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BLACK-BILLED MAGPIE
IDENTIFICATION: A pigeon-sized, crowlike bird with striking iridescent, black-and-white plumage and a long, greenish purple tail. DISTRIBUTION: Eurasia, North Africa, western North America. HABITAT: Woodland, scrub, grassland, savanna. STUDY AREAS: Haren, the Netherlands; University of Groningen, the Netherlands; subspecies
JACKDAW
IDENTIFICATION: A small crow with black plumage and gray on the back of the head. DISTRIBUTION: Eurasia, North Africa. HABITAT: Forest, grassland, farmland. STUDY AREAS: Haren, the Netherlands; Max-Planck Institute; subspecies
RAVEN
IDENTIFICATION: A large (2 foot), all-black bird similar to a crow but much bulkier. DISTRIBUTION: Eurasia, North America. HABITAT: Varied, including forest, plains, desert. STUDY AREA: Max- Planck Institute; subspecies
Social Organization
All three of these Crow species are quite gregarious, often associating in flocks and communal roosts. Individuals generally form long-term mated pairs, and Jackdaws usually nest in colonies. Magpies sometimes participate in remarkable group displays known as CEREMONIAL GATHERINGS, noisy aggregations that may be related to territory acquisition.
Description
Female Jackdaws occasionally develop pair-bonds with other females. In some cases, an older female pairs with a younger one, and the two build a nest together even though the juvenile bird is too young to lay eggs. Later, they might construct a unique “double nest” consisting of two adjacent cups and lay infertile eggs in both cups. Sometimes, a homosexual pair is joined by a male, who may bond with one or both of the females to form a bisexual trio; in this way, the females can lay fertilized eggs. However, they are often unable to successfully care for their offspring, precisely because their bond to each other means that they try to stay together all the time. The two females incubate their eggs and brood their youngsters simultaneously, each sitting on one cup. When the male arrives for his shift, however, they both depart together, leaving the male to try to cover and protect both sets of eggs or nestlings at the same time (which he is usually unable to do). Sometimes, a bi-sexual trio forms when a female joins a heterosexual pair and develops a strong bond with the female partner. The two females engage in courtship and pair-bonding activities such as mutual preening or COURTSHIP-FEEDING, in which one partner begs the other by crouching, fluttering her wings, and quivering her tail. Both females might mate with the male and lay fertile eggs, although the bond between them can end up being stronger than the original heterosexual bond. In fact, in one case the female partners were not able to properly care for their young because the male denied the female “interloper” access to the nestlings. Homosexual bonds also sometimes develop between widowed and nonbreeding females. In these cases, females that lose their male partners during the breeding season may attract unmated females to pair with them; some of these widows are mothers, while others have no offspring. Unlike bisexual trios, which may remain together for years, these female bonds appear to be more transitory, usually lasting only for several weeks until the breeding season is over.