At the heart of Coatham Marsh is a series of pools and reed swamp; the last remaining wildlife habitats that have survived the industrial and urban reclamation of virtually the entire south Tees estuary. The reserve is bordered to the north by the dramatic Redcar blast furnace and to the south by residential areas of the town, but it still manages to provide a sanctuary for more than 200 species of bird and a wonderful variety of wildflowers.
Although it remained undeveloped the marsh has not been untouched by human activity. Small hummocks visible within the site are believed to be evidence of medieval salt extraction, rabbits were farmed close by at Warrenby (where streets were named after Coatham’s birds – plover, snipe, widgeon and teal) and a duck decoy was operated on the marsh until 1870.
A railway line and a freshwater fleet cut the reserve in two, although bridging points allow visitors to explore the whole of the reserve in a single visit. Two lakes on the southern side of the reserve; Long Lake and Round Lake, are man-made features associated with the extraction of soils used to cap mounds of furnace slag from the adjacent steelworks. These are fringed with dense reed-beds which provide nesting habitat for reed warbler, sedge warbler and grasshopper warbler in some years.
The mounds have been colonised by grasses and wildflowers with swathes of marsh orchids, clusters of bee orchids, as well as yellow rattle, eyebright and knapweed. Mammals such as fox and stoat can be seen and many smaller mammals must also be present as the grasslands are regularly visited by birds of prey including barn owl.
During the winter months, important numbers of ducks and waders including pochard, tufted duck and redshank fly in to Coatham Marsh to feed and rest. And with its proximity to the coast, it sometimes receives rarer visitors such as stone curlew, little egret, spoonbill and mandarin duck.
This 54 hectare site is owned by Tata Steel and has been leased and managed as a nature reserve by the Tees Valley Wildlife Trust since 1982.