Daniel Q. Estep

Copulatory behavior and nest building behavior of wild house mice (Mus musculus)

The copulatory behavior and nest building behavior of wild house mice (Mus musculus) were examined in an attempt to study the effects of domestication on these behaviors. In the first experiment, 17 male and 17 female wild house mice were observed on a total of 68 tests of copulatory behavior, each carried to a satiety criterion of 90 min with no intromissions. The basic copulatory pattern was found to be identical to that of domesticated strains of house mice. However, the wild house mice appeared more extreme in certain of the quantitative aspects of copulatory behavior than most inbred strains. In the second experiment, 9 male and 10 female wild house mice and 10 male and 10 female C57BL/6J inbred house mice were tested for nest building behavior for 28 consecutive days. The nest building of wild house mice appeared similar to that of most domesticated house mice, although wild house mice used less cotton in building nests than did domesticated animals.

Copulatory behavior of golden hamsters: Effects on pregnancy

Two experiments were conducted to study the role of male copulatory behavior in initiating physiological responses necessary for pregnancy in female hamsters. In Experiment 1, it was found that copulation beyond the first ejaculatory series is critical to attainment of maximal probabilities of pregnancy. Whereas all females became pregnant when mated to a criterion of sexual satiety, only 20 percent were pregnant after one ejaculatory series. The relationship between increased copulatory stimulation and increased probability of pregnancy was further refined in Experiment 2. Females required more than 4 ejaculatory series to maximize the probability of pregnancy. Mounts without intromission had no effect. Neither parturition number of ova shed, nor little size appeared affected by amount of copulatory stimulation. A coadaptation between the copulatory pattern of the males and the response systems of the females of several rodent species appears to have evolved and to aid successful reproduction.

Food hoarding in muroid rodents.

The hoarding of food pellets was studied in 72 adult male muroid rodents of ten species; Mesocricetus auratus, Microtus ochrogaster, Microtus pennsylvanicus, Microtus montanus, Peromyscus californicus, P. eremicus, P. gossypinus, P. leucopus, Sigmodon hispidus, and Meriones unguiculatus. Seven Oryzomys palutris were also studied. Microtus and hamsters were the only species to show any appreciable hoarding. Six species were tested for the hoarding of sunflower seeds and corn kernels. Data were consistent with those on the hoarding of food pellets. Although information is incomplete, the ease of eliciting hoarding behavior in the laboratory appears roughly correlated with the tendency to hoard in the natural habitat. No other ecological correlates were apparent.

Variation of food hoarding with the estrous cycle of Syrian golden hamsters (Mesocricetus auratus)

Food hoarding was assessed in 16 adult female Syrian golden hamsters (Mesocricetus auratus) across the stages of the estrous cycle. Results show that food hoarding is depressed on the day of behavioral estrus but does not vary among the other days of the cycle. Decreases in food hoarding appear to be correlated with high levels of estrogen and progesterone. The data are consistent with the hypothesis that food hoarding, food intake, and weight gain are controlled either by the same mechanism or by similar mechanisms in some female rodents.

Copulatory behavior of Mongolian gerbils (Meriones unguiculatus)

Three experiments were conducted to provide a quantitative description of copulation in Mongolian gerbils (Meriones unguiculatus). The overall copulatory pattern of gerbils may be characterized as containing multiple intromissions, multiple ejaculations, no intravaginal thrusting, and no lock. Mean intromission frequencies failed to approach the exceptionally high values reported by previous workers. As the present data indicate that gerbils lie within rather than outside the range of performance of other muroid rodents, it is suggested that earlier hypotheses regarding unusual insensitivity of gerbil reproductive systems are unnecessary. Sexual satiety (30 min with no intromissions) was attained following a mean of 4.8–6.9 ejaculations. In contrast to most other species, males typically failed to complete the final ejaculatory series, even after many intromissions. Implications of this unusual mode of development of satiety are discussed.

Copulatory behaviour of cotton mice (Peromyscus gossypinus) and their reciprocal hybrids with white-footed mice (P. leucopus)

Abstract Cotton mice, Peromyscus gossypinus, display a copulatory pattern with no lock, no intravaginal thrusting, multiple ejaculations, and ejaculations occasionally occurring without prior intromissions. There are relatively few ejaculations per satiety test. Mice from two distinct populations were very similar with respect to basic motor patterns, quantitative measures, and associated behavioural patterns, suggesting that these patterns may be truly ‘species-typical’. The behaviour of the reciprocal hybrids between P. gossypinus and P. leucopus was found to resemble that of the parental species.