A case of infanticide in the Spot-billed Duck in circumstances of high breeding density

The first observations of infanticide by a precocial avian species, Spot-billed Duck (Anas poecilorhyncha), were recorded on a small pond at Yatsu tidal flat, central Japan, from May to June 2000, where six families of conspecific and one Gadwall A. strepera family, respectively, occupied territories. A female Spot-billed Duck with 11 ducklings attacked ducklings of all the other families killing eight conspecifics and three of the Gadwall. High breeding density (15.0 families/ha) may have increased the aggression of the female.