Editing Corvidae (section)

===Reproduction===
[[File:Perisoreus canadensis feeding at nest.jpg|thumb|left|A [[Canada jay]] pair feeding their chicks. ]]
Many species of corvid are [[Territory (animal)|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 [[Rook (bird)|rooks]] counted in [[Scotland]].<ref name=Patterson/> 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.<ref name=Li/> Males and females build large nests together in trees or on ledges; jackdaws are known to breed in buildings and in rabbit [[Warren (burrow)|warrens]].<ref name="v&s2004" /> The male will also feed the female during incubation.<ref>[[Encyclopædia Britannica Online]]: [https://www.britannica.com/eb/article-9026450 Corvidae]. Free subscription required.</ref> 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 [[bi-parental care]] and [[cooperative breeding]].<ref>{{Cite journal|last=Cockburn|first=Andrew|date=7 June 2006|title=Prevalence of different modes of parental care in birds|journal=Proceedings of the Royal Society B: Biological Sciences|volume=273|issue=1592|pages=1375–1383|doi=10.1098/rspb.2005.3458|pmc=1560291|pmid=16777726}}</ref> [[Cooperative breeding]] takes place when parents are helped in raising their offspring, usually by relatives, but also sometimes by non-related adults.<ref>{{Cite journal|last=Bourke|first=Andrew F. G.|date=19 May 2014|title=Hamilton's rule and the causes of social evolution|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|volume=369|issue=1642|pages=20130362|doi=10.1098/rstb.2013.0362|issn=0962-8436|pmc=3982664|pmid=24686934}}</ref><ref>{{Cite journal|last=Riehl|first=Christina|date=7 December 2013|title=Evolutionary routes to non-kin cooperative breeding in birds|journal=Proceedings of the Royal Society B: Biological Sciences|volume=280|issue=1772|pages=20132245|doi=10.1098/rspb.2013.2245|pmc=3813341|pmid=24132311}}</ref> Such [[helpers at the nest]] in most cooperatively-breeding birds are males, while females join other groups. [[White-throated magpie-jay]]s are cooperatively-breeding corvids where the helpers are mostly female.