Rabbits: The Animal Answer Guide

6 Reproduction and Development of Rabbits

How do rabbits reproduce? You’ve probably heard the simile “mad as a March hare” and are familiar with the March Hare character of Alice in Wonderland. A similar expression dates to around 1500, “Thanne they begyn to swere and to stare, And be as braynles as a Marshe hare.” The allusion is to the mating behavior of European hares, which if not mad, certainly looks madcap. During the breeding season, which extends before and well past March in most areas, the normally secretive hares engage in extended chases, wild leaps, circling, and boxing. Boxing was once thought to be male-on-male aggression, but more often it is a pursued female that punches her suitor because she is not yet ready to copulate. In a typical sequence when a female is in estrus, a male approaches her from behind, sniffs her rear end, mounts, and they copulate. Copulation is short, about 10 seconds or so, after which the male dismounts and the female moves away. Before and during her period of receptivity , a dominant male guards his mate by chasing away subordinates that approach her, but a males’ interest in a female lasts only until the end of her short estrus, which appears to end in less than a day. Courtship and mating is fairly similar in jackrabbits. During the breeding season, male jackrabbits search their home ranges for females. When a male approaches a female, she either boxes him away or rough courtship ensues. Either may begin jumping in the air while the other runs underneath . The jumper often squirts urine on the “jumpee,” a behavior called enurination. This may sound disgusting, but in most mammals urine contains useful information: In European rabbits and likely all lagomorphs, Chapter 6 Reproduction and Development of Rabbits 111 112 Rabbits: The Animal Answer Guide chemicals in the urine or associated glands reveal the urinator’s sex, dominance status, and reproductive state (see “Do rabbits talk?” in chapter 4). Next comes a chase, with the pursuing male trying to mount the female, which aggressively rebuffs the male until their interactions stimulate her to receptivity. Finally, after 5 to 20 minutes of courtship, she permits copulation , which lasts only a few seconds. Thereafter she will no longer tolerate the male’s advances, although she may copulate again later. One or more males may be involved in chases of a single female, leading to aggressive charges among them that probably establish dominance. It is also similar in arctic hares, with one interesting twist. Males begin to perform an unusual display at the onset of the breeding season, as described by David Gray: “While the male stands with legs tensed, the long, slender, dark-coloured penis is uncoiled and stretched out along the belly, often extending out beyond the forelegs. This whip-like extension of the penis lasts about 1.5 seconds and is repeated up to 12 times in one bout.” With minor variations, chases by one or more males, fights in which the female is the aggressor, circling, and jumping with enurination followed by very short copulations are characteristic of the courtship behavior of all hares and rabbits in which it has been observed. Courtship and copulation in pikas appears to be a much more subdued affair: a male approaches a female, sniffs her genital area, and mounts. In all lagomorphs, estrus is always brief and, except for the first breeding cycle of the season, occurs just after—and sometimes just before in some hares—the birth of a litter. All female lagomorphs are believed to be induced ovulators, although this is not definitely known for all species. Induced, or reflex, ovulation means that the stimulation of courtship and copulation is required for a female to ovulate, unlike, for example, human females, who spontaneously ovulate about every 28 days even if no male is present. In European rabbits, ovulation occurs about 8 to 12 hours after copulation. Induced ovulation, which is probably the primitive condition of mammals, is likely an adaptation to ensure no opportunity to breed is missed, which contributes to lagomorphs’ generally high rates of reproduction. The flamboyant courtship behavior of rabbits and hares appears to be energetically expensive. It also seems risky. Rabbits engaged in courtship appear to be less vigilant and their behavior is far from secretive, exposing them to potential predators. Why, then, do they do it? It is possible that the strenuous courtship of rabbits and hares is related to female mate choice. A variety of female...