About the reserve

At 3 miles long and 7 meters tall, Fleam Dyke, the great earthwork between Fulbourn and Balsham in Cambridgeshire, is a striking feature of the landscape. In 2023, we took ownership of a significant length of the Dyke, expanding and connecting the habitat to Fulbourn Fen.

Fleam Dyke’s chalk grassland supports a rich array of wildflowers. Spring brings violets and cowslips, followed by classic chalk species such as rock rose, horseshoe vetch, wild thyme, milkwort and eyebright. By summer, lady’s bedstraw surrounds knapweeds, scabious, clustered bellflowers, harebells, salad burnet, dropwort, restharrow and ploughman’s‑spikenard, with occasional squinancywort, sainfoin and pyramidal orchids. It is a great place to see butterflies and other insects; the chalkhill blue, grayling and grizzled skipper can be spotted as well as a number of moths, bees and grasshoppers. 

The area is also of historic interest. Built between the 4th and 5th centuries by Anglo‑Saxon settlers, the Dyke stretches three miles and rises seven metres from ditch to bank, likely serving as a defensive barrier. It later marked the boundary between the Flendish and Staine Hundreds, administrative areas recorded in the Domesday Book and used until the 19th century. Between 1912 and 1915, Fleam Dyke was one of 286 sites selected by Charles Rothschild, founder of the Wildlife Trusts movement, as a wildlife site worthy of preservation - the entire site is now a Scheduled Monument and a Site of Special Scientific Interest.

Learn more about Fleam Dyke