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!

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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.

Saturday, 28 May 2016

Early morning blues ...

Small Blue (Cupido minimus)

West Sussex, 23 May 2016



C. minimus is our smallest resident butterfly with a wing span that can be a little as 16mm. The sexes are similar in appearance, although the male (top image) upperside is almost black with a light dusting of blue scales, whereas the female (lower image) appears dark brown in colour. Both sexes have an underside that is silvery-grey, which is not dissimilar to that of the Holly Blue (Celastrina argiolus).

This beautiful little butterfly has a large distribution, being found from northern Scotland to the south of England, with colonies also in Wales and Ireland. Outside of its strongholds in the south of England, colonies are often merely isolated pockets, typically in coastal locations, with most populations consisting of just a few dozen adults. In Sussex, minimus has not yet recovered from the weather-related population crash occurring between 2007 and 2012. With 2015 having been a testing season for this species, we wait with some trepidation as to its fortunes in 2016.

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Thursday, 26 May 2016

A is for aberration ...

Duke of Burgundy (Hamearis lucina)

West Sussex, May 2016




When it comes to natural selection, we should consider two classes of aberration [a characteristic that deviates from the ‘normal’ type] - those that are passed from generation to generation in the species’ genetic make-up, and those, which are not e.g. those that are determined by the environment. Such variation may be caused by changes or mutations in the genetic composition as the individual develops, or to changes in the physical makeup of the individual as a result of environmental conditions. Aberrations caused by environmental factors e.g. extremes of temperature, are probably not influenced by natural selection since they are not part of the gene pool and are therefore not likely to be inherited; this includes certain examples of colouring and markings. Aberrations may also be the result of a reproduction ‘error’ that is neither genetic, nor associated with the environment, such as gynandromorphs and hybrids.

Those aberrations that are carried in the gene pool [and from generation to generation], and that are visible in terms of colour and markings, clearly do not provide the population with any advantage otherwise they would be widespread. This is where the term ‘aberration’ really doesn't stand up to scrutiny. An individual is considered an aberration if it deviates from the norm. But if it becomes widespread, it is the norm and therefore no longer an aberration. A case in point is ab. caeruleopunctata (Rühl, 1893) in the Small Copper (Lycaena phlaeas) that has a row of blue spots above the copper marginal band on the hindwing. It could be argued that individuals without the blue spots are actually the ‘aberration’ in some populations where this feature occurs frequently. However, answering the question of why this occurs, these aberrations should simply be seen, in my opinion, as a reflection of the rich gene pool available that potentially allows populations to respond to changes in their environment.

2016 has been a good season for aberrant Duke of Burgundy in Sussex. In descending order the above images show a ‘normal’ female, a female referable to ab. albomaculata (Blachier, 1909), and a rather exciting find of a female currently referable to ab. gracilens (Derenne, 1927) + ab. albomaculata (Blachier, 1909). However, with regards to the third individual, albomaculata is only a hindwing aberration whereas this specimen has the same condition on the forewings as well. In addition, the spots in the lunules to the forewings are streaks instead of spots. The underside was also of a paler appearance than ‘normal’. It is therefore quite possible, as none of the existing combinations of names really cover it, that a new name may be required for this form.

My thanks to Peter Eeles, Alec Harmer and Rupert Barrington for their assistance.

More at:

Ford, E.B. (1945). Butterflies. London: Collins (New Naturalist), pp. 219-247.
Harmer, A.S. (2000). Variation in British Butterflies. Lymington, Hampshire: Paphia Publishing Ltd., pp. 53-96.

Wednesday, 11 May 2016

Beacon of the bog ...

West Sussex, 8 May 2016

Bog Beacon (Mitrula paludosa)



M. paludosa grows to around 4cm tall, has an ovoid or club-shaped yellow or orange swollen fertile head, which is held aloft on a delicate white or translucent stem. M. paludosa is a saprotrophic fungus [feeding on dead organic matter] and is usually found on the remains of higher plants, mosses and algae in areas of seeping or standing water. Although widespread in Britain it can be difficult to find and, despite its bright orange head, easily overlooked.

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Friday, 6 May 2016

Abiding beauty ...

West Sussex, 5 May 2016

My first this season ...

The beautiful but vulnerable Pearl-bordered Fritillary.


Once considered common and widespread, including throughout my home county of West Sussex, the Pearl-bordered Fritillary is now one of our most-threatened species. The cessation of coppicing which resulted in the loss of suitable habitat is believed to be one of the major causes of this drastic decline. Conservation efforts have therefore focused on habitat management and there have been a number of success stories. However, this butterfly is still declining and, as such, continues to be a priority species for conservation efforts.

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