Rosser's Sac Spider
The Rosser’s Sac Spider (Clubiona rosserae) was one of the first endangered species that Buglife worked on. Historically, it has been known from only 2 sites in the UK which are both located in the Cambridgeshire Fens. In 2002, Buglife put together a project with Anglian Water and the British Arachnological Society to find the little spider and understand better how to conserve it.
Quick Facts:
- Name of Project: Rosser’s Sac Spider
- Duration of Project: 2002 – 2006
- Location of Project: Cambridgeshire Fens
- Species benefiting from Project: Rosser’s Sac Spider (Clubiona rosserae)
- Project funded by: Anglian Water and English Nature
- Project Partner: British Arachnological Society
Project Aims
This project aimed to secure Rosser’s Sac Spider from extinction in East Anglia and the UK, and improve the management of fenland habitats for spiders in general.
What did Buglife do?
Buglife chaired the steering group and managed the field worker who studied the Rosser’s Sac Spider and surveyed known and potential sites. Anglian Water sponsored the work on the spider. English Nature provided additional financial support and supported a University of East Anglia PhD student to study spider ecology. The British Arachnological Society provided volunteer specialists and spider expertise.
Rosser’s sac spider is an internationally very rare wetland species that has only ever been found at two sites in the UK. Despite intensive searching by Buglife and the British Arachnological Society between 2002 and 2006 we were unable to locate a population of the spider. With the last sighting in 2000, we fear were that the spider had died out in the UK.
In addition, we learned more about fenland management for spiders and shared these learnings with landowners.
Project Update
In September 2010, Ian Dawson of the British Arachnological Society found a female in a pile of cut vegetation very close to where the species was seen in the early 1990s.This is the first record from the UK for 10 years, and the first record from Chippenham Fen for 14 years. Unfortunately, a further Buglife survey of Lakenheath Fen RSPB reserve failed to relocate that population.
The Rosser’s Sac Spider Species Recovery project was funded by Anglian Water and English Nature.
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