The fritillary butterflies of Cornwall
Many thanks to Lee Slaughter for his account of Cornwall's fritillaries. Such was Lee's enthusiasm that his original text extended to more than twice as much as we could fit into Wild Cornwall. If you would like a copy of the full article, covering all of the Cornish species, please ask HQ.
We are fortunate here in Cornwall in having approximately two thirds of Britain's butterfly species regularly breeding in our county. Seven of these are "fritillaries", which are usually distinguishable from other butterfly species by their orange coloration on the upper wing, with black/brown patterning, so making a sighting of a "fritillary" species unmistakable. Unfortunately, most of the fritillary species are under great threat due to loss of habitat, failure to continue traditional coppicing of woodlands, drainage of habitat, lack of suitable grazing, or the general tidying up of the countryside.
There is only one species of fritillary not found in Cornwall: the Glanville fritillary, which is restricted to the Isle of Wight. Ours are the pearl-bordered, small pearl-bordered, high brown, dark green, silver-washed, marsh and heath. We will focus on the last two in this article, as they are particularly relevant to two of the Trust's reserves.
The marsh fritillary is a rapidly declining species, not just in Cornwall but across Europe, and the south west of England is one of its last strongholds on a European scale. The main problem is the destruction or deterioration of habitat. The food plant is devil's-bit scabious, which needs to grow in grass no shorter than 6cm and no longer than 15cm as a rule. Total absence of any grazing usually results in the habitat becoming too overgrown, leading to encroachment of scrub.
A good example of this is Breney Common, which had a huge colony of several thousand adults in the early 1980s which declined upon cessation of grazing. It nosedived steeply during the early 1990s and would have become extinct before the turn of this century if the recent efforts in erecting 2.5 tonnes of fencing, clearing of gorse and scrub, and reintroducing grazing by ponies had not been implemented. The species was widespread across Cornwall until recently, but is now much rarer and most colonies without any grazing or management of some kind will die out in due course. The adult butterfly is easy to observe and can be closely approached. It can be seen from late May until late June. It nectars on thistles, ragged robin and several low-growing flowers, but spends much of its time simply basking on dead vegetation. There are, most probably, undiscovered colonies in the wilder, more remote parts of Cornwall, such as Bodmin Moor and the Culm grasslands of North Cornwall. It is now fully protected by law
The heath fritillary almost became extinct in 1980, nationally as well as locally, but happily it was bought back from the point of extinction and now still thrives at Luckett and a nearby locality. Habitat destruction, conifer planting and lack of regular and correct management are the reasons for extinction. The butterfly is very exacting in its requirements, and in the woodland colonies it needs regular coppicing on a five-year cycle. The grassland colonies need careful management too, with any scrub regularly cut or removed and the grass generally cut for hay later in summer and grazed by deer. It is certainly very numerous where it occurs, and is fond of basking in the sun. It is not a strong flyer and is easily photo-graphed. The eggs are laid in batches of about 150 on the underside of ribwort plantain or cow-wheat during June. The adult may be seen from the last week of May until 25th June in most years.
Cornwall Butterfly Conservation is drawing up management plans for each of the fritillary species and is eager to hear from anyone who may record any of the above species away from a well-known colony.Details of how to join Butterfly Conservation and the Cornwall regional branch may be obtained by sending an SAE to Steve Bassett, 36 Rectory Road, St Stephen, St Austell, PL26 7RJ.
Lee Slaughter A founder member and now Chairman of Cornwall Butterfly Conservation, Lee inherited his father's interest in butterflies. When not arranging events, surveys and tasks for the group, he works as an insurance broker for his family's business in St Austell.
Heath fritillary butterflies near Luckett - back from the brink of extinction. Photo: Lee Slaughter