Return to the Wildbrooks …

Bewick’s Swan (Cygnus columbianus)

The floodplain of the Arun valley ranges across a broad sweep of undisturbed wet grassland, intersected with wildlife-rich channels, surrounded by woodlands, and overlooked by the South Downs. It forms an essential part of the Arun Valley Special Protection Area for its large numbers of wintering wildfowl.

Although October records exist, it is generally mid November when the first of the Bewick’s appear in Sussex; three adults being present since at least 22nd November this year. After breeding in Arctic Russia, the swans undertake a 2,500-3,000 km migration to their wintering grounds. The vast majority head for Britain, the Netherlands and Germany, with smaller numbers wintering in Denmark, France, Ireland and Belgium. Sussex being located near the southwestern edge of their winter range.

A bird whose presence heralds the start of winter and embodies the atmosphere of the secluded wetlands of the Arctic tundra …

References:

Hughes, P. (2014). Bewick’s Swan. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 80-81.

Mason, M. (1996). Bewick’s Swan. Birds of Sussex. Sussex Ornithological Society, pp. 133-136.

First flight ...

Red Admiral (Vanessa atalanta)

Freshly emerged and waiting to take her first flight ...

More at: www.ukbutterflies.co.uk/species.php?species=atalanta

Emergence …

Long-tailed Blue (Lampides boeticus)

Saturday, 19th September saw the first of the 2015, Sussex born Long-tailed Blues’ emerge, with two females, found by Neil Hulme at Newhaven Tidemills. Following a lengthy break in proceedings, a pristine male was discovered at Beeding Cement Works, also by Neil, on Thursday, 8th October. Despite a rather slow start things still looked promising, as in 2013, for a mid-late October emergence.

However, by Monday, 12th October the weather began to cool and, with the ever-pending threat of overnight frosts, a cold northeasterly wind set in - though the weather remained generally dry and bright. High pressure was predicted to remain over the UK for at least ten days. Thursday, 15th October was cold and overcast with a daytime coastal high of around 12-13°C; the chilly northeasterly breeze still present. On a positive note, the frosts have stayed distant, at least to date, with overnight temperatures, on average, only dropping to around 7-8°C. Although wind chill is unlikely to stop emergence it would mean a lengthened development period and also less active adults when they finally emerged, consequently they would be much harder to locate. The presence of a hard frost would be a completely different matter!

Complete development of L. boeticus (egg to adult) can vary considerably with those individuals breeding in warmer climates being substantially quicker - as short as 28 days (Cribb, 2001) - compared with those in the cooler northern hemisphere - up to 58 days and possibly longer (D. Harris, 2015, pers. comms., 19 October; pers. obs., 2015); confirmed by a female, witnessed in the wild state, having emerged on Monday, 19th October after 22 days in the pupal stage and, with an estimated egg-laying date, some eight weeks earlier, of Saturday, 22nd August. Latitude, temperature, humidity and the nature of the seasons all undoubtedly play an important role in the development of L. boeticus. This is by no means unexpected nor is it exclusive to boeticus. For example, it is believed that some slow-developing larvae of the Mountain Ringlet (Erebia epiphron) may spend two years in the larval stage, usually the result of a late spring and a short summer period.

Weatherwise, Tuesday, 20th October was the day we all been waiting for - blue sky, sunshine, highs of 15°C and, finally, the cold northeasterly wind had abated. However, this only lasted for a day as Wednesday, 21st was wet and windy. Despite dull and overcast conditions, a freshly emerged female (pictured above) was discovered at Beeding Cement Works on Friday, 23rd October. I feel sure that the 2015 season is far from over and that we may still see fresh Sussex born boeticus in November …

More at:

Cribb, P. W. (2001). Breeding the British Butterflies. Edition 3. Orpington, Kent: The Amateur Entomologists' Society, 18, pp.49-50.

www.ukbutterflies.co.uk/phpBB/viewtopic.php?f=29&t=4065&start=2160#p104745

Northern Wheatear ...

Northern Wheatear (Oenanthe oenanthe)

Autumn passage ...

With its flash of white rump, the Northern Wheatear O. oenanthe is a rather smart, insectivorous passerine.

It has a vast range across most of Europe, the Palearctic and as far as Greenland and parts of Arctic North America. Astonishingly, as their ancestors before, all migrate to winter in Africa in a belt south of the Sahara - one of the lengthiest recorded migrations of any small bird. The British population is currently estimated (2014) at 230,000 pairs; most of which are concentrated in the uplands of the north and west. It is a very scarce summer visitor, though regular passage migrant during spring and autumn, along parts of the Sussex coast and Downs.

A bird I am always pleased to see …

References:

Yates, B.J. and James, P. 1996. Wheatear. Birds of Sussex. Sussex Ornithological Society, pp. 425-427.
Yates, B., 2014. Northern Wheatear. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 522-523.

Eggs-travaganza …

Long-tailed Blue (Lampides boeticus)

The search continues ...

A recent visit to a coastal site in Sussex, in search of adult L. boeticus, produced a single, brief, though welcome glimpse of a migrant male, on the last day of good weather.

Not to be beaten, Dan Danahar and I revisited the site the following day, Saturday, 12th September, in order to undertake a detailed and systematic search for L. boeticus ova. It was cold, windy and very overcast, with the threat of rain ever pending - ideal conditions for egg hunting as we would not be distracted from potential adult insects on the wing. Searching all the Lathyrus we could find and access, we ended up with an impressive grand total of 82 eggs. This included both freshly laid ova, as pictured above, and ova showing signs of larval emergence. One can only hazard a guess as to how many eggs had originally been laid and how many had been grazed away by the numerous snails that were present.

L. boeticus will lay its eggs both singly and in multiples on their selected foodplant. I have personally found as many as 5 ova on a single raceme, though have received reports from good authority of up to 9. Eggs can be found laid on the sepals (their apparent preference) and also on the petals and flowering stems of each inflorescence.

It's only a matter of time before freshly emerged Sussex born individuals take their first flight ...

More at:

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

www.markcolvin.blogspot.co.uk/2014/01/long-tailed-blue-in-sussex.html

www.ukbutterflies.co.uk/phpBB/viewtopic.php?f=29&t=4065&start=2120#p103939

Déjà vu …

Long-tailed Blue (Lampides boeticus)

The Long-tailed Blue, Lampides boeticus, (Linnaeus, 1767) is one of the most widespread butterflies in the world, being found throughout southern Europe, Africa, southern Asia, India and Australia, extending eastwards to parts of Oceania including Hawaii; however, it has historically been one of the rarest migrants to the British Isles.

2013 was an extremely exciting year for many migrant species, particularly in the southern counties. L. boeticus was once again recorded, with the first Sussex record coming on Thursday, 8th August, when a single female was observed and photographed in a garden in Arundel, West Sussex. 2015 has already seen records of L. boeticus. These range from as far west as Devon, on the 5th July 2015, through the southern coastal counties of Dorset, Hampshire, Sussex and Kent, and along the east coast as far north as Suffolk. Although two eggs, showing signs of larval emergence, were discovered in a West Sussex location on Friday, 21st August, suggesting a mid August primary migration, the first Sussex record of an adult came on Friday, 28th August, when a female was recorded in a private garden in Worthing, West Sussex.

I have been very fortunate in observing eggs, larvae and adults, including a mating pair, in Sussex. With our warming climate, I can’t help wondering if we may experience more frequent immigration of this beautiful little insect. Find a warm coastal location and, with at least some Broad-leaved Everlasting Pea (Lathyrus latifolius) present, you stand an increasing chance of finding the Pea Blue. A small selection of images from this season, depicting a female and ovum showing signs of larval emergence, are shown above.

More at:

www.dispar.org/reference.php?id=5

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

www.markcolvin.blogspot.co.uk/2014/01/long-tailed-blue-in-sussex.html

gorganus ...

Swallowtail (Papilio machaon ssp. gorganus)

Simply stunning ...

The British race of P. machaon, subspecies britannicus, is confined to the fens of the Norfolk Broads in east Norfolk. This is partly due to the distribution of its principal larval foodplant, Milk-parsley (Peucedanum palustre). The morphologically similar continental subspecies, gorganus, is less specific in its requirements and will use many kinds of umbellifer, for example Wild Carrot (Daucus carota) and Fennel (Foeniculum vulgare).

Following on from 2013 and 2014, both of which transpired to be exceptional periods for continental Swallowtail sightings in Sussex, with overwintered pupae from the 2013 breeding season emerging during May and June 2014, sightings of at least three plausible ‘migrant’ specimens have been recorded to date in 2015.

Pete Wong recorded the first, photographed in the meadow at Kithurst Hill on Saturday, 16th May. This sighting was not published at the time due to the vulnerable nature of this important site - the location already being under stress from footfall with the Duke of Burgundy season being well underway. However, there were no further sightings of this transient and slightly worn specimen. At the end of May an unsubstantiated report of more than one individual was noted from a location in East Sussex. Despite a published image, there is debate as to the authenticity and provenance of this report. Consequently, this is disregarded in this account. The next sighting came on Thursday, 30th July, when D Buck observed a worn individual near to the windmill in Rottingdean. The third report, of a specimen photographed by Helen Kalkbrenner near Nymans in Handcross, occurred on Sunday, 9th August.

Let’s hope this starts to trend, as it’s not out of the question with our climate continuing to become warmer, for this magnificent butterfly to take hold in the foreseeable future …

More at: www.ukbutterflies.co.uk/species.php?species=machaon

The bluest of blue ...

Adonis Blue (Polyommatus bellargus)

P. bellargus is a species of chalk downland, where its discrete colonies may be found in warm, sheltered locations.

The male - three separate individuals pictured above - has the most intensely coloured blue wings that gives this butterfly its name. It can be found flying low over vegetation, seeking out the less-conspicuous females that are a rich chocolate brown in colour. Like its close relative, the Chalk Hill Blue (Polyommatus coridon), the distribution of this species follows the distribution of Horseshoe Vetch (Hippocrepis comosa), which, in turn, follows the distribution of chalk and limestone grassland. However, this species has a more restricted distribution than P. coridon, indicating more precise habitat requirements. This butterfly can be found in large numbers where it does occur, such as the chalk downloads of East and West Sussex. Mill Hill, Malling Down, Cissbury Ring and High and Over are all reliable sites and each holds variable populations.

This is a warmth-loving species, preferring sheltered, south-facing slopes where the turf is closely-cropped, probably because it provides a higher temperature for the immature stages or because this is a requirement for the ant species that attend the Adonis Blue larva and pupa. The loss of grazing by rabbits, for example, can cause the sward to become overgrown and can render a site unsuitable for this beautiful species.

Quite simply a stunningly beautiful creature …

More at: www.ukbutterflies.co.uk/species.php?species=bellargus

Thecla ...

Brown Hairstreak (Thecla betulae)

The beauty of betulae ...

T. betulae is the largest Hairstreak to be found in the British Isles. It is a local species that exists in self-contained colonies that breed in the same area season after season. Despite this, it can prove extremely elusive, since it spends much of its time resting and basking high up in tall trees and shrubs.

Adults emerge in the morning with males generally appearing a few days before females. This is a warmth-loving butterfly and is rarely seen on overcast days. On sunny days the adults will rest with wings open, absorbing the sun's rays on their dark brown wings, which gradually close as they warm up. In flight, the adults are easily mistaken for the Gatekeeper (Pyronia tithonus), which flies at the same time. The day flying male Vapourer moth (Orgyia antiqua), though somewhat smaller than T. betulae, is also often mistaken for betulae by some observers.

The males are the more elusive of the two sexes, congregating high on ash ‘master trees’ that are positioned around the breeding area, where they feed on aphid honeydew. They occasionally come down to feed on various nectar sources, probably when honeydew is scarce. When they do come down they can be remarkably tame and easy to observe. This is one of the latest species to emerge in the British Isles, with adults first seen on the wing in late July or early August. There is one generation each year. Two separate females are illustrated above.

More at: www.ukbutterflies.co.uk/species.php?species=betulae

Chalk Hill Blue

Chalk Hill Blue (Polyommatus coridon)

As its vernacular name implies, P. coridon is found on chalk downland, although limestone downland is also used. The adult butterfly is most-often seen in bright sunshine, where the ground may appear to shimmer with the activity of hundreds, if not thousands, of males actively searching for a female just a short distance above the ground. The distribution of this species follows the distribution of its larval foodplant, Horseshoe Vetch (Hippocrepis comosa), which, in turn, follows the distribution of chalk and limestone grassland. This species is therefore restricted to England, south east of a line running from Gloucestershire in the west and Cambridgeshire in the east. It is absent from most of central England, northern England, Scotland, Wales, Ireland, the Isle of Man and the Channel Islands.

It is univoltine with the adults emerging in mid July in typical years, a peak being reached at the end of July and early August. The 2012 emergence in Sussex was exceptional with numbers not recorded since the mid 20th Century. A detailed evaluation, undertaken on 3rd August 2012, estimated a population of 820,000 individuals at one site alone. This mass emergence is believed to have occurred due to the wet conditions continuously suffered throughout the spring and summer of 2012, which, in turn, would have led to an exceptionally lush growth of nitrogen-rich larval foodplant. The sexes are strongly dimorphic. The males - a single individual illustrated above - being a beautiful pale sky blue and the females primarily chocolate brown. The adults use a variety of nectar sources, and the males will also visit, often in some numbers, moist earth or animal droppings to gather salts and minerals. This is a highly-variable species and many named aberrations exist. Catch them in the right light and the males are simply stunning …

More at: www.ukbutterflies.co.uk/species.php?species=coridon

Hulme, N. (2013). The 2012 Butterfly Year. The Sussex Butterfly Report. Sussex Butterfly Conservation. Issue 5, Spring 2013, pp. 12-15.

Time for bed ...

Common Blue (Polyommatus icarus)

Captured in the last rays of the evening sun a female Common Blue goes to roost …

Brown Argus

Brown Argus (Aricia agestis)

A. agestis is a widespread, warmth-loving species and, as such, is typically found in sheltered areas or on south-facing elevations. It can be found south of a line between Dorset in the west and southeast Yorkshire in the east, along with colonies in Derbyshire, North Devon and Cornwall. It is also found in north and south Wales, but is absent from central Wales. It is not found in Scotland, Ireland or the Isle of Man. Occurring in small, compact colonies, it is not a great wanderer, only travelling a couple of hundred metres, at most, from where it originally emerged. Like its close relative, the Common Blue (Polyommatus icarus), this species will roost communally on grass stems at night. In fact, the two species are sometimes found roosting together.

Two broods are common in central and southern England, with only a partial second brood in north Wales and the north of England. In good seasons, a partial third generation may be recorded in the south. The adults emerge first in central and southern England in early May, peaking at the end of May and the beginning of June, and giving rise to a second brood that emerges at the end of July. In north Wales and northern England, the first emergence starts in early June with any second brood appearing in early August.

Unlike most other members of the Polyommatinae, the ‘blues’, the Brown Argus has no blue scales on its upperside, both sexes being primarily brown in colour as its vernacular name suggests - although the butterfly can exhibit a bluish sheen when at certain angles to the light. Both sexes have beautiful orange spots on the upperside of both forewings and hindwings with the female - illustrated above - being more generously marked. It appears to be doing well in Sussex this season …

More at: www.ukbutterflies.co.uk/species.php?species=agestis