Reed Warbler

Warblers are popular songbirds in Europe and a cuckoo's favorite meal. A warbler mother is not only unlikely to spot imposters, but she will also keep feeding them even after they grow to be twice as big as her. Even better, when they remove her other eggs from the nest, she doesn't appear to notice. Not that reed warblers are kind or innocent; they have a cunning parenting tactic of their own.

Females of "low harem status" eat the eggs of their rivals since male reed warblers only ever support one nest, even though they may have spawned numerous. By placing plasticine eggs in mock nests and matching the peckmarks to the warbler, researchers were able to monitor this activity. In essence, a mistress rises up the support chain when she kills the first wife's children. Female immigrants who are single parents often try to profit from the killings. They are more likely to capture the male by constructing their nests close to a location of infanticide.

Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Acrocephalidae
Genus: Acrocephalus