Main dam, approximately 6ft high

Ryenats were very fortunate to be offered the chance to visit the site of the beaver introduction in Cropton Forest. We met on two separate occasions, following Covid guidelines in groups of six, led by Cath Bashforth and Nick Gibbons – many thanks to both of them.

The site incorporates the remains of ornamental boating ponds from an old Victorian planned landscape, The man-made dams were derelict, with an obvious breach in one of them. The first thing the beavers did on release was to plug this gap and start to re-fill the pond. Since then, in the eighteen months or so they have been on the site, they have done a huge amount of hydro-engineering – it is very impressive to see what they have achieved, especially given the size of the family – two adults, two part grown youngsters from last year and two new kits born this summer. Apparently they gnaw part way through a tree and then leave it for the wind to bring down.

Tree part-felled by beavers

Tree felled by beavers

As well as felling a considerable number of trees – which has let a lot more light in to the beckside area to improve the biodiversity (Nick hopes the open water might attract Daubenton’s bats) – the beavers have built an impressive dam and a lodge to live in as well as deliberately raising the banks of the pond (now more of a lake as it has merged with the beck itself) to raise the water level further.

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Beaver dam plugging gap, with raised bank to the right

When the animals were first released they were provided with two artificial lodges to shelter in, but they very quickly decided these were not to their liking and built their own! The artificial ones are now partly underwater as the levels have risen by several feet. The main dam is built from fairly substantial branches and tree trunks – it is amazing that the beavers can manipulate such large pieces of timber. Recently they have also started planting the roots of yellow flag iris, moved from within the lake, onto the top of the dam on the downstream side. We are not sure why they do this – is it to bind the dam with growing plants, to provide a source of food in winter (they do eat the iris), or do they just want a garden?

Beaver lodge. The entrance is at the back, underwater from the beck

You can see all Nick Fraser’s photos in an album here.

Please see the Forestry Commission site https://www.forestryengland.uk/beaver-trial-cropton-forest for further information on the project.