SPRING 2003 No. 16

Page 3

DORSET WATER VOLE SURVEY, 2001-02

The Dorset Water Vole Survey of 2001-02 is now complete. Those of you who took part should have received a summary from me, I hope you enjoyed looking for Water Voles and again you have my thanks for making the survey possible.

The survey was conducted to see what, if any changes had taken place in the Dorset Water Vole population since the first survey in 1996/97. Encouragingly The 2001/02 survey found 91 (39.1%) sites to be positive for Water Voles. The 1996/97 survey found 79 (33.9%) of the same sites to be positive. This gives a slightly increased figure for Water Voles over the five year period between surveys.

If you look at the map, it is apparent that this increase is not uniform over the whole county. There has been a significant increase on the River Frome, with seven new sites found to be positive on the river. 69.4% of all sites on the River Frome were found to be positive for Water Voles and there has been an increase in the population range with Water Voles expanding further up the catchment. Gains were also noted on the Upper Stour where the strong population around Gillingham has strengthened so that voles can also be found on the Key Brook and the Caundle Brook. There have been new populations found in West Dorset on the Rivers Bride and Char. However, populations on the chalk stream tributaries off the River Stour have either stayed stable or decreased as is the case on the Moors River.

Other colonies that were recorded positive in the last survey were negative for this survey but appear to have ‘moved’ with positive records now being detected further downstream or in neighbouring areas. This effect is most notable on the River Piddle and in some coastal streams.

This increase in the Water Vole population has occurred while American Mink numbers have seamed to undergone a decline. There is quite a concentration of Otter records on the Upper Stour where the Water Vole population has strengthened, so it is possible that this increase in Water Voles can be attributed to the returning Otter population causing a decline in Mink numbers.

Additionally there has been an increased focus on habitat practices that could benefit Water Voles. The River Frome has been a focus area for agricultural grant schemes to encourage farmers to manage their land in a more sympathetic way for wildlife. The Environment Agency has carried out a number of ‘River Mending Techniques’ on the Rivers Stour and Allen to benefit fish stocks and river wildlife. Angling Clubs and Community Groups have also been encouraged to help wildlife along rivers. This should all help to stabalise the Dorset Water Vole population.

Future work should build on work already achieved to further strengthen the Water Vole population of Dorset through a combination of habitat safeguard and enhancement with possible Mink control if required in the future. This should be backed up with appropriate species monitoring, research and awareness raising. Work should be targeted to the four identified core Water Vole population areas but not exclusive to them.

Bronwen Bruce