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)     

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)     

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)     

Role of olfactory stimuli during copulation in male and female rats.

Describes 3 experiments with a total of 74 gonadally-normal male and 29 ovariectomized female Long-Evans rats. Male and female reactions toward odors from novel and original partners were observed prior to the male's attaining his 1st or 2nd ejaculation. The male's reaction depended upon the sexual condition of the female. Only prior to their initial ejaculation did the males prefer their original partner's odors to those of novel females and only if the odors were collected from the females prior to copulation. This finding corresponded with observations of the male's random choice of partner during copulation. Females responded nonpreferentially if they had copulated prior to testing and showed a marked decrease in responsiveness as copulation continued. Prior to copulation females preferred the odors from males which had not copulated to those of males which had. (25 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)     

Female regulation and choice in the copulatory behavior of montane voles (Microtus montanus).

To study female choice of mating partners in montane voles, a male was tethered at each end of an elongate chamber, and an estrous female was allowed to move betweeen the 2 males and a neutral area. In Exp I, using 16 females and 32 males, females with a choice of 2 gonadally intact males copulated preferentially with 1 of them. Preferred males were more effective than nonpreferred males at gaining intromission and had more thrusts per intromission. In Exp II, with 10 females, 10 castrated males, and 10 sham-operated males, females spent more time with and mated preferentially with intact rather than castrated males. It is therefore suggested that the opportunity to copulate is reinforcing for female voles and that they display distinct preferences, correlated with copulatory stimulation, for some partners. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

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)     

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)     

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)     

Effects of male social status on reproductive success and on behavior in mice (Mus musculus).

Differences in reproduction as well as in behavior in the presence of females were evaluated according to dominant and subordinate male rank in albino mice, in the temporary absence of each male's antagonist. Dominant males reproduced more successfully than subordinate males. Subordinate males were generally inactive, except for displacement activities, during the first 15 min they were exposed to female partners. These findings suggest that mechanisms other than male–male interference or mating order may be operating or influencing behavior and reproductive results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social olfaction in male brown lemmings (Lemmus sibiricus?=?trimucronatus) and collared lemmings (Dicrostonyx groenlandicus): II. Discrimination of mated and unmated females.

Four experiments were conducted with 32 brown and 80 collared male lemmings. When tested in a Y-maze olfactometer, both species preferred the odor of unmated receptive females to the odor of females with which they had just copulated. Similarly, sexually satiated Ss preferred the odor of an unmated receptive female to that of a strange female that had recently copulated with another male. Sexually experienced Ss without recent copulatory experience also demonstrated this preference, but sexually naive Ss did not. Sexually satiated collared lemmings preferred the odor of bedding from a novel estrous female to bedding from the female with which they had just copulated even when the bedding was collected before mating occurred. Results suggest that discrimination between prior mates and unmated females may be based on individual recognition as well as recognition of subclasses of females (i.e., mated vs unmated, familiar vs unfamiliar). (22 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.     

Copulatory behavior of deer mice (Peromyscus maniculatus): II. A study of some factors regulating the fine structure of behavior.

In 7 experiments on factors regulating copulatory behavior in deer mice, changes in copulatory behavior across series within a test reflected changes in both male and female, with the male apparently predominant. Even when mating with females of a species with a very different copulatory pattern (cactus mice), male deer mice retained the species-typical pattern. Mating in a 2-male/1-female condition produced little alteration in copulatory behavior from that in the 1-male/1-female condition. Under some test conditions, levels of aggressive behavior in the 2-male/1-female condition was considerable. There was generally covariation among body weight, social dominance, and copulation, with heavier males being dominant and ejaculating more often than lighter males. When females were in hormone-induced estrus, mount and intromission latencies were longer and ejaculation frequencies were lower than with either cycling or postpartum estrus. Significant differences between cycling and postpartum estrus were detectable with a within-Ss design. Mate familiarity had little effect on parameters of copulatory behavior once initiated. Effects of both male and female were detected when mating partners were changed between tests and test–retest correlation coefficients were calculated. (67 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interference risk and the function of dynamic shifts in calling in the gray treefrog (Hyla versicolor).

Male gray treefrogs call to attract females under challenging acoustic conditions. At higher chorus densities, there is considerable background noise and a good chance that a male's calls will often be overlapped by calls of other individuals. Call overlap may reduce the probability of mating because females prefer calls with internal pulse structure that is not obscured. With increases in acoustic stimulation, males lengthen call duration while simultaneously reducing call rate such that "pulse effort" changes little. In our study, we tested the "interference risk hypothesis." This proposes that males change call duration so that, on average, there will be a sufficient number of pulses and interpulse intervals clear of acoustic interference per call to attract a female. However, female choice experiments employing call alternatives of different durations, rates, intensity levels, and degrees of call overlap refuted this hypothesis. Our results leave open the possibilities that the dynamic shift in the two components of pulse effort are related to the problem of call detection in a noisy environment or are responses by males to the perceived threat of competition for females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of voles (Microtus montanus and M. ochrogaster) in multiple-female test situations.

12 male prairie voles and 12 male mountain voles were given test of copulatory behavior with 1, 2, or 4 mating partners. Changes in the number of available partners produced minimal changes in the parameters of copulatory behavior in males of the 2 species. Male montane voles generally copulated with more of the females, showed a lesser tendency to concentrate copulations on a single female, and changed females more often than did prairie voles. These differences are consistent with differences in social structure reported in field studies and may reflect processes underlying species differences in social organization. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Females prefer leading males: relative call timing and sexual selection in katydid choruses

Females of several acoustic insects and anurans have recently been shown to orient preferentially to the leading of two identical male calls presented in close succession. We studied this phenomenon via two-choice phonotaxis trials in the neotropical katydid Neoconocephalus spiza and found that females avoided male calls occurring during an interval beginning immediately after the onset of a leading call. This avoidance occurred whether or not the following call was overlapped by the leader, indicating that the mechanism of preference for leading calls may represent a psychoacoustic precedence effect rather than simple call masking. We also found that females preferred leading calls as long as the amplitude of the following call was not more than 2 dB higher than the leader. Under certain circumstances, preferences for leading calls remained when females were presented with a sequence of four calls. Thus, preferences for leading calls probably influence a male's attractiveness and mating success in complex natural choruses: females are expected to orient towards males producing leading calls regardless of call length (and the probability of overlapping a following call), when the leading call is up to 1.5 times as distant as a follower, and when succeeded by multiple followers. We suggest that female preferences for leading male calls represent sensory biases that originated in contexts unrelated to sexual selection. None the less they currently play an important role in sexual selection and influence individual male signalling behaviour, and thus chorus structure. Copyright 1998 The Association for the Study of Animal Behaviour.     

Relative Contributions of the Male and the Female to Sexual Behavior and Reproductive Success in the Japanese Quail (Coturnix japonica).

Two contrasting investigative techniques provided evidence consistent with the interpretation that female quail (Coturnix japonica) regulate male copulatory behavior by the duration of their immobility and through this behavioral mechanism they also control the rate of fertilization of their eggs. In Experiment 1, copulation tests with males and females from different genetic lines showed that the type of female that participated in a copulatory test significantly influenced the latency of the male's grab, mount, and cloacal contact responses and also determined the efficiency of the male's copulatory behavior. These measures of male performance were correlated with female immobility in Experiment 2, which used a more homogeneous population of quail. Furthermore, 2 of these measures (copulatory efficiency and the latency to make cloacal contact) were correlated with fertilization rate. (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)