*———(1979b) “The Effects of Crowding on the Social Relationships and Behavior of the Dwarf Mongoose (Helogale undulata rufula).” Zeitschrift fur Tierpsychologie 49:317-29.
MARSUPIALS
EASTERN GRAY KANGAROO
IDENTIFICATION: A large (over 3 foot tall) kangaroo with a gray coat and a hair-covered muzzle. DISTRIBUTION: Eastern Australia. HABITAT: Open grasslands, forest, woodland. STUDY AREAS: Nadgee Nature Reserve, New South Wales, Australia; Cowan Field Station (Muogammarra Nature Reserve) of the University of New South Wales.
RED-NECKED WALLABY
IDENTIFICATION: A smaller kangaroo (21/2 feet tall) with a reddish brown wash on its neck. DISTRIBUTION: Coastal southeastern Australia. HABITAT: Forest, brush areas. STUDY AREAS: Michigan State University; Cowan Field Station (Muogammarra Nature Reserve) of the University of New South Wales; subspecies M.r. rulogriseus, Bennett’s Wallaby, and M.r. banksianus.
WHIPTAIL WALLABY
IDENTIFICATION: A light gray kangaroo standing up to 3 feet tall, with a white facial stripe and a long, slender tail. DISTRIBUTION: Northeastern Australia. HABITAT: Open forest, savanna. STUDY AREA: Near Bonalbo, New South Wales, Australia.
Social Organization
Eastern Gray Kangaroos often associate in large groups of 40–50 animals—sometimes known as MOBS. These comprise smaller cosexual groups of up to 15 
449 individuals, largely females and their young along with a few males. Some individuals are solitary. No pair-bonding occurs between males and females, and the mating system is polygamous or promiscuous. Whiptail Wallabies have a similar social organization, while Red-necked Wallabies are largely solitary (although groups of 8–30 animals may form at times).
Description
Behavioral Expression: Pair-bonds occasionally develop between female Eastern Gray Kangaroos, involving frequent mutual grooming in which the partners affectionately lick, nibble, and rake the fur on each other’s head and neck with their paws. Females in such associations also sometimes court and mount each other, and sexual activity may occur as well between females who are not necessarily bonded to one another. Significantly, heterosexual pair-bonds are not found in this species. In Red- necked Wallabies, females frequently mount each other: one female grabs the other from behind, wrapping her forearms around her partner’s abdomen and tucking her forepaws inside her partner’s thighs. This position resembles heterosexual copulation except that the mounting female is higher up on her partner’s body. Sexual activity is often accompanied by grooming, fur-nibbling and licking, pawing, and nosing of the partner. Males also sometimes mount one another, usually during play-fights in which the partners gently push, wrestle, or “box” one another with their forearms. Occasional affectionate activities such as grooming, licking, embracing, and touching also take place during these sessions, and sometimes one male will sniff or nuzzle the other’s scrotum. Courtship and sexual interactions between male Whiptail Wallabies involve TAIL-LASHING, a sinuous, sideways movement of the tail indicating sexual arousal, often accompanied by an erection. Mounting also occurs; one male sometimes presents his hindquarters to the other by crouching with his chest on the ground and raising his rump. Prior to mounting, a male frequently sniffs the other male’s scrotum (as in Red-necked Wallabies). Swept up in a courtship frenzy, males also sometimes embark on homosexual chases as a part of heterosexual interactions. A group of males will be pursuing a female in heat, furiously circling and dashing after her at breakneck speed; occasionally, other males on the sidelines are then drawn into the excitement of these wild chases—and they are as likely to pursue other males as they are the female.
In Eastern Gray Kangaroos, intersexual or hermaphrodite individuals also occur: some animals, for example, have both a penis and a pouch (the latter usually found only in females), mammary glands, and testes, all combined with body proportions that are generally intermediate between male and female. Chromosomally, these individuals have a mosaic of the female type (XX), the male type (XY), and a combined XXY pattern.
Frequency: Female homosexual mounting in Eastern Gray Kangaroos occurs sporadically: in one study of a wild population, for example, homosexual behavior was recorded eight times during four months of observation. It should be noted, however, that heterosexual mating is rarely observed as well: only one male-female mating was seen during that same time, while only three heterosexual copulations were recorded during a three-year study of Red-necked Wallabies. In captivity, mounting between female Red-necked Wallabies is quite common, but male homosexual activity is much less frequent. During play- fights between males, courtship and sexual behaviors occur roughly once every five hours of activity. Homosexual mounts between males account for about 1 percent of all mounting activity in Whiptail Wallabies.
Orientation: In captive groups of Eastern Gray Kangaroos (which included both sexes), four of six females formed same-sex pairs. Male Red-necked Wallabies may be sequentially bisexual during their lifetimes: sexual interactions during play-fighting are most common among adolescent males, while adults are probably more heterosexually oriented. Male Whiptail Wallabies that court or mount other males also interact sexually with females, i.e., they are simultaneously bisexual.
Nonreproductive and Alternative Heterosexualities
Female Red-necked Wallabies are often harassed by males trying to mate with them (similar behavior also occurs in Whiptail Wallabies). As many as seven males at a time may pursue a single female, and they may injure her while mating: females have been seen limping or with cuts on their backs after heterosexual copulations. Mating attempts may also be interrupted by other males charging the pair and trying to dislodge the mounting male. In this species, only about 18 percent of the males ever mate with females. Nonbreeding females also occur in Eastern Gray Kangaroos. In addition, females who are pregnant (including late-term), not in heat, or sexually immature also occasionally participate in heterosexual activity, and males also regularly masturbate by thrusting the erect penis into the paws. DELAYED IMPLANTATION is another notable feature of the reproductive cycle in these species.
Other Species
Homosexual mounting occurs in a number of other Kangaroo and Wallaby species: between females in Yellow-footed Rock Wallabies (Petrogale xanthopus), and between males in Western Gray Kangaroos (Macropus fuliginosus), Red Kangaroos (Macropus rufus), Agile Wallabies (Macropus agilis), Black-footed Rock Wallabies (Petrogale lateralis), and Swamp Wallabies (Wallabia bicolor). Transgendered or intersexual individuals of various types are also found in several species, including Red Kangaroos, Euros (Macropus robustus), Tammar Wallabies (Macropus eugenii), and Quokkas (Setonix brachyurus). Some of these individuals have female body proportions and external genitalia, female or combined male-female internal reproductive organs, a scrotum, and absence of a pouch and mammary glands. Others have male reproductive organs, intermediate or female body proportions, and a pouch and mammary glands.
Sources
*asterisked references discuss homosexuality/transgender
Coulson, G. (1997) “Repertoires of Social Behavior in Captive and Free-Ranging Gray Kangaroos, Macropus giganteus and Macropus fuliginosus (Marsupialia:
