Saturday, 25 June 2016

Heddon pleasures ...

High Brown Fritillary (Argynnis adippe)

Of sea nymphs and hidden valleys …



The Heddon Valley, located in the northwest corner of Exmoor, is a deep, lush wooded river valley running down to the cliffs and tides of the Bristol Channel. It boasts one of the best populations of A. adippe in the UK, which can be found flying from around mid June to mid-late July. June 2016 found me heading west once again and the comfort of the Hunters Inn, my base for three days.

A. adippe is a butterfly over which there is much concern due to its dramatic decline in the UK. Although there has been some recovery at sites which are specifically managed for this butterfly, the High Brown Fritillary is one of our most threatened species whose numbers have plummeted since the 1970s, being extinct over 94% of its former range. Factors causing this decline are said to include habitat loss and fragmentation, a reduction in woodland coppicing - a practice which opens up new areas of suitable habitat that the butterfly is able to colonise once existing sites have become overgrown, agricultural improvement and lack of grazing and traditional forms of bracken management. The woodlands of East and West Sussex used to boast the UK’s leading adippe colonies. Sadly, it has certainly been extinct in West Sussex since at least 1986 and in East Sussex since 1987. Once common and widespread in large woodlands in southern, central and north-west England and parts of Wales, adippe is now confined to a decreasing number of sites including in the Morecambe Bay area of north-west England, North and South Devon (including Dartmoor), Exmoor in South Somerset, and a few sites in Glamorganshire including the Alun Valley near Bridgend.

Easily mistaken for its close relative the Dark Green Fritillary Argynnis aglaja, the two species are most easily distinguished by their undersides, where A. adippe has a row of brown spots between the outer margin and the silver spangles, which are missing in A. aglaja. A less-reliable identification guide is that, as its name suggests, the High Brown Fritillary has a predominately brown hue to the underside, whereas the Dark Green Fritillary is predominately green. The two species often fly together making a positive identification almost impossible unless the butterfly is at rest.

Two images of males above with more to process when time allows ...

More at:

Pratt, C. R. (2011). A Complete History of the Butterflies and Moths of Sussex. Peacehaven, East Sussex: Colin R. Pratt, 2, pp. 267-272.

www.ukbutterflies.co.uk/species.php?species=adippe

Sunday, 19 June 2016

No pain, no gain …

Large Heath (Coenonympha tullia ssp. scotica)

Inverness-shire, June 2016




Found in the north of the British Isles, C. tullia is unique in that it is more or less confined to boggy habitats. It lives on the British mainland in isolated colonies from central Wales in the south to Orkney in the north, and also in scattered colonies throughout Ireland. It is absent from Shetland.

The eyespots on the underside vary considerably. Those in the north have almost no spots at all with adults looking very similar to a large Small Heath (Coenonympha pamphilus), while those in the south have very distinctive spots. This has given rise to three named subspecies. Those with the least distinct spots are referred to as ssp. scotica, those with the most distinct spots as ssp. davus and those that are intermediate as ssp. polydama. This species forms a typical cline and, unsurprisingly, intermediates occur between the three named forms. Subspecies scotica is found in northern Scotland, north of a line between the Clyde Isles in the west and North Aberdeenshire in the east. It is found in most of the western isles and is also present in Orkney. The primary larval foodplant is Hare's-tail Cottongrass (Eriophorum vaginatum). Common Cottongrass (Eriophorum angustifolium) and Jointed Rush (Juncus articulatus) are also used.

The two males pictured above are from Inverness-shire and were photographed early one morning during the biggest emergence of biting midges I have ever experienced - they got everywhere!

More at:

Friday, 17 June 2016

Moorland memories ...

Golden Plover (Pluvialis apricaria)

North Yorkshire, April 2016


One of my target species during a recent trip to the North Yorkshire moors was the Golden Plover (P. apricaria). This male, one of very few I found, was located in April in the Yorkshire Dales National Park.

A bird that is always a pleasure to see …

Thursday, 16 June 2016

Chatting on the moors ...

June 2016

Whinchat (Saxicola rubetra)




The Whinchat (Saxicola rubetra) is a fairly common passage migrant, although rare summer visitor, to Sussex. Most birds pass through in late April and May, with some stragglers being recorded at coastal locations up to the end of May and even early June in some seasons. Despite there being apparently suitable breeding habitat in the county, they are very rare breeders in Sussex. In Britain, S. rubetra mainly breeds in northern and western upland areas with a few in Ireland. Whinchat numbers in Britain more than halved between 1995 and 2008, the cause(s) being unknown. The above images were recently taken on moorland in North Wales and show in descending order males (top and middle) and a female (bottom).

References:

Scott-Ham, M., 2014. Whinchat. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 516-517.

Sunday, 12 June 2016

New beginnings ...

Chequered Skipper (Carterocephalus palaemon)

Scotland, 2015 and 2016




As part of his ongoing research project, Monday, 6th June 2016 found me returning to Scotland with Pete Eeles in order to visit a number of sites during the Chequered Skipper’s flight season. These included Glasdrum Wood, by far the easiest site to both access and observe this rare and beautiful insect, Ariundle, Glen Loy, Loch Etive, Allt Mhuic, Glen Nevis and several areas around Spean Bridge.

The first adult palaemon of the 2016 flight season was reported from Glasdrum Wood on 12th May. As the adult has a relatively short flight season we were not expecting to find many, if any, pristine specimens; the best we found, a female, is pictured above. Our main objective was to observe behaviour including that of egg-laying females - we were not to be disappointed.

As mentioned in my earlier post, Lair of palaemon, the area that C. palaemon inhabits is notable for its climate, warm and wet, with a long growing season and one of the highest rainfalls in Britain. Both are important to the larvae and the range of C. palaemon coincides closely with that of this climate. Indeed, its range appears to be determined by the requirements of the larval stage including the abundance of suitable foodplant alongside soil-enriching plants such as Bog Myrtle (Myrica gale). Features important to the adults include shelter, abundant nectar sources and areas that provide favourable conditions for mate location.

In descending order the above images show (i) a female at rest on bramble and (ii and iii) two eggs that were observed being laid.

My thanks once again to Pete for allowing me to share in his research and for his good company during our recent expeditions. Watch out for his paper in the not too distant future, which promises to be an illuminating read …

More at:

Ravenscroft, N.O.M. (1992). The Ecology and Conservation of the Chequered Skipper Butterfly Carterocephalus palaemon (Pallas). Unpublished Ph.D. thesis, University of Aberdeen.

Saturday, 11 June 2016

Lair of palaemon ...

Chequered Skipper (Carterocephalus palaemon)

Scotland, 2015 and 2016






One thing that Pete Eeles makes you realise is that finding the impossible is possible; it just takes dedication, patience and hard work - with good eyesight being an added bonus! Although I have not managed to find as much time as I would like to have done, I have been very fortunate to have visited Scotland on a number of occasions during the last two seasons. My target, with Pete’s guidance, was all stages of the beautiful and enigmatic Chequered Skipper (C. palaemon).

Though sadly declared extinct in England in 1976, C. palaemon was formerly found along the rides of wet deciduous woodland and associated areas of limestone grassland of central and eastern England, where False Brome (Brachypodium sylvaticum) was used as the larval foodplant. C. palaemon is now confined to north-west Scotland where it was first discovered in 1939 at Loch Lochy in west Inverness-shire; its distribution being centred on Fort William and where the larval foodplant is Purple Moor-grass (Molinia caerulea)The area that C. palaemon inhabits is notable for its climate, warm and wet [with plenty of midges and ticks], with a long growing season and one of the highest rainfalls in Britain. Both are important to the larvae and the range of C. palaemon coincides closely with that of this climate. Indeed, its range may well be determined by the requirements of the larval stage including the abundance of suitable foodplant.

My early visits in 2016 involved searching for post-hibernation larvae and more latterly the pupae, a difficult process but one made somewhat easier by the discrete marker system used in Pete’s study. The pre-hibernation larvae are green (matching the green leaves of the foodplant) whereas the post-hibernation larvae are brown, perfectly matching the colour of the dead leaves of M. caerulea. It takes a while to get your eye in but once you know what you are looking for it gets easier – but certainly not easy!

In descending order the above images show (i) the author searching M. caerulea at Glasdrum Wood in April for final instar larvae, (ii) a post-hibernation [final instar] larva, (iii) two images of larvae preparing for pupation and (iv) a pupa at an early stage in its development.

My thanks to Pete for allowing me to share in his research project.

More at:

Ravenscroft, N.O.M. (1992). The Ecology and Conservation of the Chequered Skipper Butterfly Carterocephalus palaemon (Pallas). Unpublished Ph.D. thesis, University of Aberdeen.