RICHARD WILLIAMSON Nature Trails November 25

Common blue butterflies had a spectacular breeding success in Sussex this year, the second-highest number recorded since the bonanza drought year of 1976.

The closely-related brown argus also has its second-best year in 35 years.

The holly blue also did pretty well, with the sixth-highest number in the past third of a century.

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Butterflies from completely different families also did very well.

The small heath had its sixth-highest recorded number, while its cousin the meadow brown had its seventh-best year.

Ringlets had their fifth-best year too.

The figures come from my long-term research into butterflies numbers at Kingley Vale which began in 1976.

Once every week from April to September, I count every butterfly on the same five-mile walk through the reserve within a five metre wide area.

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This sampling technique, pioneered by Dr Pollard of the Institute of Terrestrial Ecology (ITE) research station at Monks Wood in Cambs (closed by the last government) was designed as a continuous Domesday record for future generations.

Here would be an accurate record of what was happening to butterflies over the decades.

Today 200 such samples like mine are taken from across the UK and now compiled by the UK Butterfly Monitoring Scheme at Lulworth in Dorset helped with government grants.

It is to be hoped these will continue.

Although butterfly numbers are governed by weather patterns, a large part of their success is due to management of their habitat.

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These days the South Downs are much more carefully managed for wildlife with downland grazed and scrub removed.

Good butterfly numbers this year show how well the turf at Kingley Vale is cared for.

The turf is grazed by rabbits and deer, of course, but the final touches are administered by sheep.

Another success for the present manager Katherine Birch is she has brought back that elusive little rarity, the dingy skipper butterfly.

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It vanished in 1995. Last year my transect picked up two of them, but this year I logged 19. This is very good news for the reserve.

Now, although the dingy skipper is in a completely different family to the common blue, both species need the same food plant for their caterpillars which is horseshoe vetch.

The reason that both these butterflies have done well this season is the downland turf at Kingley Vale is in its optimum state with large amounts of one of the principal components, horseshoe vetch. The total number of butterflies comprised of 30 different species this year was the ninth-highest ever, at 6,200. The best year was in 1991 with nearly 12,000.

These peaks come every six to eight years and when plotted look like a hospital heart graph.

The patient, it seems, is doing well, but it will continue to need the highest-possible care and expertise over the coming years.

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