Identification: a large (13—14 inch) sandpiper with streaked and spotted, dark brownish gray plumage; long and slightly upturned bill; greenish yellow legs.

REDSHANK

Identification: Slightly smaller than the Greenshank; plumage grayish brown, with black and dark brown streaks and spots; orange-red legs.

Social Organization

Outside of the mating season, Greenshanks congregate in flocks of 20—25 birds, while Redshanks are less social and may even be solitary. During the mating season, monogamous pairs are the predominant social unit, although a number of variations occur, including nonbreeding birds (see below).

Description

Behavioral Expression: In both Greenshanks and Redshanks, males sometimes court and copulate with each other. Homosexual courtship in Greenshanks involves spectacular aerial and ground displays, employing patterns also found in heterosexual courtship. One male may pursue another in a NUPTIAL FLIGHT, which starts out as a twisting, careening chase low over the ground, followed by a remarkable ascent of both birds to a great altitude. The two males swerve and turn in unison as they climb higher, sometimes disappearing completely into the clouds; the “sky dance” comes to a dramatic close as the males plummet back to earth in a steep dive. In the ground courtship display, two males bow, fan their tails, flap their wings, and utter deep growling calls or chip, quip, and too-hoo notes. This may lead to copulation (often performed on a stump or tree branch), in which one male flutters onto the back of another, lowering his body to make contact with the other while slowly flapping his wings. Homosexual copulation may be briefer than the corresponding heterosexual behavior. Males also sometimes try to copulate with other males that are calling in the treetops, and with males whose female mates are incubating eggs (in the latter cases, the female often makes a threatening or challenging call during the homosexual interaction). Male Greenshanks are also sometimes courted by male Green Sandpipers (Tringa ochropus), who approach them from behind with drooping wings and raised, partially fanned tails. The Sandpipers may also try to mount them; in contrast to within-species homosexual matings, male Greenshanks typically resist these sexual advances, shaking the Sandpipers off and violently pecking at them.

Homosexual courtship in Redshanks: one male pursuing another in a “ground chase”

Male Redshanks court other males with a GROUND CHASE (also used in heterosexual courtship). In this display, one male pursues another in a series of curves and circles, often running in a distinctive sideways motion—similar to that of a crab—with ruffled feathers and fanned tail. The pursuing male may give a “mate-call” consisting of repeated paired notes: tyoo-tyoo … tyoo-tyoo … , and both birds also sometimes make chipping or trilled calls during the chase. Occasionally one male also mounts the other and tries to copulate with him, although his advances are often rebuked by the other male (as also frequently happens in heterosexual copulations).

Frequency: Homosexual courtship and copulation probably occur only occasionally in Greenshanks and Redshanks, although no systematic long-term studies of their prevalence have yet been undertaken.

Orientation: In many cases, individuals that engage in same-sex activity are bisexual. Male Greenshanks and Redshanks court birds of both sexes, while male Greenshanks are sometimes heterosexually paired fathers when they participate in homosexual copulations with other males. In at least one case, a male Greenshank associated himself with a heterosexual pair and tried to copulate with both the male and the female (although it is not known whether that male himself was single or paired with a female).

Nonreproductive and Alternative Heterosexualities

Sexual behavior in these two Sandpipers often occurs at times when fertilization is not possible: male Greenshanks and Redshanks court and mate with females after eggs are laid, both during incubation and following the hatching of chicks. In addition, REVERSE mounting (in which the female mounts the male) also occurs in Greenshanks. Courtship and copulation with other species of sandpipers have been recorded, including lesser yellowlegs (Tringa flavipes) and Green Sandpipers (as noted above). A wide variety of alternative heterosexual mating and parenting arrangements are also found in these birds. Although both Greenshanks and Redshanks are primarily monogamous, males of both species sometimes court and mate with females other than their own mate. In addition, some individuals engage in a number of different polygamous mating arrangements: occasional trios occur in both species, composed of two females and a male. Both females may lay in the same nest, they may have separate nests, or one female may be nonbreeding. Redshanks sometimes also participate in serial polygamy, in which a male mates with a second female, or a female with a second male, after laying a clutch with a first mate. This involves deserting or “divorcing” the first mate, who then typically raises the young as a single parent. (In Greenshanks, another form of “single parenting” occasionally occurs, in which the male partner fails to help the female incubate the eggs, but remains paired with her.) In fact, about 11 percent of Redshanks (and up to a quarter of Greenshanks) change partners between or within breeding seasons (this is more common among males), and only about a third of all males and half of all females mate for life. Some birds may divorce and re-pair with up to four different partners during their lives. In a few cases, female Redshanks have even left their mate to pair with another male, only to return to their “ex” the following season and remain with him for many more years. Adoption or foster-parenting also takes place in Redshanks: females sometimes lay eggs in other females’ nests (who then raise all the chicks as their own), and Redshanks have even been seen taking care of chicks of other species of shorebirds, such as the avocet (Recurvirostra avosetta).

Some Greenshanks do not participate in breeding at all—about a quarter of all males, on average, do not procreate (and in some years this figure may be higher—nearly half of all males). This includes both single birds and those that are heterosexually paired but do not breed. Such nonbreeding pairs constitute an average of more than 15 percent of pairs, though in some years more than a third do not reproduce. Heterosexual relations may also be marked by unwillingness and aggression between the sexes: female Redshanks sometimes turn on males that are chasing them during courtship, staving off their advances with prolonged fights involving much pecking and scratching. Females of both species may also refuse to allow males to mount them: about a third of all Redshank heterosexual mating attempts, for example, are not completed due to female refusal.

BLACK-WINGED STILT