The resident pair of crows were sitting on an aerial this morning, and the individual to the right was cawing. I was waiting for it to call again camera in hand - I like the arched necks and up and down powerful movements of crows cawing. Instead, after a few moments, the other individual approached its mate and began preening. Carrion Crows, as other corvids, form long-term typically life-long partnerships, where both pair members share most of the duties. In fact, the only noticeable division of labour is incubating and feeding the young nestlings. Pairs remain and defend their territory together year round. Usually, the pair defend the same territory year after year. Pair cooperation takes the form of aggressive territory defence from other crows but also other species which might compete for food. Both members of the pair approach intruders and engage in duet cawing, apparently inciting each other to attack them. They will also carry out 'pincer tactics' in which each member of the pair try and face each other keeping the intruder in the middle. Carrion crow intruders are the main nest predators, with up to 50% of their nests being robbed by other crows, so it is important to keep them away from the territory.
More information
Bossema, I and R.F. Benus (1985) Territorial defence and intra-pair cooperation in the carrion crow
(Corvus corone). Behav Ecol Sociobiol. 16:99-104.
here.
Nicola S. Clayton, Nathan J. Emery, The social life of corvids, Current Biology, Volume 17, Issue 16, 21 August 2007, Pages R652-R656, ISSN 0960-9822, DOI: 10.1016/j.cub.2007.05.070.
here.
