Monday, February 6, 2012

Hybrid American Black Ducks

On Sunday, Gerry H. and I searched for Black Ducks along the Cannon River in Faribault, Minnesota. In the photo above, the bird in the background is a fairly typical female Mallard. The middle duck is likewise also a Mallard. The bird in front, however, has a dark bill with an olive tip,typical of the American Black Duck. On the other hand, its tail feathers are broadly edge white, as you would expect on a Mallard. I suspect this bird is a hybrid Mallard and Black Duck.

Ornithologists once predicted the demise of the American Black Duck due to hybridization, as Mallards expanded out of the Grteat Plains into the eastern range of the Black Duck. This expansion was the result of habitat change and game farm releases in the east. Recently, however, Black Duck populations have increased. The two species prefer breeding true. Nevertheless, about 13% of harvested ducks are hybrids. The situation is confounded in that the offspring of hybrids breeding with non-hybirds are often look identical to either Mallards or Black Ducks, depending on with which species the hybrid mates (Longcore et al. 2000).

As you can see in the bottom photograph, the facial pattern on these hybrids is also odd. I find nothing identical in any of my field guides. Note also the hen Wood Duck behind the hybrid. Wood Ducks do not usually winter in this part of Minnesota.

No comments:

Post a Comment