Biological Exuberance: Animal Homosexuality and Natural Diversity

latter is mounting a female. Male Bush Dogs have also been observed mounting each other, often accompanied by playful nipping of the legs or hindquarters.

Frequency: In captivity, homosexual mounting in Red Foxes and Wolves occurs frequently when the breeding female is in heat. In Bush Dogs, mounting between males is less common. The prevalence of these behaviors in the wild is not known.

Orientation: Many female Red Foxes that mount other females may be exclusively same-sex oriented, since such younger or lower-ranking individuals usually do not mate with males. For some females, this homosexual orientation may be longlasting—perhaps even continuing for a female’s entire life—since as many as 50–70 percent of vixens never leave their home groups to begin breeding on their own. Male Wolves that mount each other are bisexual, also showing sexual interest in females. However, their heterosexual activity is limited to the highest-ranking breeding female: males routinely ignore lower-ranking females in favor of homosexual activity.

A female Red Fox mounting another female

Nonreproductive and Alternative Heterosexualities

In all three of these wild dog species, reproductive suppression is a prominent feature of the social system. For example, only a fraction of female Red Foxes reproduce—a third or more of all vixens (depending on the population) are non-breeders, and in some areas as many as 95 percent of adult females do not reproduce. There are multiple mechanisms for this “birth control.” In some cases, nonbreeding females simply do not mate, or else they fail to come into heat (a similar phenomenon occurs in Bush Dogs). In other cases, females become pregnant, but routinely abort their fetuses or abandon their young once they are born. Neglect or abuse of pups (leading to their death) has been documented in both Red Foxes and Bush Dogs, as well as cannibalism (in Red Foxes). In Wolves, the highest-ranking individuals (especially males) often prevent other animals from mating by intruding or attacking them directly; as many as a quarter of all mounts may be interrupted this way. In other cases, Wolves simply show no sexual interest in the opposite sex; these and other factors function to curtail reproduction in 40–80 percent of all packs. Breeding may also be inhibited by an incest taboo when a pack comes to consist entirely of closely related individuals (usually siblings). However, mother-son and brother-sister matings have occasionally been observed, and some packs may be highly inbred. In both Red Foxes and Wolves (and to a lesser extent, Bush Dogs), nonbreeding animals sometimes help the breeding female raise her young, including feeding, guarding, and “baby-sitting” them. There are even cases of a female Red Fox adopting an entire litter after their biological mother has died or been killed. However, some nonbreeding Red Foxes do not contribute any such care, and there is actually some evidence that more offspring may be successfully reared when there are fewer such “helpers” present in the group. Nonbreeding lone Wolves that do not act as helpers may constitute as much as 28 percent of some populations.

In addition to patterns of reproductive suppression, a number of nonreproductive heterosexual activities also occur in these canids. About 8 percent of female Red Foxes mate outside of the breeding period (this practice occurs in Wolves as well). Because males also have a sexual cycle ensuring that they cannot produce sperm during this time, such matings are definitively nonprocreative. About half of all heterosexual mounts in Wolves do not involve thrusting, penetration, or ejaculation; female Wolves also sometimes mount and thrust against males (REVERSE mounting). When mating does occur in Wolves and Red Foxes, individuals often engage in multiple copulations (i.e., more than the number of times simply required for fertilization). These often involve “copulatory ties” that keep the partners joined at the genitals for long periods. Heterosexual relations are sometimes fraught with difficulty, for example when female Red Foxes aggressively gape at males trying to mount them, or when both male and female Wolves display indifference or aggression toward animals trying to mate with them. In fact, one study showed that less than 3 percent of all heterosexual courtships in Wolves actually result in copulation.

Other Species

Several forms of intersexuality or transgender occasionally occur in Raccoon Dogs (Nyctereutes procyonoides). Some individuals, for example, combine female genitals with testes, while others have a mosaic chromosome pattern that combines a male pattern (XY) with a joint male-female pattern (XXY).

Sources

*asterisked references discuss homosexuality/transgender

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