Birds associated with a tailings storage facility and surrounding areas from a South African gold mine

As part of the 'International Cyanide management code for the manufacture, transport, and use of cyanide in the production of gold', companies voluntarily commit towards keeping the weak-acid-dissociable (WAD) cyanide concentrations in tailings below 50 mg l⁻¹. Day and night-time observations were made in winter at the tailings storage facility (TSF) of the Mponeng mine of AngloGold Ashanti, and extensive surveys of the surroundings were made for mortalities. The cyanide levels never exceeded 50 mg l⁻¹ WAD. No dead birds or mammals were found. Twenty-five bird species were recorded in and around the TSF and the associated return water dams (RWDs), with 20 occurring only in the surrounding grasslands or RWDs, and five (four wader species and a sand martin) on the TSF. The wading birds were most likely feeding on dead insects from the pond surface, as they adjusted their locations according to wind direction. Other birds actively avoided the TSF water, suggesting a locally learned behaviour. Whether this avoidance will also hold for migratory birds or natal dispersal of local birds in summer necessitates further investigation. A better understanding of the TSF-wildlife interactions would lead to improved measures to reduce environmental risks.