Opposite Grantchester Meadows, the land on the Trumpington side of the River Cam is Trumpington Fen, owned by the Pemberton family. Back in 2011 a project to establish a wetlands reserve of over 30 hectares was carried out in conjunction with Natural England and the Environment Agency under a Higher Level Stewardship agreement. The main aim was to create “a significant and undisturbed site for an assemblage of breeding and wintering wetland birds on the fringe of Cambridge”. The intention was to benefit waders and wildfowl during both the wintering and breeding periods and establish other wet grassland fauna and flora.
A wetland is described as a place where water covers or saturates the ground for prolonged amounts of time. In order to manage seasonal standing water of a few centimetres a project to re-engineer the former arable land was undertaken. The key changes were the creation of scrapes and gutters (shallow pond-like areas at river level), widening and re-profiling existing ditches and refurbishing or introducing sluices to control water levels when needed.
Once the extensive land work was carried out the area was seeded with a wide range of wetland meadow grasses, predominantly fescues. The wildflowers and rushes now appearing have grown up from the soil’s own seedbank and have been greatly influenced by the raising of the water level. Since establishment the flora has expanded organically and extensively, with birds also introducing new species of plants as they travel through.
Bird numbers on the Fen are tracked by the British Trust for Ornithology (BTO) during seasonal surveys across the Estate. Most notable residents on the wetland site are the endangered Red List species lapwings, yellowhammer and grey partridge. We have a lone little egret (Amber List) who, if he finds a mate, will be the first known nesting pair in the Cambridge area in recent times. Also on the Amber List are snipe, who are regular visitors now, reed bunting, teal, mallard and the greylag goose. Many of these birds are attracted by and feed on the nematodes and invertebrates that begin to occur when water levels are held at sufficient levels. Good numbers of water hen, coots and large flocks of chiffchaff, chaffinch and pied wagtail have been counted along with the odd buzzard. These birds are more attracted to the wild bird seed mixes that are planted adjacent to the wetlands, providing seed for overwintering birds and nectar sources for insects.
Aside from the wading birds enjoying the wetlands the nearby heronry has benefited from the reduced disturbance of regular cultivations the former arable land required. There were more than 10 nests counted in each of the last 2 breeding seasons at the heronry and already one early nest in March 2014 when it was anticipated that the other birds would begin repairs to storm damaged nests.
Grazing on the wetlands
Sheep are brought onto the wetlands during the summer months to further improve the ecosystem. A small visiting flock of sheep provided a light compacting of the newly cultivated ground during year one, followed by a larger grazing flock in year two (2013). The ground is now sufficiently naturally compacted and this summer we hope to tackle the issue of selective grazing by bringing both sheep and cattle onto the area. The manure from the livestock both adds nutrients to the land and provides a medium for insect life which in turn attracts the flocks of smaller birds.
As well as supporting an incredible abundance of biodiversity the wetland creates a buffer against extreme conditions like the floods that have occurred in both of the last winters. In this case they provide an important role in relieving pressure on Cambridge City during extreme periods of rainfall.