Bourn Free

Graphic stating Pebble - projects that explore biodiversity benefits in the local environment

The Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire were awarded £5,845 for their Bourn Free project focusing on ecological surveying of the Bourn Brook, a tributary of the River Cam.

The project has been running since 2011 in partnership with the Countryside Restoration Trust. The PEBBLE fund, along with match funding from Anglian Water’s 'Water for Wildlife' programme, supported the surveying of the Bourn Brook for signs of water vole and otter – key species for indicating the health of a river. The surveying also included invasive non-native plants such as Himalayan Balsam and Giant Hogweed. These plants can be detrimental to our native species and can impact the health of the river.

Previous surveys had been completed along the Brook in 2011, 2014 and 2017 and the aim was to look for changes since the start of the Bourn Free project.

The surveys found that:

  • Giant Hogweed plants had decreased in numbers since the first survey in 2011, which had 91 records of Giant Hogweed and 17 records in 2019.
  • Records of Himalayan Balsam have not decreased but the density of plants has reduced from 2017 when the surveys started to record density.
  • In 2011 evidence of water voles was found in four locations along the Brook, in 2017 evidence of water voles was along the whole length of the brook and appeared to be a single population. In 2019 the survey results showed that water voles were closer together with less continuous distribution. The signs of water voles were greater in number but it is thought that the dry weather has resulted in some shallow sections of the Book being unsuitable habitat.
  • Evidence of otters had increased from 2011 to 2017, but had decreased in 2019, this is thought to be due to low flows in the river.

The PEBBLE fund also supported the Wildlife Trust in building an opportunity map to further improve river habitat along the Bourn Brook.

Photos of the Bourn Free project
Photos show Giant Hogweed in the Bourn Brook in 2015 and surveying the Bourn Brook in  2019.
Photos by kind permission of Wildlife Trust BCN.