Breeding
Their breeding habitat is alkaline marshes, acid bogs, lakes, ponds, rivers, marshes, brackish marshes, and the margins of estuaries and other aquatic environments in northern Saskatchewan, Manitoba, across Ontario and Quebec as well as the Atlantic Canadian Provinces, including the Great Lakes, and the Adirondacks in the United States. Female Black Ducks lay an average of 9 eggs.
Black Ducks interbreed regularly and extensively with Mallard ducks, to which they are closely related. Some authorities even consider the Black Duck to be a subspecies of the Mallard, not a separate species at all; this is in error as the extent of hybridization alone is not a valid means to delimitate Anas species.
It has been proposed that in the past, Black Ducks and Mallards were formerly separated by habitat preference, with the dark-plumage Black Ducks having a selective advantage in shaded forest pools in eastern North America, and the lighter plumage Mallards in the brighter, more open prairie and plains lakes. In recent times, according to this view, deforestation in the east, and tree planting on the plains, has broken down this habitat separation, leading to the high levels of hybridization now observed. However, rates of past hybridization are unknown in this and most other avian hybrid zones, and it is merely presumed in the case of the American Black Duck that past rates were lower than those seen today. It should also be pointed out that many avian hybrid zones are known to be stable and longstanding despite the occurrence of extensive interbreeding. At any rate, American Black Ducks and local Mallards are now very hard to distinguish by means of microsatellite comparisons, even if many specimens are sampled Contrary to this study's claims, the question whether the American haplotypes are an original Mallard lineage is far from resolved. Their statement, "orthern black ducks are now no more distinct from mallards than their southern conspecifics" of course only holds true in regard to the molecular markers tested. As birds indistinguishable according to the set of microsatellite markers still can look different, there are other genetic differences that were simply not tested in the study.
The hybrids cannot be readily distinguished in the field and consequently, much of the species' hybridization dynamics remains unknown. It has been revealed in captivity studies, however, that the hybrids follow Haldane's Rule, with hybrid females often dying before they reach sexual maturity this underscores the case for the American Black Duck being a distinct species.
This species is partially migratory and many winter in the east-central United States, especially coastal areas; some remain year-round in the Great Lakes region. These birds feed by dabbling in shallow water, and grazing on land. They mainly eat plants, but also some molluscs and aquatic insects. The eggs are a greenish buff color. They lay from 6–14 eggs, and hatch in an average of 30 days.
This duck is a rare vagrant to Great Britain, where, over the years, several birds have settled in and bred with the local Mallards. The resulting hybrids can present considerable identification difficulties.
Read more about this topic: American Black Duck
Famous quotes containing the word breeding:
“The breeding we give young people is ordinarily but an additional self-love, by which we make them have a better opinion of themselves.”
—François, Duc De La Rochefoucauld (1613–1680)
“A man’s own good breeding is his best security against other people’s ill-manners.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“Civility, which is a disposition to accommodate and oblige others, is essentially the same in every country; but good breeding, as it is called, which is the manner of exerting that disposition, is different in almost every country, and merely local; and every man of sense imitates and conforms to that local good breeding of the place which he is at.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)