Brood reduction

rdf:langString Brood reduction

rdf:langString Brood reduction occurs when the number of nestlings in a birds brood is reduced, usually because there is a limited amount of resources available. It can occur directly via infanticide, or indirectly via competition over resources between siblings. Avian parents often produce more offspring than they can care for, resulting in the death of some of the nestlings. Brood reduction was originally described by David Lack in his brood-reduction hypothesis to explain the existence of hatching asynchrony in many bird species. Hatching asynchrony occurs when the parents start incubating their eggs before all of them have been laid. If resources are limited, it benefits the parents to allow brood reduction, because it reduces the amount of work they must do and increases their chances of surviving and reproducing again in future years. Brood reduction has been observed in many avian species including seabirds such as black-legged kittiwakes, birds of prey such as Swainson's hawk and several eagle species, and songbirds including black-billed magpies and house wrens.