Showing papers in "Behaviour in 1984"

Syntactic Structures in the Vocalizations of Wedge-Capped Capuchin Monkeys, Cebus Olivaceus

Abstract: Capuchin monkeys, Cebus olivaceus, combine different types of calls to form compound calls. These compound calls are syntactically organized (i. e. , there is a predictable ordering of call types in the compound call). The analysis of the syntax of animal communication necessarily includes: (a) Accurate classification of types of calls, and a demonstration that calls that occur both alone and in compound calls are structurally similar. (b) Description of the syntactic rules generating compound calls or call sequences, and classification of types of compound calls or call sequences. (c) Examination of the social circumstances or contexts in which both single and compound calls occur. I followed these steps using a large sample of Cebus olivaceus calls, recorded in riparian gallery forest in central Venezuela. The calls were initially screened using a real-time spectrum analyzer, and a group of structurally related call types was selected for further analysis. Temporal and frequency characteristics of 868 of these calls were measured from sound spectrograms produced on a sound sonograph. Call classification involved first defining a very large number of possible call types on the basis of these characteristics, and then using a discriminant analysis to identify which types should be lumped together. A stepwise procedure was followed, using only calls which occurred singly, until five call types (squaws, chirps, trills, whistles, screams) were statistically separable. Two of these types (trills, whistles) showed considerable within-type variation and were further subdivided into four variants each. Discriminant analysis was then used to demonstrate structurally similarity between calls produced singly and those in compound calls. Social circumstances were defined using similarities in the vocalizer's actions, arousal, orientation to and distance from the presumed receiver. Use of call types, when given singly, covaried predictably with social circumstances and presumably with the internal state of the vocalizer. Different calls expressed different internal states on a continuum from contact-seeking to contact-avoiding. Use of trill and whitle variants also covaried with social circumstances. Different variants expressed different states on a continuum from affiliation or submission to aggression. Combinations of internal states, in theory, might be expressed as intergradations or intermediates between different call types. However, such intermediate states are often coded syntactically. Syntactically organized compound calls accounted for 38% of the total sample. The distribution of social circumstances in which compound calls are given was intermediate between the distributions of the constituent call types, which presumably indicates an intermediate internal state. Compound calls are generated by syntactic rules closely analogous to lexical rules of human language. Specifically they act like compounding rules that combine two lexical entries to form a third. They are not analogous to the grammatical rules that generate human sentences.

Information Exploitation By Downy Woodpeckers in Mixed-Species Flocks

Abstract: Downy woodpeckers (Picoides pubescens) benefit from foraging in mixed-species winter flocks by decreasing their vigilance level and increasing their feeding rate. I investigated one mechanism, auditory cues, downy woodpeckers use to obtain information on the presence of other flock members and potential predators. Experiments with predator models and with recorded alarm calls and contact calls from flock members yielded the following results. Downy woodpeckers use the contact calls of other flock members to assess the presence of flocks members. Woodpeckers foraging alone but with the recorded contact calls of flock members showed lower vigilance levels and higher feeding rates than woodpeckers foraging alone with no recordings or with the control recordings. Woodpeckers respond to the other species' alarm calls as an indication of potential predators and also to their contact calls as an all clear signal afterwards. Downy woodpeckers decreased their vigilance levels and resumed foraging faster when the contact calls followed the presentation of predator models or alarm calls than when these were presented alone.

Changes in Territorial Defense Produced By Changes in Circulating Levels of Testosterone: a Possible Hormonal Basis for Mate-Guarding Behavior in White-Crowned Sparrows

Abstract: Circulating levels of testosterone in male white-crowned sparrows increase when their mates are sexually receptive. Two experiments were conducted to test the hypothesis that this increase in circulating levels of testosterone results in an increase in the intensity of male territorial defense. The first experiment demonstrated that males with sexually receptive females are more aggressive than males with nonreceptive females under laboratory conditions. The second experiment, conducted in the field, confirmed the laboratory finding and also demonstrated that experimental elevation of plasma levels of testosterone results in increased territorial defense. Thus, male territorial behavior in white-crowned sparrows appears to be regulated by changes in circulating levels of testosterone. The fact that this results in males being most aggressive when their mates are sexually receptive suggests that this response functions as mate-guarding behavior.

Factors Affecting Calling Behaviour in Field Crickets, Teleogryllus and Gryllus (Age, Weight, Density, and Parasites)

Abstract: The duration of calling by male acoustical insects should reflect the selective forces of mating success and longevity. Nightly calling durations were studied in the field crickets Gryllus integer, G. pennsylvanicus, G. veletis, and Teleogryllus africanus. Immediately after the final molt, males were placed in individual jars in the laboratory. Jars were monitored electronically for the production of calling song. Males started calling at 4 to 7 days on average in each species, and there were no significant changes in duration of calling with increasing age. G. integer was also studied in a large outdoor arena. Arena males first called at approximately the same age as males in the laboratory, and the duration of calling did not change with age. Onset of first calling followed initial production of the spermatophore by a few days in separate samples of each species. Absence of ontogenetic changes in the amount of calling demonstrates that calling and satellite males in field populations of G. integer do not result from age differences. Mean calling duration per night was determined for each male, and there was no difference in mean calling duration with male weight in any species in the laboratory, or G. integer in the arena. G. integer called significantly less on average than the other species. Individual calling durations in G. integer were highly skewed, whereas distributions of the other species were normal in shape. Reduced calling in G. integer may result from the attraction of acoustically orienting parasitic flies, Euphasiopteryx ochraces, to the calling song of this cricket species. Coefficients of variation demonstrated that G. integer is more variable in acoustical behaviour than the remaining species, an observation confirmed by previous field studies.

Mother-Infant Interaction and Behavioral Development in Southern Right Whales, Eubalaena Australis

Abstract: A quantitative study of infant behavioral development and mother-infant interaction in individually identifiable southern right whale pairs was conducted from August to December 1979 at Peninsula Valdes, Argentina. A period of rapid travel soon after birth is hypothesized to develop calf swimming competence, to enhance the ability of the thin, nonbuoyant calf to rise to the surface to breath, and to hinder detection by predators. Subsequent slowing of travel at 3-4 weeks of age leads to an increase in resting by the mother and an increase in play by the calf. Calf play is centered around the mother and may function to develop motor skills in behaviors useful in social, reproductive, and other contexts as an adult, though in play, calves exaggerated behaviors and combined them in ways different from adult behavior. Days before departing from the nursery area, rapid travel again predominated, presumably functioning to prepare mother and calf for the subsequent migratory period. Nursing comprised about 5% of calves' diurnal behavior throughout the season but the length of individual bouts increased with calf age. The mothers' needs to conserve bodily reserves during their 4 month fast at this time may conflict, in terms of individual reproductive strategies, with the calves' needs to develop motor abilities through energy consumptive play. Commencement of migration appears independent of calf age or size and is probably spurred by seasonal factors. Some yearlings and their mothers return to Peninsula Valdes and separate from each other there.

Loud Calls of the Gibbon (Hylobates Lar): Repertoire, Organisation and Context

Abstract: We describe and illustrate with sonograms the loud calls of a monogamous, territorial ape, the lar gibbon (Hylobates lar). We attempt an overview of its repertoire of loud calls, their organisation, contexts and functions. The description is based on a two year study of a wild population in Khao Yai National Park, Thailand. We distinguish seven classes of call bout: male solo, male dispute calls, female solo, normal duet by bonded pair, ooaa duet (similar to normal duet, but more infectious to other groups), disturbed calls and contact calls. The organisation of the normal duet is described in detail, showing the coordination of the sexes, the development of the male part through the call bout, and the presence of individual and pair differences. The discussion considers the possible functions of duets, of male solos, and of disturbed calls given in reaction to man.

Ecological Constraints On the Social Development of Vervet Monkeys

Abstract: 1. Immature animals from three social groups of vervet monkeys (Cercopithecus aethiops) living in adjacent territories were observed in Amboseli National Park, Kenya. Measures of diets and food densities suggested that food quality and distribution differed both between the groups and between the dry and wet seasons, such that the dry season was a period of low food quality, and Group A had the lowest food density. 2. Seasonal differences in dietary quality and the time spent feeding produced seasonal differences in the rates of high energy social interactions: play, aggression, and competition. 3. Differences between groups in food availability and quality affected rates of social interactions such that Group A generally had the lowest frequency of interactions. Both between groups and between seasons, low food quality reduced the frequency of interactions and increased the time spent feeding. 4. Play rates were shown to be highly responsive to the energy estimated to be available from the diet during the different seasons such that play was eliminated from the immature social repertoire during the stressful dry season. 5. The time course of weaning also appeared to be influenced by seasonal and inter-group differences in habitat. Few females gave birth in consecutive years, and many suckled their infants into the second year of life. Stressed females weaned infants earlier. It is suggested that prolonged investment is a response to environmental variation and plays an important role in female reproductive strategies. 6. It is suggested that the immatures in these groups maximised the time and energy available for different types of social interactions in a different way in each season and in the different groups. This social flexibility may be viewed as part of an adaptive complex of behaviour during the immature stage of a life history.

Vocal Communication in a Neotropical Treefrog, Hyla Ebraccata: Aggressive Calls

Abstract: We studied the aggressive calls of Hyla ebraccata in Panama by recording natural interactions in the field and by playing recordings of natural and synthetic calls to males. Aggressive calls of this species had higher pulse repetition rates than advertisement calls and often were much longer. Aggressive calls also were much more variable in introductory note duration, pulse rate, rise time, and the number and structure of click notes. Pulse repetition rate was negatively correlated with the duration of the introductory note, as were the number of click notes in the call and the number of pulses in each click. In natural encounters, the duration of introductory notes increased as the distance between interacting males decreased. Males gave aggressive calls in response to playbacks of both advertisement and aggressive calls, but aggressive calls were much more effective in eliciting such responses. The proportion of aggressive calls and the duration of introductory notes generally increased with increasing playback intensity. Playbacks of synthetic calls which varied in pulse repetition rate and rise time showed that a high pulse repetition rate was the most important feature in eliciting aggressive responses from males, but rise time also was important when calls had fast pulse rates. The aggressive calls of this species appear to be a graded signaling system, the first to be documented in amphibians.

The Development of Mate Choice in Zebra Finch Females

Abstract: SONNEMANN & SJOLANDER (1977) found that zebra finch females raised by their own species (Zz females) differ in mate preference from females raised by Bengalese finches (Zb females) when given the choice between a Z male and a B male Their data also showed an own species bias (Zz females strongly preferred Z males, whereas Zb females showed about equal interest in Z and B males) Several authors mentioned the existence of a preference for species-specific characteristics independent of early experience (a so called 'innate' preference) as a cause for an own species bias This conclusion can be doubted for theoretical and methodological reasons and the question for the processes leading to an own species bias in zebra finch females seems completely open We investigated several possible causes of the own species bias Our experiments suggest that the final preference in Z females may be influenced by three independent processes First, visual stimuli are involved Information on these seems to stem exclusively, or at least largely from parental influence No initial preference for visual characteristics, independent of experience with Z or B has to be assumed Second, experiments indicate that a preference for actively courting males is present The process underlying this is unknown but seems independent of the one giving rise to a preference for visual stimuli Third, during the period between raising and testing (during which the females were visually isolated) the preference changes with age Here too, the underlying process is unclear Several possible causes for this change are discussed The process underlying it is probably different from the other two Altogether the results indicate that the own species bias may be the result of several independent developmental processes, which in combination led to a bias in testing

Vigilance and perception of flock size in foraging house sparrows (Passer domesticus L.)

Abstract: Perception of flockmates is clearly important if individuals' vigilance behaviour depends as much on the behaviour of other individuals as on the flock size. We attempted to evaluate the importance of flockmate perception in the scanning behaviour of free-living house sparrows Passer domesticus by observing them at an artificial feeder. Typically, sparrows would await on an adjacent wall, where they could see all the birds in the feeder, before hopping down to forage. Individuals' inter-scan time increased with flock size, but when a barrier was placed across the feeder, preventing sparrows in the feeder from seeing the other side, individuals scanned according to the number of visible sparrows, rather than the total number in the feeder. When two smaller feeders were placed at different distances apart, individuals greater than 1.2 m apart scanned independently of each other.

The Influence of Social Relations On the Development of Species Recognition in Zebra Finch Males

Abstract: The influence of social relations on the development of species recognition ('sexual imprinting') in zebra finch (Z) males was examined This was done with Z males raised by mixed pairs of Z and Bengalese finches (B)(♂Z♀B or ♀Z♂B) During rearing, the behaviour of parents and sibling towards the young Z males was measured Z males raised by mixed pairs were usually exposed to more parental behaviour, contact behaviour and aggression by Z (parent and sibling) than by B These males also preferred a Z over a B female later on, which might be a consequence of differences in behavioural interactions with Z and B In a series of experiments the amount of different behaviour patterns shown by the Z parents towards young Z males was decreased This led to a shift from Z to B in the later preference of these males, in spite of the fact that 'visual exposure' to Z was maintained as much as possible Influence of the sibling was examined by comparing the preference of Z males raised with a B sibling with that of Z males raised with a conspecific sibling The effect of the sibling on the later preference, if any, appeared to be marginal to that of the parents Preference differed between males raised by ♀ Z♂B pairs and males raised by ♂Z♀B pairs, the latter being more B directed Experiments indicate that this difference is most likely due to lack of familiarity with female Z characteristics in males raised by ♂Z♀B pairs The results strongly suggest that behavioural interactions between a young Z male and other birds, rather than visual exposure only, influence the later preference of this male Several mechanisms which might underlie this effect on the developmental process are discussed No initial preference for Z characteristics has to be assumed to explain that Z males raised by mixed pairs normally develop a Z directed preference

Local and Regional Variations in Chaffinch Song and the Question of Dialects

Abstract: Within an area chaffinch songs show considerable variation, but most of them fall clearly into types Three human observers showed a high degree of agreement about classifying songs from sonagrams, and cluster analysis by computer using measures of frequency and timing gave very similar results for three-phrase trill songs, though less good for those with four phrases It is suggested that songs fall into types, not because variation is inherently discontinuous, but because accurate learning requires only a small number of repetitions of a song to be heard With many fewer than this the song is learnt so inaccurately that it forms a new type, and only in the unlikely event of an intermediate number being heard will the copy be hard to classify Despite the variation within an area, chaffinch songs in different parts of the British Isles have very similar general characteristics There is a tendency for songs from Orkney to have fewer trill phrases and a longer end-phrase than those from Sussex, but few other significant differences were found and discriminant analysis by computer was only 69% successful at best in classifying songs into the correct groups While several song types in an area may share features not found in another place, because song types are derived from each other through cultural evolution, there is no evidence to suggest that all the songs in one area have any feature distinct from those in others, as the word dialect might imply Instead it seems that the various song types within an area get close to exploring the limits of the variability of song found in the country as a whole

The Effects of Bidirectional Selection for Social Dominance On Agonistic Behavior and Sex Ratios in the Paradise Fish (Macropodus Opercularis)

Abstract: A population of paradise fish (Macropodus opercularis) was subjected to five generations of bidirectional selection for social dominance in order to investigate correlated changes in agonistic behaviors. In addition to the high and low dominance lines (HD and LD respectively), a third dominance line was created through selection for individuals closest to the median in dominance success. The MD line provided standard opponents for members of the other two dominance lines and served as a control for inbreeding effects. The response to selection was asymmetrical. After five generations of selection the LD line had diverged significantly from the MD line, but the HD line had not. None of the three factors known to cause an asymmetrical response to selection (directional gene frequencies, directional allelic dominance and inbreeding depression) can account for the response to selection found here. The divergence of the HD and LD lines with respect to dominance success was not accompanied by any changes in the measures of aggressiveness. The F-5 generation of the HD and LD lines did not differ significantly for any of the measures of aggressiveness used here, indicating that social dominance and aggressiveness are not intimately related. An alteration in the sex ratio of the HD line was an unanticipated byproduct of selection. The F-5 generation of this selection line contained an overwhelming preponderance of males. Interpretation of these results is complicated by the fact that environmental factors such as temperature and the degree of crowding probably influence sexual differentiation in this species. The social crowding factor, in particular, was found to be important and was investigated in a preliminary way. For all three dominance lines it was found that as crowding increased, so did the proportion of females in a brood. Fish raised in physical isolation showed a strong tendency to become males. These results suggest that sexual differentiation is socially mediated. Within a given brood, fish of high dominance status tended to become males and fish of low dominance status tended to become females. The results from the isolation-reared fish indicate that it is not dominance per se that promotes maleness, but rather, the condition of being undominated. Under uncrowded conditions an individual is, on average, dominated by fewer fish than under crowded conditions. Above and beyond this density related trend in the sex ratios, however, there were significant between-the-line differences. The HD line showed a greater proportion of males than the other dominance lines, over all density conditions. It appears that selection for high social dominance constituted selection for maleness. This response to selection indicates a continuum of genetic sex in this species and a polyfactorial mode of inheritance. The alteration in the sex ratios might also explain the asymmetrical response to selection for social dominance, in that the HD line did in fact exhibit a greater proportion of dominant fish, though not a greater proportion of dominant males, than the other two dominance lines. As such, the asymmetrical response to selection would be an artifact of the measuring procedures.

Vocal Mimicry in Starlings

Abstract: Starlings imitate a variety of avian species and have a repertoire of about 15-20 distinct imitations. They also imitate a few sounds other than those of wild birds. The calls of abundant species, calls that are simple in frequency structure and calls that show little amplitude modulation are preferentially imitated. There are local dialects of mimicked sounds. These results are discussed in relation to possible functional explanations of vocal mimicry. Explanations which involve the deceit of other birds are rejected. It is concluded that the understanding of vocal mimicry is probably not distinct from the understanding of the rest of the song.

Great tits and giving-up times: decision rules for leaving patches

Abstract: In this paper I examine the hypothesis that animals employ simple decision rules in exploiting patchily distributed food. This idea arises from the supposition that animals probably cannot compute the optimal patch residence time in the same manner that is calculated in optimal foraging models. Instead they may only approximate the optimal solution using a simple, robust rule-of-thumb. I considered three rules-of-thumb that great tits foraging in a simple experimental habitat may use: a number expectation, a time expectation, and a giving-up time. The experimental habitat consisted of an operant patch in which great tits had to search for food by hopping on a perch. The probability of reward declined for successive patch hops according to a predetermined stochastic schedule. In order to maximize food intake, the great tits had to occasionally leave the patch and fly across the experimental room to reset the reward schedule by hopping on a second perch. Three different lines of investigation were followed to test which of the three departure rules were employed: (a) a statistical analysis showed that there was a strong tendency for great tits to leave the patch only after several successive hops had gone unrewarded; (b) a computer simulation showed that a simple giving-up rule could produce a distribution of patch residence times similar to that observed; (c) an experiment in which the reward schedule was manipulated, successfully altered the patch residence times in accord with predictions made on the basis of a giving-up time rule. Thus, all three tests produced evidence in favour of the giving-up time rule. Although the great tits used a giving-up time rule, a residence time would have resulted in a higher rate of intake. One potential explanation of this apparent error is that the natural food of great tits has a clumped distribution, to which a giving-up time is better suited than a residence time rule. Finally, I point out that the observed giving-up time was much more variable than might be expected if it were adjusted solely in response to the habitat rate of intake. I suggest some hypotheses to explain this large variation.

The significance of song variation in a population of Darwin's finches

Abstract: Males of Geospiza conirostris, the large cactus finch, on Isla Genovesa, Galapagos, sing a single, precisely copied song. There are two song types in the population, and these are sub-divided into 3 and 5 discrete song sub-types respectively. Adult males sing only one song sub-type throughout life. Sons sing the same song sub-type as their fathers' and do not copy the songs of either natal or breeding territory neighbours. Significantly more of the males holding territories with neighbours of unlike (heterotypic) song type obtain a female than males in territories with no heterotypic neighbour. Pairs in territories with a heterotypic neighbour fledge significantly more young than do pairs in territories with no heterotypic neighbour. Significantly more of those young born on territories with a heterotypic neighbour, that survive to become adults, obtain a mate, than do those surviving young born on territories with no heterotypic neighbour. The data are consistent with the hypothesis that the relative greater importance of song for species recognition in this population has made it advantageous for males to have a single, short, distinct, precisely copied and stable song. The necessity for recognizing both song types as conspecific has produced a unique mating pattern which favours pairs in territories with a heterotypic song neighbour. This allows young to associate visual and auditory cues of father and neighbouring male during the short period of imprinting. A small effective population size, combined with the observation that no female has been known to mate with a male of the same song sub-type as her father's, suggests a possible kin recognition system to avoid inbreeding.

The Responsiveness of Newly Born Clun Forest Lambs To Odour Sources in the Ewe

Abstract: Two groups of newly born lambs, twelve ("suckled" lambs) having been fed by the mother and aged between 3 and 21 h, and twelve ("unsuckled" lambs) taken at birth with minimal olfactory experience of the dam, were tested with the smell of three substances taken from the mother and three taken from an alien ewe. The substances were inguinal wax, wool and milk. Changes in heart and breathing rates and in behavioural activity were used as indices of the lambs' response. Results showed that lambs in both groups responded most markedly to the smell of wax. Behavioural responses consisted of head movements, oral activity and bleats and in unsuckled lambs were given significantly more to the smell of maternal, than of alien wax. Unsuckled lambs responded more to all six odour sources than did suckled lambs. In unsuckled lambs the rate of breathing rose significantly during stimulation with the smell of maternal wax and this response was also significantly different from that given by unsuckled lambs to alien wax. In suckled, but not unsuckled, lambs there was a significant rise in the heart rate during and after stimulation with maternal wax, but not in response to any other odour source. Results are discussed in terms of "teat-seeking" behaviour in newly born lambs and the question whether the unsuckled lambs' capacity to discriminate their own mother's from alien wax depends on prenatal olfactory experience.

Relation of Behavioural Activity Rhythms To the Changes of Day and Night. a Revision of Views

Abstract: All free-living animals have their lives divided into periods of rest and of activity, and these periods are tied to the changes of ambient factors recurring through the diel. These changes are essentially caused by the changing altitude of the sun which divides the diel into day and night with all the associated phenomena. Of these variable factors, the illumination is by far the most important one. With very few exceptions, all free-living animals are exposed every single diel to the change from light to darkness; a change not only of enormous amplitude but also, and perhaps still more important, of inexorable regularity. Temperature, humidity, and wind fluctuate too in accordance with the sun's altitude, but they depend also on other more complex factors such as displacement of airmasses, and are therefore, of secondary importance. The problem dealt with below is: By which mechanism does the changing altitude of the sun, that is the hours of the diel, determine the periodicity of behavioural activity through these factors.

Clasping Behaviour in Macaca Tonkeana

Abstract: Clasping behaviour was studied in two groups of Macaca tonkeana, one being confined in a cage, the other living in a half-hectare park. Five patterns have been distinguished: grasping the hindquarters, grasping, reaching around, embracing and hugging. Clasping may occur in three contexts: greeting, aggression and sexual harassment. There seems to be no direct relationship between context and pattern of clasping. However, there is substantial variation in form and context according to age- and sex-class. Females are the individuals mostly involved in clasps, being initiators as well as receivers; adult males also initiate numerous clasps but receive few. Adult and subadult males especially use grasping the hindquarters while other age- and sex-classes more often use reaching around. Clasping in aggression is more characteristic of females than males. Several behaviours may be associated with clasping. The accompanying behaviours are more frequent in initiator than in receiver. Clasp is often followed by social grooming, mount, wrestle or another clasp. The results of this study in Macaca tonkeana may be compared with information from other studies of non-human primate species. This allows one to draw several conclusions: 1. Frequency, form and distribution of clasping vary from one species to another. There is great variation in certain species, for instance, Macaca tonkeana. 2. Several behaviours usually accompany clasping and may modulate its meaning. 3. Clasping behaviour shows many similarities to mounting behaviour. Although these two behaviours have different origins, they have acquired similar social functions. 4. Clasping plays a prominent role in control of aggression. In Macaca tonkeana, this behaviour is especially used in appeasement (an individual receiving aggression clasps its aggressor during the aggression), reconciliation (an aggressor clasps its antagonist after the aggression) and non-agonistic protection (a third individual intervenes in an agonistic interaction by clasping the aggressor). Non-agonistic protection is an interaction which was until now described only in chimpanzees.

Age Differences in Foraging Behavior of the American Robin (Turdus Migratorius)

Abstract: Comparison of feeding behavior of adult and juvenile American robins (Turdus migratorius) revealed significant differences in several measures of feeding efficiency and success. Adult robins captured larger food items, made more captures per unit time, took fewer steps, and made fewer unsuccessful attempts. Juveniles took 136% as long to capture each food item and required 161 % as many steps as adults, obtaining 25% less food per unit time. During the 10 weeks of the study foraging efficiency fluctuated, apparently reflecting differences in food availability, and we were unable to detect any improvement in efficiency of juveniles relative to adults during the course of the study. Three spot-classes of juvenile plumage were defined, and are believed to reflect slight average age differences, but no difference in foraging efficiency could be detected between the classes, indicating that between about 3 and 5 months of age, improvement must be subtle. This documentation of age differences between adult and juveniles that have been independent 1 to 4 months points to the importance of skill acquisition in foraging behavior in altricial birds.

The "feed: drink" decision

Abstract: The "feed:drink" decision is investigated in an attempt to discover how internal and external factors interact in controlling behaviour. The problem is attacked from both a functional and causal perspective. A functional approach is used in suggesting how internal and external factors should interact if the animal is to achieve a maximally efficient regulation of internal state. Here, I rely on an optimality model proposed by SIBLY & MCFARLAND (1976). Predictions made by this model are discussed, and it is shown that results from published studies on feeding and drinking in Barbary doves are not consistent with this model. It is argued that this is because animals lack information about external factor levels. This information can only be obtained by assessing the consequences of their prior behaviour. A motivational model is proposed to account for this process. Simulation experiments are done in order to reveal predictions made by this model. These experiments mimic ones that were done using Barbary doves, and it is shown that the behaviour of this model agrees precisely with that seen in these birds. The model correctly predicts effects due to behaviour interruption and changes in food and water availability. The functional implications of this model are considered by comparing simulated behaviour sequences with sequences predicted by SIBLY & MCFARLAND'S optimality model. In certain situations, there is close agreement between simulated and "so-called" optimal sequences. For this reason, it is argued that the motivational mechanisms described are designed to service the goal that SIBLY & MCFARLAND assumed in generating their optimality model. The goal is to regulate internal state in a maximally efficient manner.

The "Feed:Feed" Decision: How Goldfish Solve the Patch Depletion Problem

Abstract: The "feed:feed" decision concerns the problem of how an animal chooses between various feeding activities. Optimal foraging theory fails to account for this decision-making process because it does not describe how animals obtain information about their feeding opportunities. The model discussed in this paper describes how this information is obtained and how it influences the "feed: feed" decision. The model is first described in a simplified form, the dynamic matching rule. This rule states that the animal allocates time to each patch in proportion to the number of rewards it recently obtained from each. In the case where food is available in different patches, it predicts a gradual development of preference for the better patch. Results from published studies where patch profitabilities remained constant are shown to support this prediction. The model is tested by examining how goldfish distribute their time between two patches, when these patches are depleted as a consequence of foraging. The model predicts that goldfish will first develop a preference for the initially higher density patch, but that a reversal in this development will occur once they deplete this patch below the other patch. The results are shown to support this model. Limitations of this simple model are subsequently discussed. It is shown to be a simplified version of HARLEY'S (1981) "relative payoff sum" rule. HARLEY'S model identifies two factors which interact in determining behaviour. One is an excitatory effect that results from feeding; the other describes what the animal has learned from previous experience. (The dynamic matching rule did not consider the latter effect). Predictions made by this model are also supported by the goldfish results. The functional implications of HARLEY'S model are discussed. It is shown that this model predicts equilibrium behaviour which closely approximates the optimal response. Thus, it describes how behavioural mechanisms are structured so that animals will forage efficiently. Finally, it is argued that this model, in its present state, describes the structure of a motivational control system. Learning processes appear as parameters in the model, the determinants of which remain to be identified.

Parental Division of Labor in a Monogamous Fish

Abstract: Both parents of the monogamous Texas cichlid (Cichlasoma cyanoguttatum) participate in offspring care and territorial defense. These activities are typically synchronized, with and without intruders being present, such that only one parent is away from the offspring. During the egg and wriggler stage, the male spends more time patrolling the territory while the female devotes more time to offspring care. During the fry stage, both parents tend to remain with the offspring. Either sex can rear the offspring in the absence of the mate. With the removal of the mate, the female's activities remain largely unchanged while the male (in the absence of the female) becomes female-like. It appears as if the male adjusts his responses according to the activity of the female.

Communication of Intentions in Agonistic Contexts By the Pigeon Guillemot, Cepphus Columba

Abstract: This observational study of communication behavior of the pigeon guillemot (Cepphus columba) in agonistic contexts studied two questions: (1) What factors influence the outcome of interactions between male territory owners and intruders? and (2) Is information about the signaller's intention contained in signals? Pigeon guillemots nest in rock crevices which they defend against conspecifics. Intruders tend to visit single birds on territories as opposed to pairs or unoccupied territories. Male territory owners give a long (mean = 85 sec) series of whistled notes, the Hunch-whistle display, and enter the nest crevice when a female visits. Males also Hunch-whistle "spontaneously" and females approach, enter the nest, and appear to inspect the male's nest-site. Mutual Hunch-whistles usually involve male owners and male intruders, and tend to occur soon after a bird occupies a territory. The outcome of interactions between male territory owners and non-mate intruders was independent of the intruder's sex. Intruders retreated without escalation occurring in 51 % of cases and the owner attacked in 2 % of the cases. Fights involving both birds were rare and tended to occur early in the breeding season when both males had spent time on the territory in the previous week. No injuries were witnessed in over 600 aggressive interactions. Territory owners won 21 of 23 fights with male intruders. Size and age did not appear to contribute to fighting success. A pay-off asymmetry in favor of owners best explains the dominance of owners over intruders. Analysis of behavior sequences using a three-dimensional contingency table revealed that displays were significantly associated with different responses by recipients and with different subsequent behaviors by the signaller. The response also had an effect on the displayer's subsequent behavior. Flight by recipients decreased the probability of subsequent attack by signallers but other, less predictable forms of interaction between response and subequent behavior also occurred. Territory intruders flew after 43 % of the occurrences of the Neck-stretched display; no owner display preceded attack more than 14% of the time. Variation in the length and frequency of Hunch-whistle notes reflect changing probabilities that the signaller will sit, move, or attack. The owner/intruder dichotomy best explains which bird attacks/flies in an interaction. Variability in the bird's vocalization provides information about when flight or attack will occur. Differences in costs associated with attack versus flight may explain why flight is potentially more predictable than attack.

Function of Manx Shearwater Calls in Mate Attraction

Abstract: Playback experiments were used to study the role of vocalization in mate attraction by Manx shearwaters, a nocturnal seabird. Pre-breeding birds were exposed to test calls of male and female shearwaters calling from the range of normal locations: above the colony as in a flyover call, on the ground in the colony, or from within the nesting burrow. Both female and male test calls increased the frequency of male calling but only male calls increased the frequency of female calling. These findings suggest that male calls 1) facilitated competing responses from other males that are attempting to attract females to their burrows and 2) stimulated calling in available females that require more directional information to find the advertising male. Male calling location, inside or outside the burrow, probably reflected a compromise between being audible to females and being susceptible to predation. Because the call was more widely broadcast, male test calls played from outside the burrow caused more females to land in the colony than the same call played from inside the burrow. However in a simultaneous choice test between a burrow and an outside male test call, males calling from inside did not lose females to the adjacent outside male. Thus calling from inside the burrow in an area where another male is calling outside maximized female attraction while minimizing risk of predation. The male call played from inside the burrow attracted as many females as a pair call from inside but the response of females to the pair was less sustained, indicating that duetting pairs-inhibited the response of unpaired females. Male and female calls emanating from above the colony suppressed the rate of female flyover calls suggesting that during this test condition other birds stopped calling in an attempt to orient to the source of the test call.

Extra-Territorial Movements of a Perennially Territorial Damselfish, Eupomacentrus Dorsopunicans Poey

Abstract: 1. Dusky damselfish, Eupomacentrus dorsopunicans spend the majority of their time in very small, perennial territories but long forays to other territories are common. 2. Adults living on discrete habitats often forayed to continuous habitats, and were lost more frequently during a six month census. 3. Continuous habitat occupants participated in more courtship activity. 4. Following experimental habitat disruption the number of forays increased prior to the establishment of new territories, thus demonstrating that foraying is associated with territorial reestablishment. 5. Territorial shifts are essential for perennially territorial individuals in inferior habitats, and foraying is apparently a territorial monitoring mechanism. Presumably, forays optimally time territorial shifts and reduce their inherent costs.

Helpers(?) At the Nest in the Mongolian Gerbil, Meriones Unguiculatus

Abstract: Mongolian gerbil families were observed in artificial burrow systems and the effects of the presence of juveniles and the number of 'underground' nest areas were noted. Juveniles interacted with infants and increased their time in the maternal nest during the rearing of the infants as did the fathers. Parents spent less time self-grooming and licking the infants if juveniles were present. The fathers appeared to act paternally mainly towards the juveniles but also supplied the "underground" area with food. These observations were congruent with the prediction that juveniles act as helpers at the nest. A second experiment, however, indicated that juveniles retarded the development of the infants, possibly by stealing milk. The parents appeared to minimise the detrimental effects that juveniles had on the development of the infants and yet ensured that the juveniles remain within the family group until they were old enough to fend for themselves. The number of nest areas had little effect on these social interactions.

Aggression, Copulation, and Differential Reproduction of Deer Mice (Peromyscus Maniculatus) in a Semi-Natural Enclosure

Abstract: This study was designed to analyze the interactions of priority of residence, strain, dominance, male capacity, and sperm competition in relation to aggression, copulation, and differential reproduction in deer mice (Peromyscus maniculatus). Males were wild-type or blonde mutants; females were of the recessive blonde phenotype. There were 20 replicates of a procedure entailing 7-day runs. One male was introduced into a seminatural enclosure on Day 1 and the second male on Day 3. Their interactions were sampled on Days 3-7. In addition, two estrous females were introduced for tests on Day 5 and 6. In the absence of females, levels of male-male aggression were lower than in their presence. Priority of residence led to increased levels of chasing by males. Limitations on male capacity were revealed as decreased numbers of ejaculations and chases in the second of the two tests with females. Dominance was established in 13 of the 20 runs; copulation occurred in 28 of the 41 tests. Dominant males achieved more ejaculations than subordinates. Males copulated with both females on 20 of 41 occasions, with most partner changes (but smaller percentage per opportunity) occurring within ejaculatory series. Females copulated on 44 of the 82 occasions and delivered a total of 30 litters. Determinants of differential reproduction were diffuse.

Social organization of small heterosexual groups of Green swordtails (Xiphophorus helleri, Pisces, Poeciliidae) under conditions of captivity

Abstract: Sixteen populations, each of four male and four female green 'swordtail fish, were ob­served in 54 litre tanks separated into two unequal volumes by a partition allowing swim­ming from one area to another only at the surface. Each population was observed on 2 4 occasions, making a combined total of 50 observation periods of 2 hours each. Chase right orders, spatial positions as well as several agonistic and epigamic behaviour units were noted during each period of observation. Males and females apparently form distinct hierarchies which are perfectly linear and transitive in 68% and 42% of the cases respec­tively. Some dominance structures are incomplete, but no intransitivity is noted. Alpha males are much more aggressive than their isosexual subordinates. In females, the fre­quency of aggressive behaviour appears to be more proportional to the social rank of the initiator, but the number of chases received from other females is the best indicator of rank in the female hierarchies. Alpha males are responsible for 80% of all sexual activity and have privilege to behaviour leading to insemination with a high probability in 85 % of the cases. Females are not courted according to their position in the female hierarchy, nor to their size. In the two compartment situation of the present study, which allowed spacing out and visual isolation of the individuals, the alpha males occupied the larger area of the aquarium in the company of the four females while the three subordinate males were restricted to the smaller area, unaccompanied by any females. This spacing out pat­tern emerged with neat regularity from the data and was apparently caused and main­tained by aggressive behaviour, especially by charges, initiated by the alpha male toward male rivals. However, it is not evident that the behaviour of the alpha male should be neatly qualified as territorial defence, since specific area linked dominance was never realized in the present study. The social scheme most readily applicable to the present social and spatial organization is the "one male to several females" system or monar­chistic male hierarchy, in which one male becomes very dominant over the others, oc­cupies the larger area and is also the sole individual to court the females and to attempt in­semination (haremic). These results support the sociobiological theorem that to dominate is to have priority of access to the necessities of life and reproduction.

Some Notes On Factor Analysis of Behavioral Data

Abstract: The use of factor analysis with behavioral data is examined critically Although there are good reasons to make wider use of factor analytic techniques in behavioral research, several important pitfalls should be avoided Samples should be of adequate size, both absolutely and relative to the number of variables analysed Variables should be reliable and devoid of scoring dependencies One should not allow the same components to appear in different ratio variables, difference scores and composites Variables and subjects should be carefully selected to represent a substantive design for the study Ideally this design should stem from empirically-based, well reasoned theory Careful thought should be given to the question of the number of factors to extract Rotation of factors should be based on the model reflected in the design for the study One should be wary of using mathematical-statistical indices with factor coefficients The correlation, as such, and the standard error for a correlation, do not have the same properties when applied to arrays of factor coefficients as when used with free-to-vary numbers