Biological Exuberance: Animal Homosexuality and Natural Diversity

IDENTIFICATION: A medium-sized deer typically with a grayish brown coat and white underparts, and antlers in both sexes. DISTRIBUTION: Circumboreal, induding northern North America and Eurasia. HABITAT: Tundra, taiga, coniferous forest. STUDY AREA: Badger, Newfoundland, Canada; subspecies R.t caribou, the Woodland Caribou, and R.t. groenlandicus, the Barren-Ground Caribou.

MOOSE

IDENTIFICATION : The largest species of deer (weighing up to 1,300 pounds); has slender legs, a pendulous nose, and (in males) prominent palmate antlers and a dewlap or “bell” beneath the throat. DISTRIBUTION: Northern Eurasia and North America. HABITAT: Moist woodland. STUDY AREAS: Jackson Hole, Wyoming; Kenai Peninsula, Alaska; Badger, Newfoundland; Wells Gray Provincial Park, British Columbia, Canada; subspecies A.a. shirasi, the Wyoming Moose; A.a. gigas, A.a. ameacana, and A.a. andersoni.

Social Organization

Caribou are highly gregarious, sometimes forming herds of tens or even hundreds of thousands of animals (although most groups contain 40–400 animals). They typically associate in all-male, mother-calf, and juvenile/adolescent bands. Moose, on the other hand, are more solitary, although they form aggregations of up to several dozen animals during the fall rutting period. Groups of bulls and cosexual herds may also coalesce after the mating season. In both species, animals mate with multiple partners rather than forming long-term heterosexual bonds, and males do not participate in raising their young (i.e., they have a polygamous mating system).

Description

Behavioral Expression: Caribou and Moose occasionally participate in a variety of same-sex courtship and sexual activities. Male Moose, for example, sometimes direct courtship behaviors toward other males, including sniffing the anal and genital region, and approaching another bull while making the characteristic rutting sound, the CROAK (a grunting call that combines a deep, resonant syllable with a popping or suction noise). Younger male Caribou may also court other males by making a similar sound, sometimes known as SLURPING or VACUUM LICKING, in which the animal flicks or smacks his tongue against the upper palate while approaching the other male with his head outstretched. Female Caribou sometimes mount each other, as do younger males, while yearling male Moose have been observed trying to mount adult bulls. In addition, bull Moose sometimes associate with younger male companions —known as SATELLITES—that travel together in pairs or small groups, usually outside the breeding season. Another homosexual activity among males in both Moose and Caribou is antler rubbing. In these two species (as in several other types of Deer), antlers are highly sensitive organs and genuine erotic zones, and males may become sexually aroused when they rub their antlers together. Among Moose, this is done rather gently as a sort of “play-fighting” (the antlers may still have their velvet covering), while Caribou males rattle their antlers against each other when they are free of velvet.

A male Caribou (left) courting another male by “vacuum licking”

Several types of gender-mixing occasionally occur in Moose, often involving unusual antler configurations. Intersexed males lacking a scrotum or testes sometimes develop what are known as VELERICORN antlers, which are covered in velvet and festooned with various ridges and knobs; such antlers are permanent, unlike regular antlers, which are shed and regrown each season. Other males—sometimes known as PERUKES—have elaborate, misshapen antlers covered with baroque nodule-like growths. Occasionally, females develop antlers, which may be single; spiked (without branches); covered in velvet; or lacking the flat, palmated structure typical of male Moose antlers. Caribou are the only deer in which females regularly sport antlers: depending on the population, anywhere from 8–95 percent of females may be antlered.

Frequency: Homosexual activity occurs only sporadically in Moose and Caribou. About a quarter of all male Moose associate together in pairs during at least part of the year.

Orientation: Adult animals that participate in homosexual activities in these two species are, in all likelihood, predominantly heterosexual, albeit with some bisexual capability. Some younger animals—especially among male Moose—may tend toward a less heterosexually oriented bisexuality, since many do not fully participate in heterosexual mating.

Nonreproductive and Alternative Heterosexualities

In both Moose and Caribou, many animals do not procreate. Caribou males are physiologically capable of breeding when they are a year old, yet most do not mate until they are at least four years old since they cannot successfully compete with the older bucks; a similar pattern is found in Moose. Among Caribou, females without calves may associate with a breeding female as an “assistant mother,” and some even try to “kidnap” or lure a calf away from its biological mother. During severe food shortages, pregnant Caribou females may terminate the breeding process by reabsorbing their embryos, since they would not be able to successfully raise their calves under such conditions. Approximately 8 percent of the male Caribou population consists of older (10+ years), postreproductive males that do not participate in breeding. However, many stags never reach this age, since the life expectancy of males is considerably shorter than that of females, at least in part because of the stresses associated with breeding. In Moose, breeding is also a taxing activity for bulls, who fast completely during the rutting period. Mating can also be a traumatic activity for females: because males in these two species are considerably larger, females often suffer injuries from copulation, sometimes literally collapsing under the weight of a male mounting them. As a result, female Caribou often strongly resist mating attempts and struggle to escape (less than two- thirds of matings are completed), while males may strike them with their antlers to make them submit to mounting. Females, in turn, may use their own antlers to fight back. Female Moose often strike males with their front hooves during the rutting season as well, and are capable of inflicting serious injury. In both species, there is significant segregation of the sexes outside of the breeding season: in Moose, for example, only 10–20 percent of winter groups are cosexual.

Moose and Caribou also participate in a variety of nonreproductive sexual behaviors. Males of both species sometimes try to mount calves, and female Caribou sometimes REVERSE mount males. Heterosexual interactions often involve oral-genital contact—male Moose and Caribou lick the female’s vulva, while female Caribou sometimes lick the male’s penis. About 45 percent of heterosexual mounts in Moose do not involve penetration or ejaculation, and males sometimes mount females up to 14 times in a sequence. In addition, both male Moose and Caribou “masturbate” by rubbing their antlers against vegetation, which often results in sexual stimulation (including erection of the penis and possibly ejaculation).

Sources

*asterisked references discuss homosexuality/transgender

Altmann, M. (1959) “Group Dynamics in Wyoming Moose During the Rutting Season.” Journal of Mammalogy 40:420–24.

*Bergerud, A. T. (1974) “Rutting Behavior of Newfoundland Caribou.” In V. Geist and F. Walther, eds., The Behavior of Ungulates and Its Relation to Management, vol. 1, pp. 395–435. IUCN Publication no. 24. Morges, Switzerland: International Union for Conservation of Nature and Natural Resources.

*Bubenik, A. B., G. A. Bubenik, and D. G. Larsen (1990) “Velericorn Antlers on a Mature Male Moose (Alces a. gigas).” Alces 26:115–28.

Bubenik, A. B., and H. R. Timmerman (1982) “Spermatogenesis of the Taiga-Moose—a Pilot Study.” Alces 18:54–93.

*Denniston, R. H., II (1956) “Ecology, Behavior, and Population Dynamics of the Wyoming or Rocky Mountain Moose, Alces alces shirasi.” Zoologica 41: 105–18.