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Amazing story of the hand-reared spiders

PUBLISHED: 09:12 21 October 2010

THOUSANDS of rare spiders - nurtured in the kitchen of a cottage - are to be released in the wild following a six-month labour of love by a conservationist.

Test tubes full of maturing raft spidersThe spiderlings – each just 4mm in length – have been bred and looked after in the home of Helen Smith on the Suffolk-Norfolk border.

They are young fen raft spiders – of a species sometimes known as the great raft spider – and are known to exist in the wild at only three sites including Redgrave and Lopham fen, owned by the Suffolk Wildlife Trust (SWT) and close to the headwaters of the River Waveney.

Dr Smith, a freelance consultant employed by Natural England, the Government’s wildlife agency, captured parent spiders from the Suffolk nature reserve and from another site, Pevensey Levels in East Sussex.

For five months she has overseen the mating of 18 pairs of the spiders and the production of about 4,500 young – at one time having to give them night and early-morning feeds, seven days a week.

Now they are ready to be released – in order to help ensure that the species survives in the future. Hybrid spiders – a cross between those at Redgrave and Lopham and Pevensey – are being released about 30 miles downstream on the Waveney, at Castle Marshes, between Lowestoft and Beccles. It is a new site for the spiders and will help ensure the survival of the species.

Pure-bred Redgrave and Lopham Fen spiderlings are to be released on their “home” reserve where extra pools have been created.

Dr Smith, who is the leading UK expert on fen raft spiders, said: “I mated the parents from Pevensey and Redgrave populations in the spring and reared around 100 offspring from each brood.”

As the breeding programme continued she gathered flies from dung heaps on Redgrave and Lopham Fen in order to feed the spiders. Currently she is using flies from her home compost heap.

“As a result of having the spiders in my kitchen I have learned more about the species over the past six months than I did through 18 years of fieldwork. I have been able to watch their whole life cycle at close hand.”

The fen raft spider was at one time thought to exist in the UK only at Redgrave and Lopham Fen and during the 1980s and early 1990s survival hung on a thread as the site dried out – partly as a result of the presence of a public water supply borehole. During drought conditions the pools in which the spiders live had to be “topped-up” with emergency supplies of fresh water.

However, a £4million restoration project, completed by the year 2000, restored the nature reserve to its former wetland glory.

The spider breeding programme, a joint initiative by Natural England and the SWT, has been grant aided by the BBC Wildlife Fund.

“The hybrids bring the advantage of increased genetic variability to the new population. This, combined with the use of Pevensey stock, from almost identical habitat in Sussex, should give the new population at Castle Marshes the best potential to adapt to its surroundings and to cope with the impacts of climate change,” Dr Smith said.

Site preparation for establishment of the new spider area at Castle Marshes included enhancing the ditch network.

“Castle Marshes has always been our first target for a new site in East Anglia because of the ideal habitat, the fact that it is on the same river as Redgrave and Lopham Fen and the huge enthusiasm of the SWT voluntary wardens,” Dr Smith added.

Monitoring of the newly-released populations will be carried out in collaboration with SWT volunteers and the Nottingham University spider lab.

An exhibition of work resulting from a fen raft spider artist residency with Sheila Tilmouth and based at SWT’s Carlton Marshes centre, will coincide with the release of the spiders.

The exhibition runs from October 25 to 28.

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