Page "Mallard" Paragraph 38

In the cases mentioned above, however, ecological changes and hunting have led to a decline of local species ; for example, the New Zealand Grey Duck population declined drastically due to overhunting in the mid-20th century.

Hybrid offspring of Hawaiian Ducks seem to be less well-adapted to native habitat, and utilizing them in reintroduction projects apparently reduces success.

In summary, the problems of Mallards " hybridizing away " relatives is more a consequence of local ducks declining than of Mallards spreading ; allopatric speciation and isolating behaviour have produced today's diversity of Mallard-like ducks despite the fact that in most if not all of these populations, hybridization must have occurred to some extent.