Parasitism is one of the many forms of symbiosis. In parasitism, one organism (called parasite) benefits at the expense of another organism usually of different species (called host). The parasite benefits at the expense of the host organism. A special form of parasitism is brood parasitism.
Brood parasitism is one in which the brood parasite leaves its young to an adoptive host. The latter would raise the young as if it were its own. Brood parasitism is demonstrated by certain species of birds, insects, and fish. One of the strategies used is brood mimicry. In essence, the eggs of the brood parasites mimic the host's and therefore the host would not detect eggs from another animal.
Brood parasitism is advantageous to the parasitic parents since they are relieved from having to rear their offspring and therefore they would have more time to engaging in other activities such as foraging and producing more offspring. As for the host parents, brood parasitism makes them invest greater time and effort in caring for additional offspring.