Rogerdodge wrote:
Dartmoor and Exmoor do not currently have the required habitat in any sort of density.
The High Moorland blanket bogs on Dartmoor have a very high density of Hare's Tail Cottongrass, together with Cross-Leaved Heath. The habitat may well be suitable for Large Heath, if a little exposed.
Dear Rogerdodge,
You are right and I am wrong. There are goodly amounts of data which suggests Dartmoor is very interesting for Large Heath. There are, however, two facets which perhaps you might not be acquainted. Old records for Dartmoor do exist and I possess the largest private database of botanical information for the area in question.
Records per Harry T. Eales, c.1998, work: - “
Sites in England and Wales from which the Large Heath Butterfly, C. Tullia. Müller. has been recorded since its discovery as a British species in 1795.”, include: - SX5073, Hares Down Moor, date unknown, via
NCC files, Tavistock, ISR. Considered by Harry to be a confusion in place names between the nearby Whitchurch and the one where the butterfly still occurs in Shropshire. I’m not so sure. And: - SX59, (near) Okehampton, pre 1876,
H. Rowland-Brown, Etudes de Lepidopterologie compree. (1912) 7: 115-6. Bizarrely, this is what Harry has to say on this latter record: - “In view of the doubts cast upon the original recorders list by others, this record must be considered as, at best doubtful. [And,] in view of the fact that there is no confirmation of this record from later recorders and also the considerable distance to the nearest known sites, it would appear that this record should be considered erroneous, unless further evidence is forthcoming. However, Martin C. White [oneself] has examined this area and has found that there are at least two sites with suitable habitat within the forest which may have supported
tullia in the past.”
Your Dartmoor ideas seem to back my supposed intensive survey-work. However, I’ve absolutely no recollection of ever visiting Dartmoor or coming up with any two such sites. To say the least I’m flabbergasted. Though, with my interest now well and truly peeked I decided to try and find the best two paper sites for Dartmoor using my very impressive botanical database and an especial program. Maybe they just might match yours?
The programmable results offered a truly staggering 80 Dartmoor sites with four major extant Devon Large Heath occurring Axiophytes being concomitant. The quartet of plant species ordered in importance being: - Hare’s-tail Cottongrass, Cross-leaved Heath, Bog Asphodel & Round-leaved Sundew. To further clarify these results another fourteen axiophytes were added, again, arranged by foremost value. All sites were then ordered by being scored firstly for axiophyte numerical superiority and subsequently, within each numerical sub-set, their priority or value. The fourteen axiophytes in order: - White Sedge, Oblong-leaved Sundew, Bog Pondweed, Many-stalked Spike-rush, Heath Spotted Orchid, Marsh St. John’s Wort, Marsh Club-rush, Black Bog-rush, Bog Pimpernel, Marsh Helleborine, Tawny Sedge, Marsh Valerian, Bogbean & Royal Fern. This then gave a positive result for the two best paper sites out of the original eighty. First with 13 axiophyte species is an area just to the north-east of Postbridge, centred on two tetrads SX68V & SX68Q. And secondly, and very interestingly, an area not too far from its supposed station at Whitchurch, being just to the west of Princetown, centred on four tetrads SX57M, SX57S, SX57L & SX57R.
Direct translocation of stock from any of the abundant Northumberland sites where the climate and therefore possible evolved morphology is similar to Dartmoor may prove ideal for a successful establishment? I can supply whatever site details anyone might wish for such work. It is doubtful if habitat wind intensity is a great cause for concern, it isn’t elsewhere, release date duly excepted, of course. Should anyone require a full listing of my priority-ordered potential Dartmoor sites and full analysis, mentioned above, please send an email address. In properly surveying a large area for Large Heath it might also just be worth considering aerial photography when Hare’s-tail Cottongrass is seeding, showing-up as white fog-patches and efficiently illustrating any habitat or introduction site much better than a paper survey or any, hard-slogged, holistic ground-work.
Best wishes
Martin White
email:
martincwhite@talktalk.net