Bruce Bagemihl - Biological Exuberance

Sometimes outright hostility erupts between males and females, including chasing and harassment, as well as actual aggression, violence, and injury (inflicted by males on females and, less commonly, by females on males). Attacks can be as brutal as they are commonplace. Female Savanna (Olive) Baboons, for instance, are liable to be attacked almost daily by males without provocation, and each female is severely wounded about once a year; injuries are sometimes fatal. Sexual coercion (i.e., punishment or intimidation by males of “uncooperative” females) as well as outright rape also occur in a wide variety of animals, occasionally involving “gangs” of males that attack and forcibly mate with females. 111Heterosexual rape is especially prevalent among birds such as ducks and gulls, but also occurs in mammals such as primates (e.g., Orang-utans, Rhesus Macaques), hoofed mammals (e.g., Bighorn Sheep), and marine mammals (Right Whales, and numerous seal species). In birds that form pair-bonds, rape usually involves mating attempts on females other than the male’s partner, but forced copulation within the pair-bond is not unknown, occurring, for example, in Silver Gulls, Lesser Scaup Ducks, and several other duck species.

Throughout the animal kingdom, heterosexual mating can be a dangerous and even lethal undertaking for females. Male Sea Otters often bite females on the nose during aquatic copulations, sometimes resulting in drowning or fatal infections; swarms of a dozen or more woodfrogs often try to mate with the same female, occasionally killing her in the process; female sharks of several species are routinely and severely bitten on the back during heterosexual courtship; while male mink may puncture the base of the female’s skull and brain with their teeth during mating. 112These are just a few examples of how heterosexual mating is often a destructive, rather than a procreative, act.

When most people think about animal families, they imagine a mother deer lovingly tending her fawns, or a father bear diligently protecting mother and babies. The realities of animal heterosexuality are a far cry from this romanticized view. More often than not, a mother deer viciously drives her yearlings away from the family group (when she hasn’t aborted her fetuses, that is) while father bear rarely has anything to do with his family—and when he does, it is often to kill and eat them. This section examines some of the stark realities of animal “family life,” beginning with a look at the many mechanisms that animals use to avoid having families altogether, by limiting reproduction and eliminating offspring.

In addition to infrequent copulation or mating during times when fertilization cannot occur, several other forms of “birth control”—i.e., ways of preventing pregnancy—occur in animals. 114In fact, more than 20 different strategies have been identified whereby females are able to limit, control, or prevent insemination. The widespread occurrence of these phenomena throughout the animal world has led one scientist to conclude that “copulation… seldom leads directly and inevitably to fertilization.” 115Some female birds such as brown boobies defecate during mating rather than performing the customary genital contractions, thereby preventing insemination, while females of a number of insect, bird, and mammal species actively eject semen after copulating. 116Among mammals, vaginal or copulatory plugs (sometimes also known as chastity plugs) are found in a number of species. Gelatinous barriers form (or are deposited) in the female’s reproductive tract in several different kinds of rodents, bats, insectivores, and wild pigs, as well as in some primates and dolphins. Although their function is not fully understood, it appears that plugs often serve to prevent insemination. In many species a male leaves a copulatory plug in the female following mating (or the semen simply coagulates to form the plug) so that other males will not be able to fertilize her. In Squirrel Monkeys and some bats, hedgehogs, and opossums, however, the female herself produces the plug (often from sloughed vaginal cells), probably to control or prevent inseminations by males. In addition, female squirrels sometimes entirely remove copulatory plugs—which contain all the semen deposited by a male—thereby effectively preventing insemination from their most recent mating. 117Finally, scientists recently discovered that female Common Chimpanzees employ an extraordinary form of birth control: nipple stimulation. As in a number of other mammals, the regular reproductive cycles of female Chimps are inhibited or interrupted while they are suckling infants (known as lactational amenorrhea). Some females without infants have learned that by stimulating their own nipples they can effectively mimic this physiological effect, thereby preventing themselves from conceiving even though they are not actually lactating. In some cases, Chimps have avoided pregnancy for as long as a decade by employing this ingenious “contraceptive” technique. 118

Following conception, pregnancy can be blocked (the fertilized egg does not implant, a phenomenon found in many rodents, where it is known as the Bruce effect). 119Embryos can also kill each other by puncturing or strangulation (Pronghorns) or by actively devouring one another inside the uterus (sand sharks, some salamanders). 120Embryos may also be “eliminated” because the mother has too few nipples to accommodate all of them (some marsupials such as Northern Quolls), while embryos of many hoofed mammals are simply reabsorbed. 121Actual abortion occurs in many species, including primates (e.g., Hanuman Langurs, Pig-tailed Macaques, Savanna Baboons), marine mammals (Australian Sea Lions, other seals), hoofed mammals (feral Horses, White-tailed Deer), carnivores (Red Foxes), and numerous rodents and insectivores (wood rats, voles, coypus). Abortions may occur either spontaneously, or as a result of stress and harassment from males, or (in primates) possibly also from deliberate ingestion of abortion-inducing plants. Though usually a sporadic or isolated occurrence, abortions may be more commonplace in some species or populations. In California sea lions, for example, large numbers of females routinely abort their fetuses: hundreds of abortions take place each year on some breeding grounds, often as long as four months in advance of the usual birthing period. 122Many birds and other species that lay eggs practice the equivalent of “abortion”—that is, the termination of an embryo’s development—in the form of egg destruction (also known as ovicide), ejection of eggs from the nest, and/or clutch abandonment. 123

Following birth or hatching, many animals employ strategies of direct or indirect killing to “eliminate” offspring. Infanticide or direct killing of young is a widespread phenomenon in the animal kingdom, reported in all major animal groups. 124It is also a decidedly heterosexual behavior, often revolving around the creation of new breeding “opportunities.” In one common form of infanticide, for instance, a male kills youngsters so that he can mate with their mother and sire his own young. 125In another type of infanticide, females kills their own or related offspring—in black-tailed prairie dogs, for example, almost 40 percent of all litters suffer partial or complete loss to infanticide by females. 126Cannibalistic infanticide also occurs, in which young animals are not only killed but also eaten. 127Offspring are sometimes subjected to neglect and abuse as well, ranging from “absentee” parents who fail to incubate their eggs or properly attend to their youngsters (e.g., storm petrels, Oystercatchers, King Penguins) all the way to abandonment, physical brutality, and/or sexual violence inflicted on youngsters (e.g., Hanuman Langurs, Northern Elephant Seals, Ring-billed Gulls), sometimes resulting in death. 128In many bird species, the size of families is regulated through a combination of factors. Parents frequently control the sequence of egg laying and hatching so that some offspring routinely perish (usually the last egg to be laid or hatched). In other cases “surplus” or extra young are produced as a “backup” strategy and usually end up fighting and killing each other (a phenomenon sometimes known as siblicide or cainism). 129