Gary F. Meunier

EVIDENCE OF LATERALITY IN THE LOWLAND GORILLA

The description of hand preference in the primates is at present sadly incomplete. In the lowland gorilla the consistency of the dextral preference across all tests is amazing and comparable to the human data. Similar analysis of the behavior of the orang-utan and a reexamination of the chimpanzee might present a coherent picture of homologous behaviours for the hominoidea.

Female discrimination of male dominance by urine odor cues in hamsters.

Female hamsters have been found to differentially respond to the odors of dominant as opposed to subordinate males. This study reexamined these responses in an olfactometer allowing the females to choose between urinary odors obtained from males differing in dominance status and clean air source. The behavior of the estrous females was consistent with previous research which indicated that such females exhibit a preference for stimuli obtained from dominant males. Contrary to previous findings in a two-choice apparatus, diestrous females failed to prefer the odors of subordinates. These females spent significantly more time in the area infused with unscented air. These data emphasize the importance of odor cues as they relate to male attractivity and possibly mate choice. They also underscore the need to allow animals to avoid conspecific odors in order to reduce the possibility of forcing animals into an unrealistic choice situation.

The ability of females to predict male status via urinary odors

In an earlier study, estrous female hamsters were found to prefer the urinary odors of dominant males. This study investigated whether estrous females would exhibit preferential responding to randomly chosen, socially naive males before dominance testing occurred. Estrous females were indeed found to exhibit such preferences. Such discriminative abilities are discussed with reference to adaptive mating strategies for females.

Responses to conspecifics' urine by the degu (Octodon degus)

In nature the degu has been observed to deposit and to investigate scents. This study employed a captive group of these animals to investigate their responses to conspecific urinary marks in a neutral arena. Both sex classes served as subjects. They were presented with urine obtained from males, from females and a saline control. The females were found to be more active in responding. On the basis of sniffing frequency, they exhibited greater discriminative abilities than did the males. The urine from female donors was sniffed more frequently by all subjects. The frequency of approaching a mark and the time spent in the vicinity of a stimulus are interpreted as being investigatory responses. It seems that the marks deposited by females have a greater salience and that females are more sensitive to olfactory stimuli.

Preferences for salivary odor cues by female hamsters

There is a growing body of data which indicates that saliva may function as a chemosignal in mammals. The salience of this cue in hamsters is investigated. Twelve females were tested in a four-choice olfactorium to determine whether the subjects could differentiate and demonstrate a preference for salivary cues as a function of the dominance status of the stimulus donors and the subjects estrous state. Clear differences in responding were found for estrous as opposed to diestrous females. Estrous females detected and exhibited a preference for male stimuli on the basis of entry and approach measures. Subjects were also found to exhibit sniffing preferences for male odors and possible an avoidance of female odors relative to the saline control. Estrous females appeared to be unable to distinguish between dominant and subordinate males.

Sex differences during initial social contact in the degu (Octodon degus ).

The degu is a hystricomorph rodent endemic to South America. Initial social interactions between like-sexed pairs in a neutral area were found to be heavily influenced by sex-class membership. Twelve of fifteen behavioral categories were differentiated on the basis of sex-class. Descriptive factor loadings indicated that social contact was facilitated in females via olfactory investigation. In males, social avoidance or spacing behaviors were characteristic. In both sexes, scent marking and olfactory investigation was prevalent. These data serve to expand our knowledge of the behavior of this social rodent, and to document the sexual dimorphism evident in early social activities.Robert B. Fischer, Sandra L. Smith, Pamela J. White, and Gary F. Meunier, 1986. Sex differences durina initial social contact in the degu (Octodon degus). --Behav.Processes 12: 67-76. The degu is a hystricomorph rodent endemic to South America. Initial social interactions between like-sexed pairs in a neutral area were found to be heavily influenced by sex-class membership. Twelve of fifteen behavicral categories were differentiated on the basis of sex-class. Descriptive factor loadings indicated that social contact was facilitated in females via olfactory investigation. In males, social avoidance or spacing behdviors were characteristic. In both sexes, scent marking and olfactory investigation was prevalent. These data serve to expand our knowledge of the behavior of this social rodent, and to document the sexual dimorphism evident in early social activities. INTRODUCTION The hystricomorphs appear to exhibit a nigh degree of variability in their social behaviors (Rood, 1972; Kleiman, 1974; Lather, 1981). Some species (e.g., Kerodon) appear to be extremely social whereas others (e.g., Galela) -appear to be much more intolerant of social contact. Substantial sex differences in social behaviors have been documented between and, in some cases, within species (Rood, 1972; Fulk, 1976; Lather, 1981). The degu (Figure 1. An adult degu) is a moderately sized (200 to 300 g) hystricomorph rodent endemic to central Chile and southern Peru (Cendrero cited in Woods & Boraker, 1975; Walker, 1968). The species lives in colonies, forms extended family groups (Wilson & Kleiman, 1974), exhibits little sexual dimorphism, and may on occasion share its rather extensive burrow system with nonconspecifics (e.g., Abrocoma the Chinchilla rats; Walker, 1968; Fulk, 1976). Degus are primarily terrestrial and employ scent mounds and chemosignallicg extensively in their social communication (Fulk, 1976). They have a rather long gestation period (90 days), no regular estrous cycle and give birth to precocial offspring (Weir, 1970). There are indications that captive degu males may be more likely to respond to social interactions with agonism (Kleiman, 1975), whereas females may be more 0376-6357/86/

Discrimination of Male Social Status by Female Hamsters

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The lack of recognition of lactating females by infant Octodon degus

This study was conducted to determine whether urinary ol-factants were capable of communicating information about a males dominance status to females. Voided urine was collected from pairs of dominant and subordinate males. These odors were simultaneously presented to females in a Y-maze olfactometer. Females in estrus spent more time in proximity to the area infused with the odors associated with dominant males. Females, when tested while in diestrus, apparently preferred the odors of submissive males. It is hypothesized that male urinary odors influence male attractiveness and might provide the female with a basis for mate selection.

On the magnitude of reinforcement and fixed-ratio behavior

A series of tests were conducted to determine whether infant degus (Octodon degus) will (a) show sensitivity to maternal olfactory cues and/or (b) discriminate between a novel adult lactating female and their mother. The pups showed no preferences when exposed to an array of different olfactory stimuli but did spend significantly more time in proximity with the novel lactating female than with their mothers. It is hypothesized that the communal rearing systems which are apparently characteristic of degus in the wild, coupled with the novelty of the lactating female, may account for these results.

Effects of enclosure size on activity and sleep of a hystricomorph rodent (Octodon degus)

A large number of studies support the notion that durations of the preratio pause found with fixed-ratio schedules of reinforcement are related inversely to the attractiveness of the reinforcer. An exception to this generalization has recently been reported, however, by Lowe, Davey, and Harzem (1974), who found that magnitude of a liquid reinforcer was positively related to pause durations when all magnitudes were presented within each session. The present data indicate that the Lowe et al. finding may be specific to their experimental design: When performance was studied under steady-state conditions, pause durations were inversely related to reinforcer magnitude.