(noun) The act of using metabolic (body) heat to keep eggs at an optimum temperature for healthy development and hatching. To incubate eggs, parent birds will sit on them, often bringing a brood patch into direct contact with the eggs. Eggs may be rotated periodically, and parent birds may take short breaks to preen, defecate or feed.
The length of the incubation period varies for each bird species and may last from just a few days to several weeks. Depending on the species, female birds may do the majority of the incubation or the task could be shared between both parent birds.