Water Voles.

Water Vole Survey 2010, Ransonmoor and Curf Fen

In 2010 a survey of the distribution of water voles within two different drainage board districts – Ransonmoor District Drainage Commissioners and Curf Fen, part of Wimblington Combined IDB. This was carried out as a post graduate project by Yuping Chen, studying at the University of East Anglia.

It repeated a survey carried out by The Wildlife Trust, Cambridgeshire in 2005 of the same areas. The results showed that the water vole population in drainage board maintained ditches at Ransonmoor was still at the high level of occupation of the 2005 survey, over 80%,  but occupation in Curf Fen maintained ditches, (Wimblington Combined IDB), had increased during the five-year interval from 61% to 74%. There was also an increase in water vole populations in the privately owned side ditches at Curf Fen from 25% to nearly 32%.

                                           Curf Fen                   Ransonmoor
Ditch type (number) Drainage Board Maintained (57) Side ditch, (privately maintained) (60) Drainage Board Maintained (84) Side ditch,(privately maintained) (107)
Survey year 2005      2010 2005 2010 2005 2010 2005 2010
Water Vole Presence (%) 61.4      73.7 25.0 31.7 85.7 82.1 20.6 20.6

Re-profiling, or side-trimming of ditch banks has been often regarded as potentially harmful for water vole populations This study showed however that re-profiling done within recent years (2008 and 2009) at Curf Fen seemed to benefit a higher distribution of water voles. The strong correlation potentially suggested that careful bank management could maintain or improve habitat diversity in the long term. Nevertheless, it may also be biased by other factors that coincided with recent re-profiling sections, such as a better habitat quality that allowed populations to recover more quickly. To verify whether the current strategy on bank re-profiling is really improving the vole distributions, further monitoring on bank re-profiling is needed.

In the five years between surveys several wind turbines had been constructed within the Ransonmoor District. The survey showed that their presence had no significant effect on the distribution of water voles in adjacent ditches.

The full dissertation can be viewed here – AN INVESTIGATION OF THE ENVIRONMENTAL FACTORS THAT AFFECT THE WATER VOLE (Arvicola terrestris) DISTRIBUTION IN TWO FENLAND DRAINAGE BOARDS, CAMBRIDGESHIRE