It’s spring, and a female duck swims across a pond with ducklings in tow. Some of the youngsters might not be her own. Wood Ducks and others may lay some of their eggs in other ducks’ nests — or in the nests of other kinds of ducks, like Common Mergansers and goldeneyes. Biologists call this nest parasitism or egg dumping. Perhaps it’s a kind of insurance against the loss of a nesting female’s own eggs or brood. Hooded Mergansers, like this one, are frequent recipients of eggs from other species. It’s a good bet that mother duck has at least one – and maybe more – foster ducklings.

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