The extent of the [Heath Fritillary breeding area, xha] of interest within the [grassland / scrub / successional
area / mosaic / XXXX] as identified [in the Farm Environment Plan / Management Plan / during the Natural
England visit] should be maintained or increased.
[By year XX], at least [2 high-value indicator species Common Cow-wheat and Bilberry for BAP grassland
habitat XXXX should be frequent and 2 occasional] in the sward.
In all years, populations of [Heath Fritillary] should be maintained.
[By year XX], cover of wildflowers in the sward (excluding undesirable species but including rushes and
sedges), should be between [20% and 90%]. At least [40%] of wild flowers should be flowering during
[May-July].
[By year 2 / 5], cover of invasive trees and shrubs [Sycamore / Blackthorn / Cotoneaster / European Gorse]
[but excluding Bog Myrtle / Juniper / Creeping Willow / Bilberry] should be less than [25% with a minimum
of 10%].
[By year 2], species [Common Cow-wheat and Bilberry should be frequent].
[By year 2], cover of [species Common Cow-wheat and Bilberry between 30% and 100%].
Prescription guidance for HC15/HC16
Graze lightly with [cattle and/or hardy ponies] in years [1 to 10, in particular during late winter/early spring
and summer] to maintain the bracken and grassland mosaic and achieve the indicators. Avoid heavy
poaching by managing stock carefully when ground conditions are wet.
In year [1 to 5], follow a programme (agreed in writing with your NE adviser) of rotational Bracken
management through [cutting / bruising / spraying] of [dense Bracken stands following burning
management of gorse to restore bilberry/cow-wheat areas]. Never manage more than [35%] of the site in
any one year.
In year [1 to 5], follow a programme (agreed in writing with your NE adviser) of rotational scrub
management. Never manage more than [35%] of the site in any one year and never completely eradicate
scrub from the site.
Indicators of Success for HC15/HC16
[By year X] shallow (<15cm deep) bracken litter should extend over at least [5% but no more than 15%
scattered] of the total area.
[By year 2] one or more of species [bugle, daisy, tormentil, bramble, common cow-wheat or other popular
nectar plants] should be in flower during May and June, and at least [occasional] across the target area.
[By year XX], the following desirable species [Bilberry and Common Cow-wheat] should be [frequent].
[By year XX], cover of shrub species [Juniper / Box / Hawthorn / Blackthorn / XXXX] should be between
[10% and 25%] of the area. The vegetation within [1m] of the edge of the scrub should be taller than 30cm.
Prescription guidance for HK15/HK16
[From year 2 onwards,] manage the sward by [grazing and/or cutting] to achieve a sward height of between
[5 and 25cm within the breeding area] during [April to June]. [Do not exceed a stocking density of 0.2 LU
per ha for a six week period between 1st May and 31st July, cattle and/or pony grazing between October
and March is preferred, no more than light grazing by cattle/sheep/ponies in other months]
Graze lightly with [cattle and/or hardy ponies] in years [1 to 10, in particular during late winter/early spring
and summer] to maintain the bracken and grassland mosaic and achieve the indicators. Avoid heavy
poaching by managing stock carefully when ground conditions are wet.
In year [1 to 5], follow a programme (agreed in writing with your NE adviser) of rotational Bracken
management through [cutting / bruising / spraying] of [dense Bracken stands following burning
management of gorse to restore bilberry/cow-wheat areas]. Never manage more than [35%] of the site in
any one year.
In year [1 to 5], follow a programme (agreed in writing with your NE adviser) of rotational scrub
management. Never manage more than [35%] of the site in any one year and never completely eradicate
scrub from the site.
Indicators of Success for HK15/HK16
[By year XX], at least [2 high-value indicator species Common Cow-wheat and Bilberry for BAP grassland
habitat XXXX should be frequent and 2 occasional] in the sward.
[By year 2], species [Common Cow-wheat and Bilberry should be frequent].
[By year 2 / 5], cover of invasive trees and shrubs [Sycamore / Blackthorn / Cotoneaster / European Gorse]
[but excluding Bog Myrtle / Juniper / Creeping Willow / Bilberry] should be less than [25% with a minimum
of 10%].
In all years, populations of [Heath Fritillary] should be maintained.
[By year 2] one or more of species [bugle, daisy, tormentil, bramble, common cow-wheat or other popular
nectar plants] should be in flower during May and June, and at least [occasional] across the target area.
Prescription guidance for HR01
Cattle will be the [main] grazing species [during the year, between October and March is prefereed, no
more than light grazing by cattle/sheep/ponies in other months. Annual grazing is recommended at low
stocking densisties]. They will comprise [at least 70%] of the livestock unit grazing days on the parcel.
Prescription guidance for HC07
Maintain open features, including rides and glades.
Indicators of Success for HC07
A network of rides and open ground should cover between [10% and 30%] of the area
Further Information
The Heath Fritillary occurs in a few specialized habitats either woodland clearings with Common Cowwheat, sheltered heathland combes on Exmoor, or flower-rich grassland with Ribwort Plantain. It flies from
May until late June in Cornwall but somewhat later (from late May to July) on Exmoor and in south-east
England. In the south-east there is often a second generation in hot years during August and early
September. The butterfly is now one of our rarest butterflies found only in fewer than 50 colonies in Kent,
Essex and south-west England.
The species uses sunny, warm, and sheltered habitats of three main types: 1) coppiced or newly felled
woodland on acid soils where Common Cow-wheat is abundant; 2) sheltered heathland combes (valleys)
on Exmoor (up to 200–400 m above sea level) where Common Cow-wheat grows as scattered plants on
mineral soils amongst vegetation dominated by Bilberry; 3) on a few sites in south-west England it also
breeds on unimproved grassland with abundant Ribwort Plantain and Common Cow-wheat.
The eggs are typically laid in large batches of up to 150, though sometimes as few as 15. They are
deposited close to the ground on the underside of a leaf immediately next to the foodplant, and only rarely
on the foodplant itself. The larvae feed gregariously in a small, inconspicuous web, but soon disperse into
smaller groups. These groups overwinter during their third instar close to the ground, usually in the leaf
litter where they form a hibernaculum by spinning together the edges of a dead, tightly rolled leaf. The
larvae emerge again in the first warm, sunny days of March or April and feed sporadically in between
lengthy bouts of basking on dead leaves or twigs. They pupate within the leaf litter, often within dead
leaves.
This species is highly sedentary and forms compact colonies but individuals can occasionally disperse up
to 2 km. As many of its habitats are ephemeral, the butterfly has to move regularly to locate new breeding
areas. Despite this nomadic lifestyle, it has very limited colonizing ability and studies in south-east England
have shown that suitable habitats more than 600 m from a population are colonized only slowly, if at all.
Sheltered Heathland Combes (Exmoor)
Aim to maintain short heathy vegetation with scattered Common Cow-wheat growing amongst Bilberry.
Burning
The Heath Fritillary can thrive in immediate post-burn vegetation, providing that colonies survive nearby to
re-colonise. Burning on rotation during winter can thus be highly beneficial to restore short vegetation on
sites that have become too tall or too Bracken dominated to be suitable (e.g. as a result of low grazing
pressure). Some periodic burning may also be essential to maintain habitat suitability under all grazing
systems. Any burning undertaken must be in line with 'The Heather and Grass burning Code'. Wherever
possible, burn before the bird nesting season in March and burn only a part of the breeding habitat in any
single year and allow to regenerate before burning adjacent patches. Ideal burning frequency for each
habitat patch is probably once every 10-15 years (e.g. one-fifth of the area every 2-3 years). Burning is best
followed by Bracken control in the same year (see below) as this plant is invigorated by burning.
Grazing
Grazing should be extensive and spread through the year if possible either by sheep, cattle, or ponies.
Some winter grazing may be preferable to provide some disturbance and shorter vegetation in spring when
Common Cow-wheat germinates. Ideal grazing levels will depend on the pattern and timing of grazing as
well as density. Grazing probably needs to be combined with periodic burning.
Bracken
Many good sites have a light cover of Bracken, though it is not clear how important this is in providing
suitable breeding habitat and in sustaining the larval foodplant. Dense to moderate densities of Bracken
can be suppressed by appropriately timed cutting or rolling (e.g. with a Bracken bruiser), or by encouraging
localised grazing. Bracken monitoring and control may be crucial after burning and is best carried out
during mid July and early August.
Grasslands (Cornwall and Devon)
Aim to maintain herb-rich grassland, with abundant Common cow-wheat and Ribwort Plantain growing in
short/medium vegetation (i.e. 5 - 15cm) usually on stony substrates.
Cutting/mowing
The following two regimes have successfully provided suitable habitat:
1 Cutting every other year during autumn or winter with brush cutters so that half the habitat is cut each
year, and raking cut material.
2 Annual mowing in autumn with tractordrawn 'bush-hog' cutter. Sites may need periodic ground
disturbance to encourage high Plantain densities, so occasional more severe cutting or scraping may be
necessary.
Woodland (Kent and Essex)
Aim to ensure a succession of sunny clearings through coppicing and ride widening with abundant
Common Cow-wheat in otherwise sparse vegetation. Wide sunny rides are needed for the species to move
to new, freshly cleared areas. Coppice small plots (0.4 -2ha) on a rotation of 10-20 years, preferably cutting
adjacent plots within 3 years, or within 300m of an existing colony.
A Factsheet (with ideal habitat management photographs) is available from Butterfly Conservation’s
website which can be given to landowners.