Sunday, 14 August 2016

A matter of perception ...

Meadow Pipit (Anthus pratensis)




Often overlooked due its unfortunate reputation for being an uninteresting species, A. pratensis is one of the most widespread and ubiquitous of all UK species. However, flocks of migrant A. pratensis are always worthy of closer scrutiny since they can be a good carrier for wagtails and rarer pipit species.

In spring, A. pratensis arrives back in Sussex to breed and many more pass through heading further north. Passage can begin in late February, but March and, to an extent, April are the key months. Although some birds may remain in Britain to overwinter, in autumn, most British birds head south, with many passing through Sussex on the way. Autumnal movements gain momentum in September through October and are often very evident at coastal sites with birds moving along the coast. Confusingly, such movements can be eastwards or westwards but the latter generally predominate and are often into the prevailing wind.

Throughout Sussex it is a bird of open, extensive rough and grassy habitats, from sand dunes and salt marshes to wet grassland, heaths and unimproved chalk grassland, where it feeds and nests on the ground. Take more attention next time you see one and appreciate the fact that it is common …

References:

Scott-Ham, M. (2014). Meadow Pipit. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 542-543.
Scott-Ham, M. (1996). Meadow Pipit. Birds of Sussex. Sussex Ornithological Society, pp. 398-399.

Wednesday, 3 August 2016

The sleeper ...

Small Tortoiseshell (Aglais urticae)

Chiddingfold Forest, 2016



The beautiful Small Tortoiseshell A. urticae can turn up almost anywhere and appears in gardens throughout the British Isles. It is one of our most successful butterflies. As its scientific name correctly suggests, it is most-often seen where nettles grow in abundance; both Common Nettle (Urtica dioica) and Small Nettle (U. urens) are used for egg-laying and larval nutrition. A. urticae is also frequently encountered whilst hibernating in an outbuilding, such as a garage, shed or barn, where they may be found in the company of other individuals. Further hibernation sites include hollow trees and woodpiles. I personally experienced some fifteen individuals overwintering in an old converted tractor shed last year. They were surprisingly first seen to be entering hibernation on 31st July 2015. They stayed in this state for eight months and only occasionally showed signs of any movement.

The adult butterflies can be seen on the wing at any time of the year, even on the last days of December or first days of January if the temperature is high enough to wake them from their dormancy. However, adults normally emerge from hibernation at the end of March and start of April. There are typically two broods each year, except in the north, where there is usually only a single brood. Whether single or double-brooded, the butterfly can be a familiar sight in late summer as it imbibes nectar to build up essential fats in preparation for its period of rest.

The above images show two separate males, the first, exhibiting dorsal thermoregulation on a forestry track in early July, the second, having successfully overwintered in the adult form, resting on a log pile in early April; the antennae tucked tightly between its forewings and showing the exquisite camouflage of the underside.

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Monday, 1 August 2016

15th August 1832 …

Lulworth Skipper (Thymelicus acteon)






To the lepidopterist the name James Charles Dale (1791-1872) will always be associated with the discovery of a butterfly new to Britain, Thymelicus acteon, the Lulworth Skipper. It is recorded, that on the 15th August 1832, Dale, having journeyed around twenty miles on horseback from his home at Glanvilles Wootton, reached Durdle Door, near Lulworth Cove. Here he found considerable numbers of acteon along the cliff tops. However, it was not until John Curtis reported Dale’s discovery in Volume 10 of his British Entomology, published in 1833, and named it the Lulworth Skipper, that the discovery was announced in print.

The female (pictured above) is quite recognisable from the pale orange crescent on her forewings, which is either lacking or very feint in the male. The male is generally darker in colour and has a distinctive sex brand on its forewings. As its name suggests, the distribution of this species is centred around Lulworth in Dorset, between Weymouth and the Isle of Purbeck. Colonies are most often encountered on south-facing, sheltered slopes, on chalk or limestone grassland, where tall patches of Tor-grass (Brachypodium pinnatum), its larval foodplant, can be found. In Britain, this species is at the northern limit of its range and is rarely found more than 5 miles from the coast.

The above images, in descending order, show (i and ii) a female on its larval foodplant, (iii) a freshly laid batch of eight eggs in the dried stem of B. pinnatum, (iv) typical acteon habitat overlooking Lulworth Cove with B. pinnatum in the foreground and (v) the view looking towards the northwest from its home on Bindon Hill.

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Friday, 22 July 2016

Precious metal ...

Large Skipper (Ochlodes sylvanus)


O. sylvanus typically inhabits sheltered areas of grassland where grasses grow tall. Classic sites include meadows, hedgerows, roadside verges, woodland rides and woodland clearings. It can also be found in urban areas, such as parks and churchyards. It can often be found basking on vegetation, or making short buzzing flights amongst vegetation. Like many other skippers, the male of this species alternates between perching, patrolling, basking and feeding. Patrolling behaviour is normally exhibited late-morning, with perching the norm in the early morning and afternoon. When perching, the males will defend their territory vigorously, and see off any butterfly that intrudes. Typical perches are sunlit leaves at a height of around a metre from the ground.


This is one of the largest of our ‘golden’ skippers and, like the others, the male has a distinctive sex brand on its forewings, containing specialised scent scales known as androconia. Their purpose is to disseminate pheromones in order to attract females during courtship; the strength of the pheromones diminishing with age. The adults are typically on the wing in June, through July, and into August. The above images, in descending order, show female and male from recent trips into local woodland.

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Tuesday, 12 July 2016

Alder-boughs and the flycatcher …

Spotted Flycatcher (Muscicapa striata)


M. striata breeds across most of the Western and Central Palearctic. It winters south of the Sahara, passing through the Sahel on migration. In Sussex it is a bird of woodland edges and man-made habitats such as churchyards, cemeteries, orchards, farmyards, gardens and parks. Woods with mature birch or ash and a diverse structure with features such as rides and glades are important, whilst ivy-clad trees make safe sites for nesting. It is often found near the edge of lakes, ponds and watercourses that are rich in insect life.

The future for M. striata in both Sussex and Britain does not look promising. It seems that the problems on the wintering grounds and migration route, including droughts in the Sahel region south of the Sahara, will have to be addressed, if possible, if the species’ fortunes are to be reversed. Here in Sussex, if more of our woodland can be brought back into suitable management, increasing the length of ride edge and the area of glade habitat and ensuring that ivy is not controlled by stem cutting, it will at least help those that make it here maximize their breeding success.

References:

Black, R. (2014). Spotted Flycatcher. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 502-503.
Parmenter, T. (1996). Spotted Flycatcher. Birds of Sussex. Sussex Ornithological Society, pp. 477-478.

Monday, 11 July 2016

Sunday, 10 July 2016

Equestrian pursuits ...

Purple Emperor (Apatura iris)

Chiddingfold Forest, 2016


For the last two weeks I have been spending a substantial amount of time walking both the known and lesser-known sectors of Chiddingfold Forest. The forest, situated in southwest Surrey and West Sussex, consists of a number of areas of mixed woodland, which together form the largest more or less continuous area of oakwoods in the region. Importantly, some areas hold Site of Special Scientific Interest (SSSI) designation. The variety of woodland types, the gills, and the rides provide habitats for a rich variety of insects and the site supports many nationally rare invertebrates and a number of regionally scarce bryophytes and lichens. The site is also noted for its diverse community of breeding birds.

Late June and early July is the time to search for that enigmatic of species the Purple Emperor. One thing that I have noticed this season is the apparent lack of aerial activity. During typical seasons, whatever typical may be, I’d expect to see males tree-topping and sallow-searching for females whilst ruthlessly defending their territories; I haven’t seen this once this year. With no basis for my conclusion other than gut instinct, I put this down to the generally less than favourable weather conditions experienced during this flight season - frequently cloudy, though warm and humid, and often with a strong breeze blowing. They’ve certainly been harder to find this season but putting in the time has certainly produced the results - I’d hate to think how many miles I’ve walked!

The above image shows a male photographed imbibing nutrients from dry horse dung on 8th July 2016. It was one of two seen grounded during this session.

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