Cooperative breeding and altruistic behaviour in the mexican jay, Aphelocoma ultramarina

摘要: Summary The social organization of the Mexican jay is based on flocks typically eight to twenty individuals which tend be evenly dispersed through appropriate habitat. Most consist two or more breeding pairs adults plus a variable number non-breeding yearlings and adults. feeding young by all members flock was studied in field under natural conditions colour banding members. nestlings shared with 38 53 per cent visits parents remainder altruistic jays who were not they feeding. Parents showed significant preference for their own as long remained nest. after left nest also members, about 26 fed. no fledglings opposed other parents.