Egg dumping is when a female lays her egg(s) in the nest of another bird, sometimes creating very large clutches, e.g., chickadees (also called conspecific brood parasitism). Also see obligate brood parasitism - e.g., cowbirds).
Sometimes the eggs from different females will have a slightly different shape or shading.
A dumping female may have been unable to obtain a nest site, lost a nest site, or had their own nesting attempt disrupted.
Cowbirds do not build their own nest, but instead parasitize the nests of other birds, taking out one egg and replacing it with their own
Nesting starling females will remove eggs deposited before they start to lay. Females who are laying parasitic eggs often take out one of the host eggs at the same time.
We celebrate the beautiful bluebird as a symbol of love, hope and happiness. - Larry Zeleny
