Feral Mallards: A risk for hybridisation with wild Pacific Black Ducks in Australia?

Hybridisation is widespread in waterfowl and hybrids are often fertile. Mallards Anas platyrhynchos hybridise with numerous dabbling ducks and have been associated with decline in many Anas species with which they co-occur. Mallards have been introduced in Australia and New Zealand where they hybridise with indigenous Pacific Black Ducks Anas superciliosa. The extent of hybridisation in Australia is unknown, but Mallards pose a potentially serious threat to endemic duck populations and have already caused the extinction of some populations of Pacific Black Ducks in New Zealand, Lord Howe Island and Macquarie Island. The distribution and abundance of Mallards and the extent of hybridisation in Australia must be determined as a priority to ensure the long-term genetic integrity of the Pacific Black Duck.