One of our rarest butterflies, the heath fritillary is a light orange-brown in colour with dark brown markings; the underside is pale yellow with dark orange markings and a number of white spots (1). The caterpillar grows up to 2.4 centimetres in length, and has a black body with whitish spots, orange spines and a black head with white marks (2).
The adult flight period generally occurs between late May and early July; the heath fritillary can be seen flying close to the ground and taking nectar from bramble flowers, buttercup and ox-eye daisy (5). The species is single-brooded, eggs are laid in large clumps near the ground on the underside of a leaf on a plant next to the foodplant. Larvaehibernate in a tube made from a dead leaf, which is rolled and sealed with silk. They emerge the following spring to complete their development and pupate in leaf litter (1).
Widespread throughout much of Europe, reaching into Asia, this species was once found in many areas of southern England, but it suffered a serious and rapid decline in the twentieth century. In 1980 the heath fritillary was very endangered and just 31 colonies were found in Kent and areas of south-west England. After 1981, new colonies were found in Exmoor, but recent research has shown that the number of colonies on Exmoor declined by 50 percent in the last ten years (4).
Found in well-drained, warm, sunny and sheltered habitats. Three main habitats are utilized and the species has different requirements in each. In coppiced woodlands or woodlands that have been recently felled, the species breeds on common cow-wheat (Melampyrum pratense). On unimproved grassland it feeds on ribwort plantain (Plantago lanceolata) and germander speedwell (Veronica chamaedrys). When the heath fritillary occurs on sheltered heathland, the main host plant is common cow-wheat, but sometimes foxglove (Digitalis purpurea) is utilized. In all habitats, the foodplant must grow in abundance in otherwise sparse vegetation (5).
The heath fritillary has suffered as a result of the decline in coppice management as well as the widespread coniferisation of deciduous woodland. On moorland, a lack of regular burning and suitable grazing regimes has contributed to the decline (5). Further problems arise as populations become increasingly fragmented and isolated (5).
It is likely that the heath fritillary would have become extinct in England if it were not for the huge conservation effort that has been undertaken to save it (6). The ideal management techniques for this species are well understood; woodlands should be coppiced on a rotational basis (5), and clearings should be linked with rides(6). A number of nature reserves in Kent have been managed in this way, which has stimulated large increases in the numbers of this species. The National Trust has also managed heathland habitat in Exmoor in ways that suit the heath fritillary, with sheep and cattle grazing, and a programme of rotational burning of the heath to maintain a short sward. The heath fritillary is a priority species under the UK Biodiversity Action Plan (3).
The UK Biodiversity Action Plan for this species is available at UK BAP.
Coppicing is a traditional form of woodland management in which trees are cut close to the base of the trunk. Re-growth occurs in the form of many thin poles. Coppiced woodlands are cut in this way on rotation, producing a mosaic of different stages of re-growth.
A winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
Stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
The process of forming a pupa, the stage in an insect's development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
The footpaths and access tracks which run through and divide blocks of trees in woodland. Many rides contain a mixture of rich flora and structure, and provide different habitat conditions for a range of wildlife.
Stewart, K.S., Bourn, N., Warren, M. and Brereton, T. (2001) The Heath Fritillary (Mellicta athalia) on Exmoor: Changing Status 1980-2000 and Conservation Recommendations. Butterfly Conservation, Wareham.
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