African Marsh Hamers Circus ranivorus perform aerial displays known as "sky-dancing" most frequently just before breeding and at other times during territorial takeovers. Both mares and females display and food supplements to seven pairs over two years verified sexual selection arguments that birds in better condition display more freuently than unfed controls. Typical sky-dancing birds soared to 400 m or more, and performed up to 20 U-shaped undulations in a horizontal plane, while sky-spiruffing birds performed vertical displas, dropping in a series of descending U-shaped undulations, whilst twisting about their axis. Displaying girds stimulated others to perform and up to eight birds displayed in the same aerial arena.