Help species make recovery

The Upper Thames branch of Butterfly Conservation, whose area includes Oxfordshire, is calling on people who enjoy seeing the great variety of butterfly species found in this country to take part in its recording scheme.

Volunteers will be very welcome at a time when a report on butterfly numbers shows cause for concern.

Figures for last year reveal that, as a consequence of the constant wet weather, butterflies suffered their worst year for over a quarter of a century. Several species had their lowest ever recorded numbers.

The report was by the UK Butterfly Monitoring Scheme, to which Butterfly Conservation is joined by the Centre for Ecology and Hydrology, whose headquarters are at Wallingford.

Eight butterfly species were found to be at an all-time low: the common blue, the grayling, the Lulworth skipper, the small skipper, the small tortoiseshell, the speckled wood, the chalkhill blue and the wall brown. The high brown fritillary and the Duke of Burgundy species, already in decline, also suffered.

The problem is caused by wet weather. Butterflies do not fly when it is raining so they are not able to reach the plants on whose nectar they feed, and are unable to breed.

With breeding numbers already affected, conservationists are waiting anxiously to see if populations can make a recovery this year.

More rain could lead to extinction for some species. So detailed information will be of particular importance. It will be needed in addition to the survey work which goes towards Butterfly Conservation's next five-yearly atlas of populations.

Observers are invited to record sightings in their gardens and in their local area.

For the purposes of the atlas, the country is divided into 10km squares, each of which has a 'champion' who co-ordinates records within this square. Each of these areas is sub-divided into what are called tetrads and the champions recruit volunteers to record in these.

Not all areas of the Upper Thames branch's territory are suitably covered. One area in which it still has a shortage is West Oxfordshire. Another is the border with Berkshire to the west.

Although the map for the branch's three counties - Oxfordshire, Berkshire and Buckinghamshire - covering the present five-year recording cycle begun in 2005 is encouraging, data even for the commonly seen species is very thin across West Oxfordshire.

There are many places where the butterflies are particularly likely to be seen, such as rough grassland, woodland clearings, along hedgerows, in churchyards and in domestic gardens.

Dave Wilton is atlas co-ordinator for the Upper Thames Branch. He explains what is required for the survey.

"The aim is to visit each tetrad at four different times, preferably in May, June and August, so that the flying times of all our local species are covered - at least once over the five-year period.

"An hour of your time spent walking along likely looking footpaths in your local area once or twice each week during the season to record the butterflies seen there could provide us with so much useful data.

"You don't have to do it all yourself - share a square with someone else, or enlist the help of others to assist you. All we need to know is that someone is looking after a particular area, so that we can target the gaps in our coverage more effectively."

There are also other surveys, run by members who specialise in butterflies in particular habitats, such as domestic gardens or in churchyards. Another study is of individual species, with each species having its own champion.

Studies of behaviour, abundance, range and habitat help the branch to determine the most effective conservation for each species.

Six species have already been 'championed': The adonis blue is a butterfly of the southern chalk downland, where it flies low over short-grazed turf, while the male has a brilliant sky-blue wings, the female is brown and much less conspicuous. A distinguishing feature of both are the distinctive black lines between the main colour of the wings and their white fringes.

The black hairstreak is another in decline. Its favoured food plant is the blackthorn and, occasionally, it is found on wild plum and other prunus species. Sheltered hedges and the edges of woodland are places where it is likely to be seen.

The brown hairstreak also feeds on blackthorn, and also finds a habitat in the tops of ash trees. The loss of blackthorn hedges has contributed to its decline, as has the annual flailing of those where the female has laid her eggs. The border between the bright blue of the wings of the chalkhill blue and their white fringe is a thin black-brown line. The females are brown with orange spots and a blue dusting near the body. The male is one of the larger blue species. Its sole food plant is the horseshoe vetch, for which it can be found searching chalk and limestone grassland.

The dark green fritillary is locally abundant but declining in central and eastern England. It is attracted to the common dog violet and, in the areas where they are found, also the hairy violet and marsh violet.

The dingy skipper is a small butterfly with a low, darting flight. It has become increasingly rare, but in sunshine may be found basking on bare ground with its wings widespread. In dull weather and at night it perches on dead flowerheads. Its habit of doing so, in a moth-like fashion, with wings curved, is not seen in any other British butterfly.

Information about taking part in any of the recording schemes can be found on the website of the Upper Thames branch of Butterfly Conservation: www.upperthames-butterflies.org.

As reported in last week's Oxford Times, a colony of the Brown Hairstreak was found at Long Close, Wood Farm, Oxford. David Redhead, of the Upper Thames branch of Butterfly Conservation, found eggs there from the species. There is just one other colony in Oxfordshire - along the county's boundary with Buckinghamshire.