Hormonal and sensory control of scent-marking in the desert woodrat (Neotoma lepida lepida).

Abstract

In Experiment 1, the marking behavior of adult male and female woodrats was tested in a neutral environment Males showed higher levels of ventral rubbing than females, whereas the reverse was true for the body-rolling response. In Experiment 2, the influence of testosterone propionate and estradiol-17 on scent-marking in female and male gonadectomized experimental animals was investigated. Animals were given a series of marking tests prior to and during social encounters with conspecifics. Ventral rubbing was found to be under androgenu control, and body rolling was partially under estrogenic control. In both sexes, high-dominance status and circulating testosterone were necessary for the occurrence of ventral rubbing during social encounters. In Experiment 3, the ventral rubbing of males in the cages of conspecifics was observed before and after social encounters with these animals. Before social encounters males showed higher levels of rubbing to conspecific odors than to neutral odors or to their own odors Alter social encounters males increased their ventral rubbing in cages of females but not in cages of males. In Experiment 4, males preferred to ventral rub in areas soiled with the odor of other males rather than those soiled by females but preferred to roll in areas soiled by females. Estrogen-primed females preferred to roll in areas soiled by males over those previously soiled by females.

Hormonal Influences on Territorial Marking Behavior

“…Marking frequency does not change with the estrous cycle or after ovariectomy (Maruniak, Owen, Bronson, & Desjardins, 1975). In contrast, ovariectomy virtually eliminates the low levels of urine-marking in female rats and the low levels of ventral-gland marking in female wood rats (Brown, 1977(Brown, , 1978Fleming & Tambosso, 1980). Testosterone implants (woodrats) or TP injections (rats) stimulate scent-marking in both these species, but ovarian steroids (estradiol implants in woodrats; EB, progesterone, or EB plus progesterone injections in rats) do not.…”

“…Often the frequency of scent-marking also shows large sex differences, again usually favoring the males. Male gerbils, woodrats, rabbits, hares, and antelope all have more prominent scent glands and scent mark more often than conspecific females (Fleming & Tambosso, 1980;Gilbert, 1974;Howe, 1977;Moy, 1970;Mykytowycz, 1965;Ralls, 1971;Schaller, 1967;.…”

“…Their secretions can be deposited passively (i.e., while the animal is involved in other activities, such as sand-bathing or walking through heavy brush), but are usually rubbed onto objects or the ground with special motor patterns (Mykytowycz, 1970;Ralls, 1971;Thiessen & Rice, 1976). Gerbils and woodrats, for example, press their bellies to the ground to deposit secretions from a ventral gland (Fleming & Tambosso, 1980;Howe, 1977;Thiessen, Wallace, & Yahr, 1973). Hamsters and water voles scent-mark with flank glands.…”

“…The gland and the behavior are apparently both controlled by gonadal androgens in males (Clarke, 1975;Fleming and Tambosso, 1980); however, as in other species, the extent to which hormones regulate scent-marking is constrained by social factors. Isolated males lacking sexual and aggressive experience obtain low marking scores, similar to those of females, although there is no reason to suspect that their testosterone secretion is impaired.…”

“…Suffice it to say that many researchers have systematically manipulated stimuli, many of which are hormone dependent, to which animals are exposed during scent-marking tests. (For the interested reader, a few examples from the literature already cited include Brown, 1977Brown, , 1978Epple, 1978Epple, , 1980Epple, , 1981Fleming & Tambosso, 1980;Hull et ai., 1973;Johnston, 1975aJohnston, ,b, 1977Johnston, , 1979Maruniak et ai., 1974;Maruniak, Owen, Bronson, & Desjardins, 1975;Maruniak, Darney, & Bronson, 1975;von Holst & Buergel-Goodwin, 1975. ) CONCLUSIONS Communication plays an important role in the control of aggression.…”