Receptivity of the female rat (Rattus norvegicus) after male devocalization: A ventral perspective.

Male rats (Rattus norvegicus) emit at least two patterns of vocalization during copulation, the mating call and the pre-ejaculatory call. Both calls promote immobility of the female during lordosis, but the pre-ejaculatory calls are more effective. We undertook, through ventral observations of the mating pair, to determine if the female failed to assume or maintain the lordosis posture when mounted by a devocalized male and also to determine if the devocalized male was providing adequate stimulation to induce receptive behavior. Females were more likely to move away from the devocalized males before assuming the full lordosis posture. Furthermore, they were more likely to move away before the males had a chance to engage in intromissive behavior. However, when the females remained immobile along enough for the males to achieve a mount or intromission, there was little difference in the behavior of either animal that resulted from the devocalization of the male. (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)     

Changes in mating vocalizations over the ejaculatory series in rats (Rattus norvegicus).

Rats (Rattus norvegicus) produce ultrasonic calls during mating. We examined changes in the structure and pattern of such vocalizations over the ejaculatory series. In Experiment 1, vocalizations were recorded from 11 pairs of rats through 3 ejaculatory series and analyzed spectrographically. We classified 4 categories of call by spectral frequency and duration. Calls of low frequency, long duration, and high intensity occurred more often shortly before the ejaculation and were associated with mounting without intromission, a behavior that often occurs shortly before ejaculation. The high-frequency calls did not vary in number across the series. In Experiment 2, vocalizations were recorded from males paired with devocalized females. Males produced all vocalization patterns produced by pairs in Experiment 1. Results suggest that most pre-ejaculatory calls are produced by males and may potentially affect female sexual behavior. (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)     

Analysis of ultrasonic vocalizations emitted by residents during aggressive encounters among rats (Rattus norvegicus).

Determined the extent to which aggressive resident rats emit 40–70-kHz vocalizations and the effect of these signals on intruders. In Exp I, 16 deafened and intact intruder male Long-Evans rats were given 2 encounters with 8 resident Ss. Deafened intruders engaged in a higher duration of immobile or freezing postures than intact Ss. Exp II indicated that the augmentation of freezing found among deafened intruders was not due to an inability to detect ultrasounds made by residents since intruders encountering devocalized resident males showed no reliable differences in specific motor patterns from intruders paired with intact residents. Results demonstrate that 40–70-kHz vocalizations were produced almost entirely by intruding Ss since there were no significant changes in occurrence of these calls when resident males were devocalized. (13 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: 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)     

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)     

Analysis of ultrasonic vocalizations emitted by intruders during aggressive encounters among rats (Rattus norvegicus).

Determined the ultrasonic vocalizations produced by intruders during aggressive interactions and investigated the role of these signals in agonistic behavior of rats. In Exp I, 7 experienced resident male Long-Evans rats were paired with both devocalized and intact vocalizing naive intruder males (n?=?14). Devocalization of the intruder males resulted in a drastic decrease in 50-kHz vocalizations and the elimination of all 22-kHz vocalizations. This almost total absence of ultrasonic vocalizations was not accompanied by any change in resident aggressive behavior or intruder defensive and submissive behavior. In Exp II, 16 naive intruders were tested with either deafened or intact resident males (n?=?8). Similarly, preventing residents from hearing intruder ultrasounds had no detectable effect on any aggressive behavior. These experiments are not consistent with the correlative evidence that intruder-produced 22-kHz vocalizations inhibit the aggressive behavior of the resident. Results show that most of the ultrasonic vocalizations emitted during aggressive encounters were probably produced by the intruder. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in the incidence and sonographic characteristics of antipredator ultrasonic cries in the laboratory rat (Rattus norvegicus).

Long-Evans rats (10 males and 10 females) in a burrow system responded to a cat in the open area by retreating to a burrow and emitting ultrasounds of 18–27 kHz. Females made more frequent ultrasonic cries, with longer durations of ultrasounds. In a 2nd study (19 males and 19 females), sonographic analyses confirmed the more frequent vocalizations of females and indicated that the sound pulses of females were reliably shorter in duration and of higher base frequency than those of males. Also, females emitted more pulses per pulse train with shorter within-train interpulse intervals. Six basic pulse forms were determined, and males emitted more (70%) pulses with negatively accelerated descending frequencies than females (25%). The findings indicate that female rats show qualitatively different antipredator vocalizations than do males and add to previous findings of higher levels of female antipredator defensiveness. (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)     

Effects of ultrasonic vocalizations and male's urine on female rat readiness to mate.

Solitary estrous female Long-Evans rats were presented with ultrasonic vocalizations and/or urine of males to determine their effects on the females' subsequent copulatory behavior. Following exposure to ultrasounds, females exhibited a shorter latency to dart and a higher rate of darting when a male was presented. The vocalization effect was enhanced when male urine was present, but urine alone had no effect. The rate of copulation was also increased by the vocalization priming of the female. For a few individual females, ultrasounds elicited darting in the absence of a male. Results indicate that auditory cues, particularly in association with appropriate olfactory cues, prime estrous females for proceptive behavior. This increases both the likelihood and the rate of sexual performance and, therefore, the probability of successful mating. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of novelty on the reproductive behavior of male Japanese quail (Coturnix coturnix japonica).

In Exp I, 8 sexually deprived male Japanese quail were exposed to 1 of 7 female Japanese quail until they satisfied a 20-min sexual satiation criterion. The female was then replaced with a novel female or was allowed to remain in the test cage undisturbed. Introduction of the novel female did not reinvigorate sexual behavior above levels observed when the female was allowed to remain undisturbed. In Exp II, with 9 males and 15 females, males that were not sexually deprived were tested in the presence of 2 females. During experimental tests, 1 of the females was novel and the other was familiar. During control tests, both of the females were familiar. The presence of a novel female increased overall levels of male sexual behavior and also increased the number of males engaged in reproductive behavior. However, the enhanced sexual behavior was not differentially directed toward the novel or familiar female. Implications of these findings for the mating system of Japanese quail and for studies of the role of novelty in sexual behavior are discussed. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual variation in male vocal traits and female mating preferences in Bufo americanus

We investigated the amount of variation in mating behaviour between and within individual male and female American toads, because both sources of trait variation can influence the course of sexual selection. Males varied in all four call parameters investigated (dominant call frequency, pulse rate, call rate and call duration). Individual males lowered the dominant frequency of their call when they interacted vocally with nearby males. Dominant call frequency was more highly correlated with body size in vocally interacting males than in non-interacting males. Pulse rate of calls primarily varied with water temperature. Call rate and call duration showed the most variation of the four call properties, but this variation was unrelated to male morphology or social interactions. Females varied in three aspects of mating behaviour: two measures of pair formation and their preference for dominant frequency of male calls. The body size of paired males varied between females both in pairings initiated by either sex and in pairings initiated only by females. Males chosen by females were usually larger than average, although age and prior breeding experience of females did not affect mate choice. Playback experiments indicated that female preference for calls of low dominant frequency depended on the temporal patterning of alternative calls presented. Each of the four male vocal properties showed significant repeatability, but only one of the three aspects of female mating behaviour was repeatable. We discuss how different degrees of repeatability in sexual traits of males and females may influence the action and detection of sexual selection in this and other species. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.     

Certainty of paternity and paternal investment in eastern bluebirds and tree swallows

Extra-pair paternity is common in many socially monogamous passerine birds with biparental care. Thus, males often invest in offspring to which they are not related. Models of optimal parental investment predict that, under certain assumptions, males should lower their investment in response to reduced certainty of paternity. We attempted to reduce certainty of paternity experimentally in two species, the eastern bluebird, Sialia sialis, and the tree swallow, Tachycineta bicolor, by temporarily removing fertile females on two mornings during egg laying. In both species, experimental males usually attempted to copulate with the female immediately after her reappearance, suggesting that they experienced the absence of their mate as a threat to their paternity. Experimental males copulated at a significantly higher rate than control males. However, contrary to the prediction of the model, experimental males did not invest less than control males in their offspring. There was no difference between experimental and control nests in the proportion of male feeds, male and female feeding rates, nestling growth and nestling condition and size at age 14 days. We argue that females might have restored the males' confidence in paternity after the experiment by soliciting or accepting copulations. Alternatively, males may not reduce their effort, because the fitness costs to their own offspring may outweigh the benefits for the males, at least in populations where females cannot fully compensate for reduced male investment. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.     

Epitopes fused to F-pilin are incorporated into functional recombinant pili

Blue crabs mate immediately after the female's final moult. We tested the influence of female moult stage, sex ratio and male size on the pre-mating behaviour of both sexes, and the ability of males to pair with females and aggressively compete for access to females. We observed crabs in field enclosures and surveyed pre-copulatory mate-guarding patterns in the field. Female behaviour changed as they progressed through the final moult cycle, such that early moult-stage females avoided males, but late moult-stage females initiated pair formation. The changes in female behaviour influenced both the behaviour and pairing capability of males. Males courted and paired with late moult-stage females on their first attempt, but pursued early moult-stage females because their first attempts to pair often failed. In the field, early moult-stage females were paired less often than late moult-stage females. The pre-mating behaviour of both sexes also varied with sex ratio; when males were abundant, males traded courtship for forced capture and females courted less. Large males were more successful at take-overs, but did not pair more often with late moult-stage females, suggesting that large males do not consistently guard for less time than small males. The changes in female behaviour are consistent with the female's need to avoid the costs of guarding and suggest that females influence how pre-copulatory mate guarding occurs in this species.Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.     

P-selectin and MAC-1 mediate monocyte rolling and adhesion to ECM-bound platelets under flow conditions

Ultrasonic vocalizations were tape recorded from five pairs of copulating mice and subjected to spectrographic analysis. As expected, the mice emitted numerous 70-kHz vocalizations. At the beginning of the test, before copulation began, 70-kHz calls were emitted almost continuously, while calls with lower spectrographic frequencies were not observed. Subsequently, bursts of 70-kHz calling generally began shortly before mounts and intromissions and persisted until dismount. Intermixed with these 70-kHz calls were additional vocalizations of about 40 kHz. Calling rates were highest just prior to intromission. Once intromissions began, 70-kHz calls continued at a lower rate until dismount; however, 40-kHz calls occurred infrequently. In a second experiment, the male was found to emit the majority of the 70-kHz calls and all of the 40-kHz calls. When the male was devocalized, few calls were detected, regardless of whether the female was able to call. If the male was not devocalized, high rates of calling were detected, even if the female was devocalized.     

Dominance in intermale encounters and subsequent sexual success in mice.

In Exp I, when previously isolated male CD-1 mice (n?=?26) were paired and given a female, they fought before beginning to mount, and the more aggressive male ejaculated somewhat more frequently. Males housed together (n?=?26) for several days showed little aggression when jointly given a female, but those that were more aggressive in the home cage clearly ejaculated more frequently. In Exp II, with 144 Ss, males were paired for 4 days after a period of isolation. More aggressive males showed more ejaculations when subsequently tested individually with females, but not when pair members conjointly encountered females. In Exp III, 60 males were paired for several weeks before encountering females. In cases in which home cage dominance was constant, the more aggressive males ejaculated more frequently both when tested individually and when tested as pairs. Findings indicate that success in reproductive behavior in mice is contingent on dominance in intermale aggressive encounters. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual dimorphism in ultrasonic vocalizations of mice (Mus musculus): Gonadal hormone regulation.

Male mice, during courtship and sexual behavior, vocalize substantially more 70-kHz ultrasounds than do females. Four experiments conducted with 109 male and female DBA/2J and ADK2F? mice demonstrated that testosterone propionate (TP) substantially increased ultrasonic emissions and mounting by ovariectomized females and that long-term gonadectomized males and females increased their amount of ultrasound production in response to TP to approximately the same levels. From these results it is suggested that the sexual dimorphism normally seen in ultrasonic vocalizations can be accounted for by the activational effects of androgen in adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The function of Barbary macaque copulation calls

In a wide variety of animal species, females produce vocalizations specific to mating contexts. It has been proposed that these copulation calls function to incite males to compete for access to the calling female. Two separate advantages of inciting male-male competition in this way have been put forward. The first suggests that as a result of calling, females are only mated by the highest ranking male in the vicinity (indirect mate choice hypothesis). The second proposes that copulation calling results in a female being mated by many males, thus promoting competition at the level of sperm (sperm competition hypothesis). In this paper, I give results from the first experimental study to test these hypotheses. Playback was used to examine the function of copulation calls of female Barbary macaques (Macaca sylvanus) in Gibraltar. Although rank did not affect lone males' likelihood of approaching copulation calls, when playbacks were given to pairs of males only the higher ranking individual approached. Moreover, females were mated significantly sooner after playback of their copulation call than after playback of a control stimulus. These results suggest that the copulation calls of female Barbary macaques play a key role in affecting patterns of male reproductive behaviour, not only providing an indirect mechanism of female choice, but also promoting sperm competition by reducing the interval between copulations. Potential fitness benefits of inciting male-male competition at these two levels are discussed.