page_title: Corvidae
section_title: Reproduction
hierarchical_section_title: Corvidae / Behaviour / Reproduction
caption_attribution_description: English: A pair of Gray Jays feeding their nestling. Algonquin Park, Ontario, Canada.
context_page_description: Corvidae is a cosmopolitan family of oscine passerine birds that contains the crows, ravens, rooks, jackdaws, jays, magpies, treepies, choughs, and nutcrackers. In common English, they are known as the crow family, or, more technically, corvids. Over 120 species are described. The genus Corvus, including the jackdaws, crows, rooks, and ravens, makes up over a third of the entire family. Corvids are the largest passerines.
  Corvids display remarkable intelligence for animals of their size and are among the most intelligent birds thus far studied. Specifically, members of the family have demonstrated self-awareness in mirror tests and tool-making ability, skills which until recently were thought to be possessed only by humans and a few other higher mammals. Their total brain-to-body mass ratio is equal to that of non-human great apes and cetaceans, and only slightly lower than that of humans.
  They are medium to large in size, with strong feet and bills, rictal bristles, and a single moult each year. Corvids are found worldwide except for the tip of South America and the polar ice caps.
context_section_description: Many species of corvid are territorial, protecting territories throughout the year or simply during the breeding season. In some cases territories may only be guarded during the day, with the pair joining off-territory roosts at night. Some corvids are well-known communal roosters. Some groups of roosting corvids can be very large, with a roost of 65,000 rooks counted in Scotland. Some, including the rook and the jackdaw, are also communal nesters.
  The partner bond in corvids is extremely strong and even lifelong in some species. This monogamous lifestyle, however, can still contain extra-pair copulations. Males and females build large nests together in trees or on ledges; jackdaws are known to breed in buildings and in rabbit warrens. The male will also feed the female during incubation. The nests are constructed of a mass of bulky twigs lined with grass and bark. Corvids can lay between 3 and 10 eggs, typically ranging between 4 and 7. The eggs are usually greenish in colour with brown blotches. Once hatched, the young remain in the nests for up to 6–10 weeks depending on the species.
  Corvids use several different forms of parental care, including biparental care and cooperative breeding. Cooperative breeding takes place when parents are helped in raising their offspring, usually by relatives but also sometimes by non-related adults. Such helpers at the nest in most cooperatively breeding birds are males, while females join other groups. White-throated magpie-jays are cooperatively breeding corvids where the helpers are mostly female.
caption: A Canada jay pair feeding their chicks.
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