Identification: a small crow with black plumage and gray on the back of the head.

RAVEN

Identification: a large (2 foot), all-black bird similar to a crow but much bulkier..

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

Behavioral Expression: Black-billed Magpies sometimes court and form pair-bonds with birds of the same sex. Partners include adult males with younger or juvenile males (less than one year old), or else two females or two males of the same age, usually juveniles but also sometimes two adult males. A typical homosexual courtship—for example, between two males—begins with one bird ritually BEGGING the other by crouching in front of him and flapping or quivering his wings while uttering a begging call. The other male responds by hopping in tight circles around him, fluffing up his white feathers and flicking his wings; he may also BABBLE-SING, a varied combination of warbling, chattering, and yelping notes. The circling male often adopts a TILTING posture, in which he points his head and tail sideways toward the other male. If the male he is courting flies off, a courtship pursuit known as CHASE-HOPPING may develop, in which one male follows the other while alternately flying and hopping. Sometimes the two birds also HOVER-FLY, one in front of the other, using a rhythmic, undulating flight pattern. The same series of behaviors is seen in courtships between females (as well as in heterosexual interactions). Homosexual courtship sessions can last for up to half an hour. After courting, two birds of the same sex may form a pair-bond. Paired birds stay near each other, follow one another, and often cooperate in evicting intruders from their territory. They also frequently sit close together and preen one another or engage in mutual BILLING, in which they affectionately nibble at each other’s beak. Sometimes, homosexual mates also pull or nibble on the same leaf or twig and pass it back and forth between them; this is known as TUGGING. Same-sex pair-bonds are generally of shorter duration than adult heterosexual bonds and last from a few days to several months. However, adult males sometimes form longer-lasting homosexual pairs, and the two birds may even build a nest together (which typically takes five to seven weeks to construct).

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.

Homosexual courtship in Black-billed Magpies: “tilting” (left) and “begging”

Female homosexual pairs also occasionally occur in Ravens, including incestuous bonds between yearling sisters. Birds in same-sex pairs engage in intense courtship activity similar to heterosexual pairs, such as mutual preening and courtship-feeding.

Frequency: Among Jackdaws in the wild, approximately 5 percent of trios include bonding between the two female partners, while about 10 percent of widowed females form homosexual pairs. Overall, though, same-sex bonds probably represent no more than 1 percent of all pairs/trios. Homosexual activity occurs sporadically in Black-billed Magpies and Ravens as well: about 1 percent of nesting pairs of Magpies, for example, consist of two males. Although homosexual copulations between Magpies have not yet been recorded, heterosexual matings are also infrequently observed (only 9 male-female copulations, for example, were recorded during one 300—hour study period).

Orientation: Homosexual behavior is most prevalent among younger Black-billed Magpies, some of whom also court members of the opposite sex; many of these birds go on to form heterosexual attachments when they become adults, but most are nonbreeders during the time of their same-sex activities. Some adult males, however, continue to court younger males or pair with other adult males. In Jackdaws and Ravens many different forms of bisexuality occur. Some females are simultaneously bonded to both males and females, and such trios may develop out of either an initial heterosexual or homosexual pair-bond. Some females are sequentially bisexual, developing same-sex bonds only after losing their male partners. However, those Jackdaw females who enter into homosexual pairs as nonbreeders may have no prior (and perhaps no subsequent) heterosexual experience.

Nonreproductive and Alternative Heterosexualities

Black-billed Magpies and Jackdaws participate in a number of nonprocreative heterosexual activities. Birds sometimes copulate long after fertilization has taken place—even during incubation or chick-rearing—while courtship and mounting may occur well in advance of the breeding season in Magpies. In both species, birds form pair-bonds as juveniles, long before they are able to breed. Several alternatives to the monogamous pair and nuclear family are also to be found in these species of Crows. In Black-billed Magpies, for example, courtship and copulations with birds outside of the pair-bond can be more frequent than within-pair matings. In addition, some pairs get divorced: about half of all males and just under two-thirds of females change mates, and some may pair with up to three different partners over the course of their lives. Other Magpies, however, do remain in lifelong, faithful pair-bonds. About 6—10 percent of adult Jackdaw pairs, and a third of all juvenile pairs, get divorced. Polygamous trios also sometimes develop in Magpies (1—2 percent of bonds), but are fairly common in Jackdaws, comprising about 14 percent of all bonds. These usually result from an unpaired female joining an existing male-female pair; unlike the bisexual trios described above, she usually bonds only with the male of the pair, not the female. Occasionally, she may oust the former female and start a new family with the male; frequently, however, the newcomer female does not breed even if she remains in the trio for several years.

Nonbreeding couples also occur in Jackdaws and Ravens, as well as a significant population of single, nonreproducing birds. The latter are found in Magpies as well, where they make up 20—60 percent of the population and may be solitary or form their own flocks. In addition, about half of all Magpies that survive to adulthood leave no descendants (even if they try to breed). Some nonbreeding Jackdaw pairs—or couples who have tried unsuccessfully to breed—end up harassing breeding pairs by invading their nests, fighting with them, and even attacking and occasionally killing their young with vicious pecks. Nearly a third of all breeding pairs in some populations are harassed in this way. Cannibalism of young and eggs by neighboring breeding pairs also sometimes occurs in Jackdaws. Magpies and Ravens occasionally adopt unrelated youngsters when they pair with a bird that has lost its mate. Magpie families also sometimes foster-parent chicks as a result of the extraordinary phenomenon of “egg transfer”: in some populations, up to 8 percent of nests contain a foreign Magpie egg, but not as a result of being laid there. Rather, another Magpie has physically carried its own egg in its beak to the new nest, placing it there to hatch and be raised by the host parents. Stealing and cannibalism of young or eggs has also been reported among Black-billed Magpies: about 7 percent of nests are robbed by other Magpies. In addition, at least 30 percent of nestlings die of starvation as a result of competition from their siblings, or from direct attacks or cannibalism by their nest-mates.

Other Species

Homosexual courtship occurs in some species of Jays (closely related to Crows), so far observed only in captivity. Male Gray-breasted or Mexican Jays (Aphelocoma ultramarina ), a species found in the American Southwest and Mexico, have been seen COURTSHIP-FEEDING younger males in mixed-sex groups. This behavior—also part of heterosexual courtships—involves one male offering the other a food item; the latter accepts it while quivering his wings, crouching, and uttering a low kwa kwa kwa call. After eating the food or storing it in a cache, he may follow the other male to repeat the episode. Female San Bias Jays (Cyanocorax san-blasianus ) of Mexico have been known to court other females in same-sex groups in captivity, using the SOTTO VOCE SONG DISPLAY. While making soft, throaty vocalizations, one female sidles up to the other on a perch with her tail raised and belly feathers fluffed.

BIRDS OF PARADISE, BOWERBIRDS, AND OTHERS

RAGGIANA’S BIRD OF PARADISE

IDENTIFICATION: A crow-sized bird; male has a bright yellow head, an iridescent green throat, and a long “tail” of orange flank feathers; female has a duller yellow head and brown facial mask and no orange “tail.”