Communication among hamsters by high-frequency acoustic signals: II. Determinants of calling by females and males.

A previous study by the authors (see record 1978-09410-001) showed that basal rates of high-frequency vocalization by estrous female hamsters exceeded those typical of nonestrous females. In the present 6 studies with random-bred (Lak:LVG) hamsters, even higher rates of calling by estrous females were provoked by male odors (male shavings or anesthetized males). This suggested that cues which normally indicate a male's proximity can increase the rate of high-frequency calls by an estrous female. These findings are consistent with a view of female "ultrasounds" as sexual advertisements which indicate the locations, sexual receptivity, and relative passivity of estrous females to nearby male conspecifies. Male hamsters also produced ultrasounds at rates that seemed to depend on the availability of potential males. Brief exposure to an awake female stimulated male calling; however, estrous females provoked higher call rates than did nonestrous females. Exposure to anesthetized females also increased the rate of male calling, which suggests that the stimulation of male calling by awake females depends in part on female odors. These results suggest that both male and female ultrasounds are parts of a communication system that facilitates reproduction by helping to coordinate social behavior with endocrine state. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male-produced ultrasonic vocalizations and mating patterns in female rats.

Investigated the influence of male-produced 50-kHz vocalizations on mating behavior and choice of partner in estrous female rats. In Exp I, 17 estrous female Long-Evans rats were given a mating-choice test; 2 tethered males, one of which was devocalized, were used as incentives. Darting was directed toward the vocalizing male more frequently than toward the muted test partner, but ultrasonic vocalizations had no influence on visit rate or the amount of time that the females spent with each male. When 2 intact or 2 muted males were used as stimulus objects, the females' solicitation behavior was more evenly distributed between the 2 males. In Exp II, 16 estrous females were given a mating-choice test between 2 muted males; tape-recorded 50-kHz vocalizations or tape hiss was transmitted from a speaker located behind one of the males. Females spent equal amounts of time with the tethered males in both the vocalization and tape-hiss conditions; however, females directed more darting toward the males that were tethered in front of the speaker transmitting the ultrasonic vocalizations than toward the other muted tethered males. Findings demonstrate that the principal function of the male-produced ultrasounds is to facilitate and orient the solicitation behavior of the estrous female during mating. The vocalizations have little demonstrable effect in attracting the female to the immediate physical proximity of the male. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of gonadal hormones and sexual behavior on ultrasonic vocalization in rats: II. Treatment of males.

Male Long-Evans rats were tested with estrous female rats in a divided cage to determine whether ultrasonic vocalizing varies as a function of recent sexual behavior or hormonal condition. In Exp I, when males were tested after 3 intromissions, a short latency to vocalization and a high rate of 50-kHz pulses occurred. 40% of the males changed their vocalization to 22-kHz pulses. With sexually fatigued males, long vocalization latencies and low vocalization rates were observed, and no males shifted to 22 kHz. Rates were intermediate with control males. In Exp II, a decline in vocalization rate occurred following castration of male rats compared with sham-operated controls. In both experiments the male nosed the screen divider during high-rate ultrasound production, maximizing contact with the female. Darting by females appeared only when ultrasonic pulse rates were high. The abrupt shift from 50- to 22-kHz vocalizing was characteristic of males with short intromission latencies. Data suggest that gradation of vocalization is correlated with the sexual readiness of the male and that vocalization may facilitate female darting behavior. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of gonadal hormones and sexual behavior on ultrasonic vocalization in rats: I. Treatment of females.

Ultrasonic vocalizations were measured when male Long-Evans rats were placed with ovariectomized females that had experienced various hormonal and behavioral treatment. In Exp I, 18 males were tested with females in each of the following conditions: nonestrous (OVX), estrogen treated (E), estrogen and progesterone treated (EP), and estrogen and progesterone treated and given 2 intromissions from a stud male prior to testing (EPI). Control conditions included clean cage (CL) and cage soiled by an estrous female (SOI). The treatments differed in effect on rate and maintenance of vocalization, in the order of greatest to least: EP, E, EPI, and OVX (equal), SOI, and CL. In tests in which males produced a high rate of vocalization, some males with short intromission latencies shifted from the normal 50-kHz pulse to a 22-kHz pulse. In Exp II, the effect of the female's vocalization and movement on the rate of and latency to vocalization was measured. 21 males were presented with each of the following stimulus conditions: estrous female with red light (EP), estrous female without red light (EP dark), estrous anesthetized female (EP anes), and nonestrous anesthetized female (OVX anes). Effects on vocalization of various treatments were in descending order: EP and EP-dark (equal), EP anes, and OVX anes. Data suggest that the 50-kHz vocalizations constitute a graded response influenced by the female's hormonal and sexual condition. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of the ultrasonic vocalization of the female rat (Rattus norvegicus) in sexual behavior.

Both male and females rats vocalize ultrasonically during mating. In this article, experiments were done to examine the effects of the female's mating call on rat mating behavior. In the first experiment, females copulated with intact males before and after surgical devocalization. In the second experiment, intact females copulated twice with a male: once when they were able to hear and once when they were temporarily deafened with a medical ear mold. In the third experiment, tape recorded ultrasounds were placed in the presence of devocalized females while they were copulating with intact males. In the control condition, tape hiss was presented. In each experiment, it was observed that the female darted more if communications were disrupted (i.e., female devocalized or male deafened). Playback partially reduced darting to control levels. No other behavior was affected consistently across all experiments. Female calls might facilitate self-regulation of mating behavior, or they might focus the male's attention on her proceptive behaviors. It is also possible that the female calls could alter the stimulus properties of the male's behavior, indirectly affecting her own behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasonic vocalizing by adult female mice (Mus musculus).

Conducted 5 experiments, using 1,029 female and 805 male mice, to examine adult female mouse ultrasound emission. Results indicate female ultrasonic vocalizing to be (a) typically displayed among female mouse dyads and (b) comparable to the ultrasonic vocalizing levels obtained among male–female pairs. Genotypically based variations in the production of ultrasounds by females were also noted. Like males, socially naive females readily ultrasonically vocalized to anesthetized female conspecifics and rarely vocalized to anesthetized males. Unlike males, socially experienced females emitted few ultrasounds to either female urine or female-soiled cage shavings. Although social experience increased the ultrasound emission of males to female sex cues, the production of ultrasounds by females to these cues was decreased by social experience. Implications with regard to the existence of a behavioral/functional sexual dimorphism in adult mouse ultrasonic vocalizing are discussed. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of devocalization of the male on mating behavior in rats.

Three experiments investigated the effects of devocalization of male rats on the copulatory behavior of 33 male and 9 female Long-Evans rats. No differences in any measure of masculine copulatory performance were found between vocalizing and muted males; however, estrous females mated with vocalizing males exhibited more frequent darting behavior than females mated with muted males. Females paired with vocalizing males in a tether apparatus exhibited more patterns of proceptive behavior per unit of time than did females paired with devocalized males, although the temporal distribution of this behavior, with respect to mounts by males, was unchanged. Conversely, patterns of receptive behavior were unaffected by devocalization of the male. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Communication among hamsters by high-frequency acoustic signals: III. Response evoked by natural and synthetic ultrasounds.

Male and female golden hamsters showed clear behavioral responses to playback of recorded ultrasounds. In particular, it was found that (a) estrous females increased their rates of ultrasound production upon exposure to recorded ultrasounds (Exp I); (b) hamsters of both sexes, exposed to natural or artificial high-frequency calls in a Y-maze, were able to localize the ultrasound source and were attracted to it (Exp II); and (c) estrous females performing lordosis after brief male–female contact maintained that posture significantly longer in the presence of recorded ultrasounds than in silence (Exp III). On the basis of these findings and the results of other studies of hamster social behaviors, the functional significance of hamster ultrasounds is discussed in relation to other elements of a hormone-dependent communication chain regulating hamster reproduction. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensory requirements for noncontact penile erection in the rat.

Physical contact is not necessary for male rats to display penile erection when placed in the vicinity of females in estrus (noncontact erection, NCE). The modality and reception of sensory stimuli for the induction of NCE were analyzed. Olfactory bulbectomy eliminated NCE, and destruction of olfactory mucosa by zinc sulfate solution caused a significant suppression of NCE, whereas removal of the vomeronasal organ had no effect. Fresh urine collected from estrous females, but not fresh feces, induced NCE. Neither devocalization of estrous females by cutting the inferior laryngeal nerve nor deprivation of visual cues by placing an opaque barrier between the subjects and stimulus females disrupted NCE. The results indicate that olfactory cues emitted by estrous females induce NCE via the olfactory epithelium. Contrary to what had been suggested by previous experiments, vomeronasal inputs are not indispensable for the induction of NCE. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of pheromones in the regulation of estrous cycle duration in the guinea pig

A decrease in estrous cycle duration, due to shortening of the period of vaginal closure (VC), has been observed in female guinea pigs exposed to the odor of urine from males of the same species. VC shortening was also observed in females exposed to the odor of female urine collected during the period of vaginal opening (VO). No alteration in VC duration occurred, however, in females exposed to urine collected in the 1st 7 days of VC. Also VC shortening did not occur in bulbectomized females exposed to the odor of male urine. Therefore, it was concluded that guinea pig urine, when highly concentrated, contains pheromones capable of shortening estrous cycle VC.     

The role of vaginal secretion in hamster sexual behavior: Males' responses to normal and vaginectomized females and their odors.

Two experiments (with 60 adult male hamsters and 4 sexually naive male hamsters) examined the importance of vaginal secretion relative to other feminine odors for attraction of males and elicitation of copulatory behavior by comparing the behavior of males toward normal females with that toward vaginectomized Ss. Males were more attracted to intact females than to vaginectomized Ss when odors were the only cues available and also when auditory, visual, and odor cues were available but contact was prevented. There were no differences in the attractiveness of estrous and diestrous Ss whether intact or vaginectomized. When males and females were allowed to interact, there were no differences in any measures of male sexual behavior toward normal vs vaginectomized females, which indicates that the presence of vaginal secretion is not necessary for male sexual behavior. The significance for conceptions of pheromone action in mammals is discussed. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of male pre-ejaculatory vocalizations on female receptive behavior in the rat (Rattus norvegicus).

Both male and female rats (Rattus norvegicus) emit ultrasounds during copulation. Bursts of ultrasounds from males that occur as ejaculation approaches are lower in frequency, longer in duration, and louder than those that appear earlier in the ejaculatory series. We attempted to determine if these pre-ejaculatory calls affect female sexual behavior. The behavior of females paired with devocalized males was compared with that of females paired with intact males, and in a second experiment tape-recorded vocalizations were played to females paired with devocalized males. Females were less receptive when paired with devocalized males; they were less likely to remain stationary when males attempted to mount. Playback of both types of calls restored female immobility toward control levels, although pre-ejaculatory calls were more effective than mating ones. Pre-ejaculatory calls restored running and trailing levels somewhat toward control level but to a lesser extent than female immobility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Female-enhanced aggression in male rats: Effects of genital anesthesia, castration, or preoptic lesions.

Male rats that had cohabited with ovariectomized females for 2 weeks became more aggressive toward male intruders after a novel estrous female had been placed in their home cages for a period of 4 hr on the previous day. No increase in aggression was seen in males exposed to anestrous females. Genital anesthesia did not attenuate the female-enhanced aggression effect. By contrast, no enhancement of aggression was observed in long-term castrated males after 24 hr of exposure to estrous females. Rats with bilateral electrolytic lesions in the medial preoptic area showed a normal female-enhanced aggression effect. The observations that exposure to females facilitates aggression in males subjected to genital anesthesia and in males with preoptic lesions raise the possibility that copulatory cues are not always required for the effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraspecific sexual preferences of female hamsters.

Studied the sexual preference behavior of 32 estrous females of 3 species of hamsters of the genus Mesocricetus by introducing individual females into an arena with a pair of males from 2 different species. When 1 male of the pair was a conspecific, females of all 3 species spent significantly more time investigating the conspecific male. When neither male was a conspecific, female Turkish hamsters (M. brandti) strongly preferred male Romanian hamsters (M. neutoni) to male Syrian hamsters (M. auratus), and female Romanian hamsters preferred male Turkish hamsters to male Syrian hamsters. Female Turkish hamsters displayed significantly more presentation behavior than did Romanian females, and Syrian females rarely presented. Female Turkish hamsters also displayed a stronger degree of preference behavior to a conspecific male than did females of either of the other species. The relatively stronger sexual preferences and greater amount of presentation displayed by Turkish hamsters may relate to the greater opportunity for sympatry with closely related forms and the polymorphic state of this species in the wild. The similarity of Turkish and Romanian hamsters on several characteristics may explain the preference of these species for each other when the alternative was a Syrian hamster. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Elicitation of male mouse (Mus musculus) ultrasonic vocalizations: I. Urinary cues.

18 experiments on a total of 223 DBA/2J, AKD2F1/J, and hybrid mice, plus additional social-experience mice, examined the physical characteristics and physiological modulation of the ultrasound-eliciting property of female urine. The following results were found: An excitatory factor exists in female urine, and male urine is essentially neutral with regard to ultrasound elicitation. The ultrasound-eliciting factor is relatively nonvolatile and heat resistant, although extreme heat will destroy its activity. Ovarian and adrenal hormones appear relatively unimportant. Exogenous androgen suppresses female urinary ultrasound-eliciting activity. Castration of males did not improve the ability of their adult urine to elicit ultrasounds, nor did administration of androgen to neonatal females suppress the ability of their adult urine to elicit ultrasounds. Hypophysectomy eliminates the ultrasound-eliciting properties of female urine, which suggests that the dimorphism in ultrasound elicitation may be regulated by pituitary hormones. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Communication among hamsters by high-frequency acoustic signals: I. Physical characteristics of hamster calls.

In Exp I, 2 random-bred (Lak:LVG) female hamsters emitted high-frequency sounds at average intensities of 53 db (SPL). These calls tended to be 80–200 msec long and to emphasize frequencies of 34–42 kHz. However, female "ultrasounds" typically included rapid fluctuations in frequency and amplitude. In Exp II, male hamsters also emitted high-frequency vocalizations, with dominant frequencies of 32–38 kHz and average durations of 70–250 msec. Although male cells generally included fewer rapid changes in amplitude and frequency than did female calls, male call structures depended on contextual factors. Calls produced by males in the presence of estrous females tended to have lower minimum frequencies, higher maximum frequencies, longer durations, and fewer rapid frequency changes than calls by solitary males. These results show that both sex differences and situational factors influence the structures of hamster ultrasounds. The frequency and amplitude changes typical of calls by females and solitary males should facilitate the localization of a calling individual over moderate distances. Calls by males in the presence of females should be more difficult to localize and might operate over shorter distances to serve a different social function. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tests of preferences of deer mice (Peromyscus maniculatus bairdi) for individuals and their odors as a function of sex and estrous condition.

18 experiments investigated deer mice's preferences for cues from conspecifics in relation to their presence, sex, and estrous condition. Both males and females consistently preferred bedding soiled by conspecifics to clean bedding. Males given recent testing in a seminatural enclosure preferred bedding soiled for 6–7 hrs by females to that soiled by males. Other sexually experienced males displayed no such preference; however, such males did prefer bedding soiled by females for 6–9 days to that soiled by males. There was no consistent evidence that males preferred the odor of estrous females to those in diestrus. Results suggest that there is great variability among rodent species regarding the effectiveness of cues related to sex and estrus; preferences for estrus are not universal. In nature the important signal for a male deer mouse may be the presence of a female that may soon become estrous. The current estrous state may be of less importance. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasonic signaling in the gerbil (Meriones unguiculatus): Social interaction and olfaction.

Conducted 3 experiments with 53 gerbils to assess the conditions for ultrasonic emission. Exp I indicates that isolated Ss rarely emitted ultrasounds, males emitted at a higher rate than females, and emission rates ordinarily decreased with continual testing. Ultrasonic emissions were stimulated by olfactory cues from conspecifics. Exp II demonstrates that dominant males emitted more ultrasounds than subordinate males and responded to cues from anesthetized, shaved, or dead animals or from anesthetized animals in the dark. Exp III shows that body hair elicited ultrasounds from males unless organic materials were removed from the hair with chloroform. Hair was an effective stimulus at a distance only when an airstream blew the volatiles over the recipient. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Odor preference and urine-marking scales in male and female rats: Effects of gonadectomy and sexual experience on responses to conspecific odors.

Investigation and urine-marking responses of 112 male and female Long-Evans rats toward conspecific urine odors were recorded in pair-wise comparison tests. Each of 16 S groups was given 15 preference tests, 1 for each of the possible pairs of 5 urine odors and a no-odor control (N). The urine sources were own group (G), intact male (M), castrated male (Mc), ovariectomized female (Fo), and estrous females (F). Results were scaled by using a technique based on L. L. Thurstone's (1927) law of comparative judgment. Intact males with sexual experience ordered their odor preferences N?     

Ultrasonic vocalizations by male house mice (Mus musculus) to novel odors: Roles of infant and adult experience.

Conducted 2 experiments to examine 70-kHz ultrasonic courtship vocalizations by adult male mice to novel odors following exposure to these odors in infancy and/or adulthood. Exp I, with 72 males, demonstrated that adult males normally do not vocalize to the urine of female rats but would if adult female mice odorized with female rat urine were repeatedly encountered postpubertally. On the other hand, encountering their own mother odorized with female rat urine from birth until weaning did not promote vocalizations to the urine of female rats. Exp II, with 100 males, examined vocalizations to the urine of female mice whose urinary odor was altered by the ingestion of fenugreek, a spice. Greater amounts of vocalization again were seen by males that as adults encountered females that had ingested fenugreek. Again, experience with the novel odor during infancy was not associated with elevated vocalizations during adulthood either to fenugreek-altered urine or to the fenugreek odor itself. Vocalizations to 2 different novel odors occurred only after an adult male had encountered an adult female odorized with the novel odor. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)