The key breeding species are reed bed specialists such as the marsh harrier, Eurasian bittern and bearded reedling, together with the avocet, the RSPB's symbolic bird. Bitterns stopped breeding on the reserve in 1989 due to inadequate habitat and a lack of sufficient large food fish; although European eels, a favoured food, are present, the numbers are too low. These problems were addressed by managing water levels and excavating some of the reed bed to create open, reed-fringed pools, and stocking the lagoon with the common rudd; breeding recommenced in 2004. In 2011, there were 80 avocet nests, two pairs of Eurasian bitterns, and four pairs of marsh harriers, the latter successfully fledging seven young.