Saturday, 31 May 2014

Black magic ...

Black Guillemot (Cepphus grille)


The Black Guillemot (C. grille) is a very rare vagrant to the coastal waters of Sussex with only fifteen individuals recorded as of 2010. The British population, which is of the subspecies C. g. articus, is the second largest in Europe only to Norway and contains approximately 38,000 individuals (Seabird 2000) out of a European population 100,000-200,000 breeding pairs. Its UK distribution is very biased towards the far north and west, half of the population breeding in the Northern Isles, particularly Shetland; the nearest breeding populations to Sussex are small populations in southeast Ireland and Anglesey.

They typically nest in crevices or cavities between boulders, and occasionally in holes in harbour walls. Diving to feed, their diet is comprised of small bethnic fish and crustaceans.



References:

Hobson, J., 2014. Black Guillemot. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 346.
Fairbank, R., 1996. Black Guillemot. Birds of Sussex. Sussex Ornithological Society, pp. 347-348.

BirdLife International (2014) Species factsheet: Cepphus grylle. Downloaded from www.birdlife.org on 31st May 2014.

Friday, 9 May 2014

Spring pearls ...

Pearl-bordered Fritillary (Boloria euphrosyne)



This beautiful woodland butterfly occurs in scattered and isolated colonies south-west of a line running between Denbighshire in the north-west to East Kent in the in south-east. There are also colonies in Westmorland and West Lancashire. It is also widespread in central Scotland, but very local or absent in the north and south of the country. In Ireland, it is found in the Burren limestones of Clare and southeast Galway. It is absent from the western and northern Isles of Scotland, the Isle of Man and the Channel Islands. B. euphrosyne survives in West Sussex thanks to carefully managed Sweet Chestnut coppice in several important woodlands which allows the Common Dog-violet (Viola riviniana), the main larval foodplant, to grow in appropriate conditions.

This is the earliest of our fritillaries to emerge. In good years, the butterfly emerges at the end of April in the south. Most adults emerge at the start of May, but may not appear until the end of May in more northerly locations.

B. euphrosyne is typically found in deciduous woodland containing open areas, such as woodland clearings, that provide the right conditions, foodplants and nectar sources for this species to survive. Suitable sites are generally habitable 2 to 4 years after a woodland clearing has been formed, when the foodplants and nectar sources are optimal for this species. However, these sites can quickly become overgrown and, unless there is suitable habitat nearby or regular habitat management undertaken, colonies are often lost.

Larvae feed by day and generally rest in leaf litter, but can also be found, especially after hibernation, basking on dead bracken. They eat the entire leaves, leaving just the stem intact. They will also feed on only the leaf lobes, at the base of the leaf, leaving characteristic feeding damage that can give away the presence of a nearby larva. After moulting for the third time the larva enters hibernation, generally in a dried leaf, emerging in the spring to complete its growth. There are 4 moults in total.

The two images show a male, referable to ab. interligata, Cabeau (1919) + ab. transversa, Vorbrodt (1911) recently found in West Sussex.

Thursday, 1 May 2014

On your marks, get set …

Brown Hare (Lepus europaeus)


The taxonomic Order Lagomorpha comprises the hares, rabbits and pikas. The Brown Hare (L. europaeus) is the largest of the British lagomorphs. Since there is no evidence of their presence in Britain before Roman times, it was probably introduced by man. They are widespread on low ground throughout England and Wales. In Scotland, L. europaeus is found on farmland and rough grazing to the far north of the mainland, but is absent from parts of the North West. L. europaeus is replaced by the Mountain Hare, L. timidus, in upland areas of Scotland and central England.

Brown hares generally live in exposed habitats, and they rely on their acute senses and running at speeds of up to 70kph (45mph) to evade predation. Hares do not use burrows, but make a small depression in the ground, known as a form, amongst long grass. They spend most of the day on or near the form, typically moving out to feed in the open at night. Tender grass shoots, including cereal crops, are their main foods. Though generally solitary, hares sometimes band into loose groups when feeding.

Breeding takes place between February and September and a female can rear three or four litters a year, each of two to four young. The young, known as leverets, are born fully furred with their eyes open and are left by the female in forms a few metres from their birthplace. Once a day for the first four weeks of their lives, the leverets gather at sunset to be fed by the female, but otherwise they receive no parental care. This avoids attracting predators to the young at a stage when they are most vulnerable. Foxes are important predators of young hares and where foxes are common there are likely to be very few hares. Adults typically live to 3 or 4 years.

Numbers of hares have declined substantially since the beginning of this century, though they are still locally common animals in many parts of the country. The main reason for this decline seems to be a change in the way modern agriculture is managed. Today's farms are often intensive and specialised, either growing crops like wheat and oilseed rape, or raising livestock for meat and dairy produce. A hundred years ago most farms were varied enterprises. Mixed farms have a patchwork quilt of fields, which provide year-round grazing for hares as well as long crops for them to hide in. Modern cereal farms provide little or no food for hares in late summer and autumn, and livestock farms have few crops for them to shelter. Modern farm machinery and pesticides also kill many hares.

References:

Bjärvall, A. and Ullström, S., 1986. The Mammals of Britain and Europe. Beckenham, Kent: Croom Helm Ltd., pp. 60-62.
Corbet, G. B. and Harris, S., (eds.) 1991. The Handbook of British Mammals (3rd Edition). Oxford: Blackwell Scientific Publications, pp. 154-161.

The Mammal Society (2014). Species fact sheet: Brown Hare (Lepus europaeus). Downloaded from www.mammal.org.uk on 1st May 2014.