Malcolm Bridge has been Butterfly Recorder for the Surrey/South London Branch of Butterfly Conservation since 2000, collating data for Surrey south of the Thames, and into London as far east as Rotherhithe. Records are collected for 1 kilometre square areas. The latest publication is for the four-year period 2005-2008 and includes returns for most of these areas. Malcolm illustrated the form of presentation of data with a summary distribution map, giving the total number of species recorded in each square as colour-coded dots representing ranges 1-5, 6-14 and 15+ species. Similar maps are compiled for the numbers recorded for 41 individual species.
Some species which have been seen in the past in the county have apparently disappeared, notably the Duke of Burgundy, last reported in 1997, and the pearl-bordered fritillary, last recorded in 2006. The current preference in woodland management for timber production rather than coppicing is undoubtedly responsible in the latter case. A totally different cause, parasitism by flies and wasps, has reduced the numbers of small tortoiseshell.
Other species such as the wall, which was once common, and the dingy skipper occur only in small numbers in specific areas, respectively Box Hill and around Compton.
Encouragingly there are increases. The silver-spotted skipper, hitherto confined to the warmer southern slopes of the North Downs, has spread to the northern side, in particular the Headley Heath area. Also the marbled white has become common in the Downs region.
Some species, while occurring in reasonable numbers, are localised, such as the wood white around Chiddingfold and Dunsfold. Surrey also boasts a speciality, the silver-studded blue, found towards the west of the county, and even as close as Fairmile.
Rarer migrants are always exciting news. In August a swallowtail was observed in Laleham. Occasionally long-tailed blues can be seen in the Denbies area, and even large tortoiseshell and Camberwell beauty were reported not so long back.
During his talk Malcolm showed high-quality photographs of more than 40 butterfly species. A number of points of interest were made on the way. Recording problems exist, such as confusion in identification, for example between the small and the holly blue. Both have markings on the underside of the wings which are not easily distinguished, but they are seen to be spots and dashes respectively on careful inspection. Other species are not easily observed for population estimates. Egg count is more reliable for the brown hairstreak. The eggs are large and white and easily spotted in the forks of branches on bushes.
One fascinating feature of butterflies is the variation in life history between species. Looking at one aspect, the date the adult's first season ends, there is the contrast between the peacock, which begins to hibernate in August, and the red admiral and brimstone, which can be seen roosting among ivy in winter. Again breeding characteristics can show remarkable individuality. As an example the comma is one species which produces a second brood, but more uniquely this has a different colour, being slightly brighter, and does not breed, but merely hibernates.
Malcolm ended by showing photographs of a few moth species, among them the Jersey tiger which, as it is strikingly coloured and flies during the day, can be thought to be a butterfly.
David Morgan