Conditioning of appetitive and consummatory sexual behavior in male Japanese quail.

Two different types of stimulus objects, a live female quail artificially adorned with bright orange feathers and an inanimate toy dog, served as conditioned stimuli. For subjects in experimental groups, the conditioned stimuli were presented shortly before access to a sexually receptive normal female quail. For subjects in control groups, exposure to the conditioned stimuli was unpaired with copulatory opportunity. Subjects in the experimental but not in the control groups quickly came to approach the location of the conditioned stimulus objects. When an adorned female quail served as the conditioned stimulus, the conditioned approach behavior was controlled by a combination of the presence of the orange adornments and the visual cues of the head and neck of the female bird, and the approach behavior persisted as the adorned female moved to new locations. When the toy dog served as the conditioned stimulus, the conditioned approach behavior was limited to the spatial cues that surrounded the toy dog during conditioning trials. Although both types of stimulus objects evoked conditioned approach behavior, only the adorned female stimulus supported copulatory behavior. This last finding indicates that copulatory behavior can become redirected toward novel stimuli as a result of conditioning, but only under special circumstances. The results are consistent with the suggestion that appetitive components of reproductive behavior are more susceptible to conditioning than consummatory components. Possible reasons for this are discussed, together with implications of the results for the contribution of conditioning processes to sexual selection.     

Effects of enclosure size on sexual behavior of Japanese quail (Coturnix japonica)

The authors determined whether results of experiments on copulatory and affiliative behavior of pairs of Japanese quail (Coturnix japonica) conducted in a closely confining apparatus would predict behavior in a large enclosure in which female quail could avoid contact with male quail. As found previously in studies of closely confined quail, in a large enclosure containing numerous barriers, both unmated female quail and mated female quail laying unfertilized eggs were more likely to remain near a confined male quail than were mated female quail laying fertilized eggs. Furthermore, the number of copulations that a pair engaged in when closely confined predicted the number of copulations that they engaged in when they were in the large enclosure. Patterns of affiliation and of mating in a confining laboratory apparatus thus predicted behavior in a larger enclosure that provided female quail with opportunity to avoid contact with male quail.     

Extinction of conditioned sexual responses in male Japanese quail (Coturnix japonica): role of species-typical cues

The authors examined how a conditioned stimulus (CS) that included species-typical cues affected the acquisition and extinction of conditioned sexual responses in male quail (Coturnix japonica). Some subjects were conditioned with a CS that supported sexual responses and included a taxidermic head of a female quail. Others were conditioned with a similar CS that lacked species-typical cues. Pairing the CSs with access to live females increased CS-directed behavior, with the head CS eliciting significantly more responding than the no-head CS. Responding to the head CS persisted during the 42-day, 126-trial extinction phase; responses to the no-head CS extinguished. Responding declined when the cues were removed or the subjects were sexually satiated. Possible functions and mechanisms of these effects are discussed.     

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.     

Hormonal control of sexual attraction in pseudohermaphroditic female dogs

Groups of female dogs exposed to different degrees of androgenic stimulation during development and a control group of ovariectomized females were tested for their attraction to tethered male and female stimulus animals. Attraction to the male was measured before and after administration of estradiol, and attraction to an estrous female was tested before and after administration of testosterone propionate (TP). Time spent visiting the tethered male was approximately equal for all groups prior to hormone treatment, but after receiving estradiol, control females exhibited a pronounced increase in visiting time; the second longest visits were paid by females that had received moderate amounts of androgen before birth; more heavily androgenized females exhibited no increase in attraction to the male despite estradiol injections. Visits to the estrous female before administration of TP were longer for some groups than for others, but there was no relation between the degree of perinatal androgenization and mean visiting time. After injections to TP the most pronounced increase in visiting was shown by females that had received the largest amounts of androgen during development, and the second largest increase occurred in the prenatally androgenized group. Control females showed the smallest increase in visiting time.     

Imitative learning in Japanese quail (Coturnix japonica) depends on the motivational state of the observer quail at the time of observation

The 2-action method was used to examine whether imitative learning in Japanese quail (Coturnix japonica) depends on the motivational state of the observer quail at the time of observation of the demonstrated behavior. Two groups of observers were fed before observation (satiated groups), whereas 2 other groups of observers were deprived of food before observation (hungry groups). Quail were tested either immediately following observation or after a 30-min delay. Results indicated that quail in the hungry groups imitated, whereas those in the satiated groups did not, regardless of whether their test was immediate or delayed. The results suggest that observer quail may not learn (through observation) behavior that leads to a reinforcer for which they are unmotivated at the time of test. In addition, the results show that quail are able to delay the performance of a response acquired through observation (i.e., they show deferred imitation).     

Imitation in Japanese quail: The role of reinforcement of demonstrator responding

Imitative learning has been difficult to demonstrate in animals, partly because techniques have not adequately ruled out alternative accounts based on motivational and perceptual mechanisms (Zentall, 1996). Recently, it has been proposed that differences in the effects of observation of two very different responsetopographies would rule out such artifactual, alternative accounts (Akins & Zentall, 1996). In the present research, we confirmed that strong evidence for imitation can be found in Japanese quail, and that such imitation requires the imitator’s observation ofreinforced responding by the demonstrator. Thus, under the present conditions, it appears that an observer will imitate a demonstrated responseonly if it also observes the appetitive consequences of that response.     

Sexual-discrimination learning in male Japanese quail (Coturnix coturnix japonica)

We investigated how male Japanese quail (Coturnix coturnix japonica) learn through extensive social and sexual experience to discriminate between male and female conspecifics. Opportunity for heterosexual copulation was important for this learning, but even extensive copulatory opportunity was not sufficient to produce a sexual discrimination; subjects also required exposure to other males. Exposure to females after copulatory opportunity did not produce a sexual discrimination but facilitated its acquisition. Time or exposure to only the visual features of male birds (provided by taxidermic models) after copulatory opportunity did not result in differential responding to male and female conspecifics. Finally, presenting stimulus birds one at a time proved to be a more sensitive test of sexual-discrimination learning than presenting two stimulus birds at the same time. The results indicate that sexual-discrimination learning is similar to conventional associative learning.     

Another psychobiological view of sexual differentiation

The major psychobiological theory of sex differences is based on the hypothesis that hormones induce sex differences in neural organization. Hormonally masculinized or feminized brains are thought to underlie subsequent behavioral sex differences. This theory and the constructs, arguments, and evidence used in its support are closely examined. Some conceptual problems with widely used arguments are identified and discussed. Behavioral, physiological, and anatomical evidence from studies of animal sexual behavior is reviewed. It is concluded that the evidence fails to support generally accepted views that early hormones affect behavior through direct effects on brain differentiation and that behavioral differences must be located in the brain. It is argued instead that hormones coact and interact with other factors throughout development, that brain differences may result from as well as cause functional differences, and that hormone-based sources of sex differences may be located throughout the body and in the social surround. Directions for new research are suggested and implications for interpretation of human sex differences are discussed.     

Imitative learning in Japanese quail (Coturnix japonica) using the bidirectional control procedure

In the bidirectional control procedure, observers are exposed to a conspecific demonstrator responding to a manipulandum in one of two directions (e.g., left vs. right). This procedure controls for socially mediated effects (the mere presence of a conspecific) and stimulus enhancement (attention drawn to a manipulandum by its movement), and it has the added advantage of being symmetrical (the two different responses are similar in topography). Imitative learning is demonstrated when the observers make the response in the direction that they observed it being made. Recently, however, it has been suggested that when such evidence is found with a predominantly olfactory animal, such as the rat, it may result artifactually from odor cues left on one side of the manipulandum by the demonstrator. In the present experiment, we found that Japanese quail, for which odor cues are not likely to play a role, also showed significant correspondence between the direction in which the demonstrator and the observer push a screen to gain access to reward. Furthermore, control quail that observed the screen move, when the movement of the screen was not produced by the demonstrator, did not show similar correspondence between the direction of screen movement observed and that performed by the observer. Thus, with the appropriate control, the bidirectional procedure appears to be useful for studying imitation in avian species.     

A role for ovarian hormones in sexual differentiation of the brain

Historically, studies of the role of endogenous hormones in developmental differentiation of the sexes have suggested that mammalian sexual differentiation is mediated primarily by testicular androgens, and that exposure to androgens in early life leads to a male brain as defined by neuroanatomy and behavior. The female brain has been assumed to develop via a hormonal default mechanism, in the absence of androgen or other hormones. Ovarian hormones have significant effects on the development of a sexually dimorphic cortical structure, the corpus callosum, which is larger in male than in female rats. In the females, removal of the ovaries as late as Day 16 increases the cross-sectional area of the adult corpus callosum. Treatment with low-dose estradiol starting on Day 25 inhibits this effect. Female callosa are also enlarged by a combination of daily postnatal handling and exogenous testosterone administered prior to Day 8. The effects of androgen treatment are expressed early in development, with males and testosterone-treated females having larger callosa than control females as early as Day 30. The effects of ovariectomy do not appear until after Day 55. These findings are more consistent with other evidence of a later sensitive period for ovarian feminization as compared to androgenic masculinization.     

Discriminating the sex of conspecifics by male Japanese quail (Coturnix coturnix japonica).

How male Japanese quail (Coturnix coturnix japonica) discriminate the sex of conspecifics at a distance was investigated by testing subjects with male and female stimulus birds on the other side of a small window after opportunities to copulate with females and again after repeated exposures to males in the absence of copulatory opportunity. Time spent near the window, frequency of window approaches, duration of window visits, rate of walking near the window, line crossings outside the window area, pecking the window, and crowing were measured. Subjects responded similarly in the presence of male and female stimulus birds during the first test block but discriminated the sex of conspecifics after noncopulatory exposures to males. The discrimination was evident in less locomotion and less crowing in the presence of females as compared with males and, as predicted by a discrimination learning hypothesis, developed largely through a change in responding to males.     

Contextual conditioning and the control of copulatory behavior by species-specific sign stimuli in male Japanese quail

Three experiments were conducted to identify species-specific sign stimuli sufficient to elicit copulatory behavior in male Japanese quail and to determine how learning is involved in the control of behavior by these sign stimuli. In Experiment 1, sexually experienced subjects were tested for copulatory behavior with a live female quail and with a model consisting of a female quail's head and neck mounted in front of a foam pad. Comparable levels of copulatory behavior were observed in the two tests, indicating that static visual cues provided by a female quail's head and neck are sufficient to elicit copulatory behavior in this species. Experiment 2 showed that male birds that previously received numerous opportunities to copulate with a live female quail in the test situation were significantly more likely to copulate with the head + neck model than were sexually inexperienced subjects. Experiment 3 showed that prior sexual experience with live quail facilitated responding to the head + neck model only if the sexual experience was provided in the same place where subjects were later tested with the model. This last finding suggests that sexual experience facilitates control of copulatory behavior by species-specific sign stimuli through contextual conditioning. Contextual conditioning may lower the threshold for sexual behavior with the result that a stimulus as impoverished as an immobile model containing only the head and neck of a female quail becomes sufficient to elicit normal levels of copulatory behavior. The results are also discussed as an example of conditioned stimulus facilitation of responding to an unconditioned stimulus.     

Sexual Pavlovian conditioned approach behavior in male Japanese quail (Coturnix coturnix japonica)

A localized visual stimulus presented immediately prior to access to a female conspecific stimulated approach behavior in male Japanese quail after several conditioning trials. Development of this conditioned approach behavior was observed with two different types of signal lights, 10-s and 30-s signal durations, large and small experimental chambers, and with male birds housed continually in the conditioning chambers or only placed in the chamber for brief daily sessions. Conditioning also resulted in shorter latencies to initiate copulation in males given access to a female following the signal light, in comparison with males that received access to a female unannounced by the light. Although some aspects of the conditioning experience were retained over a 6-week interval, some loss of the behavior was also observed. The conditioned behavior also decreased with repeated extinction trials, during which the signal light was presented in the absence of access to a female conspecific. The results are discussed in relation to other aspects of the social behavior of Japanese quail and other studies of sexual conditioning.     

Genetic and experiential manipulation of fear-related behavior in Japanese quail chicks (Coturnix coturnix japonica)

We examined effects of environmental enrichment and regular handling on fear-related responses in chicks of Japanese quail (Coturnix coturnix japonica) selected over several generations for short or long tonic immobility (STI and LTI, respectively). STI chicks froze less, vocalized and walked sooner and more in an open field, emerged sooner from a hole-in-the-wall box, and showed shorter TI reactions than did chicks of the LTI line. Similarly, environmental enrichment reduced silence and inactivity in the open field, accelerated emergence, and attenuated TI. Regular handling promoted open-field vocalization and reduced the duration of TI but exerted no other significant effects. Principal component analysis showed that the responses in the 3 tests were not independent, which implies that they measured the same underlying factor. The genetic and experiential manipulation of stimulus-specific fears and of general fearfulness is discussed.