bluuebunny/crossref_metadata_2025 huggingface dataset:
Infanticide in Mountain Gorillas: New Cases and a Reconsideration of the Evidence
Authors: Watts David P.
Published: May 2010

Data on six cases of infanticide, one infanticide attempt, and one suspected infanticide in mountain gorillas (Gorilla gorilla beringei) are presented here for the first time. These and previously reported cases in the same population are analyzed in order to assess the circumstances and consequences of infanticide.

Most infanticides occur when infants' mothers are not accompanied by their group's mature male (usually because he has died). Infants in this situation are almost certain to be killed by unfamiliar males unless they are nearly weaned. Active defense of infants by females is ineffective, and females cannot avoid unfamiliar males for prolonged periods. In contrast, infanticide is rare — yet has been observed — in encounters between mature males. It is not associated with group takeovers and male eviction by extra‐group males, unlike the case in many other mammals. Demographic constraints and reproductive competition limit the occurrence of defensive coalitions between males. These factors, plus the high risks associated with male/male aggression, inhibit the occurrence of group takeovers by male coalitions. Infanticide shortens interbirth intervals and results in a high probability that a female will mate with the infanticidal male.

These findings support the sexual‐selection hypothesis for the evolution of infanticide and strongly support the argument that intersexual mutualism and intraspecific aggression have been central factors in gorillas' social evolution.
Toward a Resolution of the Paradox of Aggressive Displays: I. Optimal Deceit in the Communication of Fighting Ability
Authors: Bond Alan B.
Published: May 2010

One inference from game theory models of animal conflict is that adversaries should not inform one another about concealed components of their fighting ability. This poses a paradox for the customary ethological account of aggressive displays in that it is usually assumed that the primary function of such behavior is to make such information available. To resolve the paradox, I propose that the information in aggressive displays may not be strictly truthful, but may instead represent “optimal deceit,” a balance between the advantages of deceit or bluffing and the disadvantages of selecting for skepticism in the receiver. Numerical simulation of this model was performed to examine the effects of differences in fighting ability and in the risk of injury in an escalated conflict. The model converged on an equilibrium level of deceit, even when the receiver was ignorant of the average level of deception being employed.
Effects of Social Environment on Play in Squirrel Monkeys: Resolving Harlequin's Dilemma
Authors: Biben Maxeen
Published: May 2010

Yearling‐male squirrel monkeys (Saimiri sciureus) were paired with play partners either matched or different from them in age and/or sex. The frequency of play was maintained at equally high levels with both matched and mismatched partners. However, play between mismatched partners was marked by an unusually high incidence of nondirectional wrestling, a less threatening form of playfighting, and an increase in role reversal, suggesting that youngsters had considerable flexibility in the use of alternate strategies to sustain play activity with partners who were atypical for them. These results also attest to the robustness of play and its importance in the behavioral repertoire. The technique of restricting youngsters to atypical play companions is suggested as an effective means of manipulating play, with minimal disruption of other social experiences, for long‐term studies of the developmental impact of social play.
Smashing Energetics: Prey Selection and Feeding Efficiency of the Stomatopod, Gonodactylus bredini
Authors: Full Robert J. , Caldwell Roy L. , Chow Shong W.
Published: May 2010

The simplest prey‐selection model predicts that predators select prey to maximize energetic benefit and minimize handling time. We tested whether or not energetic indices predict stomatopod preference for prey. The energetic indices included: 1) the ratio of energetic return (mass of prey tissue, M) per unit handling time (feeding duration, T); 2) the ratio of energetic benefit (caloric value of prey tissue, E) to energetic cost (caloric value of energy expended, C); and 3) the ratio of net energetic benefit (caloric value of food minus the caloric value of energy expended, NE) to handling time.

Stomatopods, characterized by highly specialized raptorial feeding appendages, strike and smash the shells of prey such as snails. The prey‐capture strike is one of the fastest known animal movements. Stomatopods, presented with snail shells of three size classes (5–6, 8–9, 11–12 mm in length), preferred intermediate and small snails. Oxygen consumption increased an average 2.5‐fold above resting rates during feeding and increased linearly with strike frequency. The energetic cost per strike was 1.6 ± 0.2 μl O2. Stomatopods obtained more snail tissue from smashing larger snail shells. However, longer handling times were required to open shells of greater size. To obtain snail tissue, stomatopods struck larger shells a greater number of times. Strike frequency (0.72 strikes/min) was independent of shell size. The amount of snail tissue obtained per strike (0.044 mg/strike), M/T, NE/T, and E/C were all independent of snail size. The mean energetic benefit per strike (0.23 calories/strike) was 13‐fold greater than the energetic cost per strike (0.017 calories/strike). Energetic cost, energetic benefit and handling time appear not to be the sole variables that explain stomatopod prey selection.
Begging Behavior in Budgerigars
Authors: Stamps Judy , Clark Anne , Arrowood Pat , Kus Barbara
Published: May 2010

Five hypotheses about relationships between begging rates, feeding rates and other variables were investigated in captive budgerigar nestlings from 23 days post‐hatch to fledge date (Period 4). Within families, nestlings that begged more frequently during Period 4 were fed more often by their parents, but there was no indication that nestling weight on day 23 was related to begging rates in the subsequent growth interval. Instead, last‐hatched nestlings begged more than their older siblings. Last‐hatched nestlings were not “undersized” at the beginning of Period 4 relative to their siblings, and they experienced less competition than their siblings had at comparable ages. Even so, last‐hatched budgerigars begged more often, were fed more often and fledged at heavier weights than their older nestmates.

Across families, there was a strong positive relationship between average Period 4 begging rate and average parental feeding rate, but this relationship was much weaker when brood sex ratio was taken into account: female‐biased broods had much higher begging and feeding rates than male‐biased broods. Brood size was related to begging, with higher ratios of begging to feeding rates for family members than for single nestlings.

Taken together, these results suggest that relationships between feeding and begging behavior in budgerigars are more complex than theoretical models have suggested. More studies of avian begging and feeding patterns are required before we can generalize about the control of parental food allocations in birds.
Integration of “Innate” and “Learned” Components within the IRME for Mussel Recognition in the European Bitterling Rhodeus amarus (Bloch)
Authors: Heschl Adolf
Published: May 2010

The European bitterling (Rhodeus amarus Bloch) practises a rather unusual method of spawning by using the favorable conditions in the gills of a living freshwater mussel (genera Unio and Anodonta) for the embryonic development of its fry. The capacity of mussel recognition was studied in inexperienced individuals with the aid of simultaneous preference tests in which pairs of dummies with increasing similarity to mussels were presented to the animals. The frequency of mussel‐referred motor patterns, which were supposed to be species‐specific (Wiepkema 1961), supplied the evaluation criterion. The results revealed a hierarchy of effectiveness within the class of relevant stimuli and showed certain effects of additivity typical of an Innate Releasing Mechanism or IRM. By far the most effective stimulus consisted in the specific smell of the mussel which is composed of at least three constituents (protein, hyaluronic acid, ammonium). The water flow itself, produced by the mussel in order to maintain nutritive and respiratory functions, was effective depending on its velocity (3 < v < 12 cm/s), its orientation (suction produced no effect), its direction (vertical > horizontal) and the shape of its field (oval). Within the visual modality only two simple perceptory patterns could be detected (dark spot on a clearer surface, straight horizontal edge), but the visual shape of the mussel as a whole was ignored by inexperienced individuals. Nevertheless the bitterlings are able to learn the shape when exposed to a living mussel and, in addition, it was even possible to condition the animals to an artificial object (inverted pot of clay) by using the mussel‐smell flow as a reinforcing stimulus. The final discussion deals with the question of whether it is possible to interpret these “innate” respectively “learned” components of the IRME as sensory counterparts of behavioral structures which simply serve different functions by referring to correspondingly different sectors of the environment. In such a case the epistemological dichotomy regularly associated with the notions of “innate” (= “pre‐given phylogenetical knowledge”) and “learned” (= “cognitive increase during ontogeny”) would suffer incisive questioning.
Toward a Resolution of the Paradox of Aggressive Displays: II. Behavioral Efference and the Communication of Intentions
Authors: Bond Alan B.
Published: May 2010

An inference from game‐theory models of animal conflict is that adversaries should not inform one another about their level of aggressive motivation. This poses a paradox for the traditional ethological account of graded aggressive displays because it is usually assumed that the adaptive significance of these behavior patterns lies in their making such information available. To resolve the paradox, I propose that communication is only an incidental effect of displays, and that their primary adaptive function is regulation of the intensity of aggressive encounters through positive feedback on aggressive motivation, a process termed “behavioral efference.” Evidence in support of this hypothesis is drawn from studies of human facial expression, aggressive catharsis, and operant conditioning of aggressive behavior. Implications of the hypothesis and suggestions for further work are discussed.
Nest Entrance Marking with Colony Specific Odors by the Bumble Bee Bombus occidentalis (Hymenoptera: Apidae)
Authors: Foster Robin L. , Gamboa George J.
Published: May 2010

We investigated the ability of naturally foraging female bumble bees (Bombus occidentalis) to recognize their nest entrance in the field. In a blind binary‐choice paradigm, females discriminated between nest entrances tipped with caps from their own nest entrances and entrances tipped with caps previously associated with foreign heterospecific or foreign conspecific colonies. Washing caps in organic solvents eliminated the manifestation of this nest‐entrance recognition and significantly decreased the episodes of antennating caps. These results indicate that bees deposit colony‐specific chemicals on nest entrances that are later perceived via contact chemoreception. Females treated foreign heterospecific and foreign conspecific caps similarly, suggesting that bees may not assess or respond to the degree of similarity between their own colony odor and a foreign colony odor.
The Response of Asterropteryx semipunctatus and Gnatholepis anjerensis (Pisces, Gobiidae) to Chemical Stimuli from Injured Conspecifics, an Alarm Response in Gobies
Authors: Smith R. Jan F.
Published: May 2010

Asterropteryx semipunctatus, a small Indo‐Pacific gobiid fish, shows reduced movement and increased bobbing behaviour in response to water that has contained injured conspecifics. This response is qualitatively similar to its response to water that has contained a predator, the lizardfish Synodus variegatus, or to visual contact with a predator. This alarm reaction does not occur in response to water that has contained uninjured A. semipunctatus, injured mollies, Poecilia mexicana, or injured Gnatholepis anjerensis, a sympatric goby. G. anjerensis does not show an alarm response to chemical stimuli from injured conspecifics or from injured A. semipunctatus.
Recruitment and Other Communication Behavior in the Ponerine Ant Ectatomma ruidum
Authors: Pratt Stephen C.
Published: May 2010

The ponerine ant Ectatomma ruidum, though previously reported to possess only rudimentary recruitment ability, was found to lay chemical trails for mass recruitment to rich or difficult food sources. The pheromone originates from the Dufour's gland, a new source of trail pheromones in the primitive ant subfamily Ponerinae. During nest emigrations, E. ruidum practices stereotyped social carrying in the myrmicine mode. The discovery of this form of social carrying and of a recruitment pheromone in the Dufour's gland secretions support the hypothesis that the subfamily Myrmicinae is derived from an ectatommine ancestor. Other communication behaviors exhibited by E. ruidum include exchange of liquid food carried between the mandibles, chemical alarm communication, nest entrance marking, and an additional social carrying posture previously unknown in ants.
Familiarity Breeds Tolerance: the Development of Social Stability in Flocking Siskins (Carduelis spinus)
Authors: Senar J. C. , Camerino M. , Metcalfe N. B.
Published: May 2010

Behavioural integration associated with the fusion of two flocks is analyzed in captive siskins (Carduelis spinus) by quantifying changes in social behaviour with time since joining. In general there was an increase in the incidence of tolerant behaviour, supplanting attacks and hopping withdrawals with time since fusion of the flocks. However, the number of displays and flights showed the opposite, negative, trend. Taking dominance status into account, the greatest change in behaviour with time since joining is an increase in tolerance by dominants of new flock companions. Factorial analysis of correspondences was used to study how different birds changed their behaviour with time since joining a flock. This analysis showed that the introduction of new birds did not disrupt relationships with familiar birds, and that residents are dominant in interactions with the incoming new flock companions. The analysis also demonstrated that relationships within the new flock had stabilized 20 days after the flocks had joined. The characteristics of the socially integrated group of siskins are quite similar to those described by Rohwer & Ewald (1981) in their shepherds hypothesis: dominants tolerate their subordinates feeding in close proximity, offering them a profitable feeding area, but also supplant them to obtain food; both dominants and subordinates benefit from being in a flock. As a consequence, constant changes of membership in flocks is costly not only because birds lose dominance status, but also the advantages of clear dominant and subordinate roles.
Differences in Behavior and Social Organization of Female Guinea Pigs as a Function of the Presence of a Male
Authors: Thyen Yvonne , Hendrichs Hubert
Published: May 2010

Object of the study was the variability of social behavior and organization in female guinea pigs as a function of the presence of a male. Four groups of 8 females were observed. Two of these groups were without a male, the other two had a sexually experienced, sterilized male. All females were about 20 d old at the beginning of the study. In the groups without a male the females formed clear and stable dominance relationships resulting in a linear rank order. The frequency of agonistic behavior was higher compared to the other groups. Some of these females displayed male‐like courtship behavior. Among the females in the groups with a male only the alpha and omega positions were stable, while the dominance relations between the other females remained unstable. These females directed about 40–50 % of their contact behavior towards the male. In relation to the presence or absence of a male the females differed in their social orientation: those who lived with a male were strongly orientated towards it, those living without a male were strongly oriented towards each other. The hypothesis is put forward, that the females in the two situations differed in their motivational states. For the females living with a male this animal was a stable point of social reference, while for the females living without a male their stable dominance structure — with more agonistic behavior — was the most important stabilizing factor.
The Role of Eyespots in Predator Recognition and Antipredatory Behaviour of the Paradise Fish, Macropodus opercularis L.
Authors: Altbäcker Vilmos , Csányi Vilmos
Published: May 2010

The behaviour of the paradise fish in the presence of either a living pike or catfish or various dummies or a catfish equipped with a pair of artificial big eyes was studied. Analyzing the first encounter two separate periods of the predator recognition process could be identified. The primary form of the antipredatory reaction was orientation (looking at the object while keeping a constant eye and body position) which was elicited by any fish‐like bodies but not by bare eyes without a body. During orientation the presence of pike or catfish equipped with artificial eyes or a dummy with horizontal eyes elicited fin erecting display. This reaction was sporadic in the presence of a normal catfish which has very small eyes. The biological significance of this separate organization of exploration is discussed.
Effects of Exogenous Androgen and Antiandrogen on Territorial and Nonterritorial Red‐winged Blackbirds (Aves: Icterinae)
Authors: Beletsky Les D. , Orians Gordon H. , Wingfield John C.
Published: May 2010

We investigated the role of testosterone (T) in territory establishment and maintenance in male red‐winged blackbirds (Agelaius phoeniceus) by implanting exogenous T or pharmacological agents that block the action of T in nonterritorial floaters and territory owners. Floaters with artificially elevated plasma T levels were unable to obtain territories. Territory owners implanted with T did not expand their territories, although they engaged in more aggressive behavior than did control males. Flutamide, which binds to T receptors in target areas, had no effect on territoriality. However, most territory owners given a combination of flutamide and ATD, an aromatization blocker, lost portions of their territories even though they actively defended them. Our results 1) suggest that, although T influences aggressive behavior, elevated plasma levels alone are insufficient to overcome previously‐established social relationships between territory owners or between owners and floaters; 2) indicate that impairing the action of T leads to reduced abilities of territory owners to maintain territories against vigorous challenges: and 3) support recent findings that T acts on reproductive behavior in birds through both androgenic and estrogenic metabolites.
Behavioural Variation in Echolocation Pulses of the Northern Bat, Eptesicus nilssoni
Authors: Rydell Jens
Published: May 2010

17 northern bats, comprising a maternity colony, were observed and recorded in their natural feeding habitat in southern Sweden. They searched for insects in more or less open habitats, 2–50 m above ground, and usually established individual feeding territories, which were patrolled in straight or slightly curved flight paths at rather constant altitudes. Duration, bandwidth, amplitude, repetition rate and, to a lesser extent, terminal frequency of the echolocation pulses varied according to feeding habitat and situation. In general, long (13.0–17.7 ms), loud, shallow frequency‐modulated (FM) signals were used during search flight near treetop level (15 m) or above. At lower altitudes, steep FM‐components were added, and the terminal shallow‐sweep portions were shortened. These pulses were 6.3–13.4 ms long. Steep FM‐signals of short (0.4–8.4 ms) duration and relatively low amplitude were used in the vicinity of obstacles or targets.
Predicting Current Reproductive Success of Goose Pairs Anser indicus from Male and Female Reproductive History
Authors: Lamprecht Jürg
Published: May 2010

A multiple regression analysis of current reproductive success (goslings fledged) on three male and female life‐history traits (age, previous breeding periods, previous successes) was carried out for 31 semicaptive pairs of barheaded geese Anser indicus. Of the female variables, age proved positively and the number of previous nesting periods negatively related to current success. The latter relationship suggests that incubation has costs in terms of future fecundity for the female. Of the male variables, age was negatively and the number of previous fledging successes positively related to current reproductive success. Attempts with additional data to explain these findings in the male either by a positive feedback of success on future success or by differences in male quality gave inconclusive results, as did earlier attempts to demonstrate reproductive costs in geese and swans. In monogamous species with long‐term pair bonds, where male and female share most of their life history but specialize in different activities, reproduction may affect the sexes in different ways. If the correlations between life‐history traits of mates are not accounted for, individual strategies or constraints may be obscured by opposing effects in the mate.
Evaluating Hypotheses on the Evolution of Helping Behaviour in the Bell Miner (Manorina melanophrys)
Authors: Jamieson Ian , Craig John
Published: May 2010

In an analysis of the pattern of helping at the nest in bell miners (Manorina melanophrys), Clarke (1989) examined five hypotheses that could explain the evolution of helping behaviour in this species. We applaud the attempt by Clarke to consider many different hypotheses, but believe that more careful formulation of the hypotheses, more appropriate statistical analyses, and eventual experimental testing are required before his conclusions can be accepted.
Parental Care in Burying Beetles: The Organization of Male and Female Brood‐care Behavior
Authors: Fetherston Isabelle A. , Scott Michelle Pellissier , Traniello James F. A.
Published: May 2010

Parental care in the burying beetle Nicrophorus orbicollis was studied by comparing the composition of male and female repertories and time budgets and by analyzing the pairwise transition frequencies of brood‐care acts performed by each sex. Males and females performed the same brood‐care acts, but the frequency and duration of several acts differed significantly between the sexes. Males spent more time guarding the brood chamber than did females and females regurgitated to larvae more frequently than did males. Transition frequencies between behavior acts were used to attempt to define roles to examine the organization of behavior. There were no important significant associations between acts suggesting that behavior is not organized into roles but remains flexible. The data support the hypothesis that brood provisioning and brood guarding both were important in the evolution of paternal care in this species.
The American Alligator Detects Food Chemicals in Aquatic and Terrestrial Environments
Authors: Weldon Paul J. , Swenson Daryl J. , Olson John K. , Brinkmeier William G.
Published: May 2010

American alligators (Alligator mississippiensis) were offered raw meat or animal carcasses under water or on land in experiments where only chemoreception could be used to discriminate between these and control materials. Alligators also were presented with aqueous extracts and airborne chemicals from meat. Juvenile alligators, tested in indoor tanks, opened more cheesecloth packets containing meat than control packets when these materials were placed under water and on platforms above the water surface. Adult alligators, tested in outdoor semi‐natural enclosures, removed more cheesecloth‐wrapped meat presented under water, and more of both meat and raccoon (Procyon lotor) carcasses placed under perforated baskets on land, than control materials. Juvenile alligators, tested in tanks partially filled with water, exhibited more lateral head movements and mouth‐openings to an aqueous beef extract than to water alone. Juvenile alligators, tested in an olfactometer, exhibited more gular pumps to airborne chemicals from beef than to distilled water. These experiments indicate that alligators may use chemical cues to locate food both on land and under water, and that they detect both water‐ and airborne chemicals from meat.
Spatial Dispersion and Nonmigratory Spawning in the Bluehead Wrasse (Thalassoma bifasciatum)
Authors: Tecumseh W. , Fitch S. , Shapiro Douglas Y.
Published: May 2010

Earlier studies of the behavior of the bluehead wrasse Thalassoma bifasciatum have shown it to be a migratory spawner with large terminal‐phase males defending temporary spawning territories. We describe a variant social structure where fish occupy permanent home ranges, spawn within or near these home ranges, and are not territorial. Movements of identified terminal‐phase and intermediate males and females were mapped in the backreef areas of three coral reefs in Puerto Rico. Locations of spawns were then compared with these home‐range maps. All fish used most or all of their morning home range during the afternoon spawning period. Both terminal‐phase males and females spawned within or near their home ranges. Males were relatively tolerant of other males during the afternoon spawning period: only one in five encounters between large males resulted in aggressive chases. The location of chases bore no relation to spawning sites, areas of morning foraging, or to home‐range borders. A Monte Carlo computer simulation was used to measure home‐range dispersion of terminal‐phase and intermediate males at our main site. If males were territorial, we should expect their home ranges to be significantly overdispersed within the cumulative area they occupied. During the first year male home ranges were overdispersed but during the second year they were randomly dispersed, even though the same number of terminal‐phase males occupied the same study site both years. Differences in social behavior between backreef areas and other areas reported in the literature, and found in other portions of our reefs, may be related to differences in feeding ecology between populations and between different portions of the same reef.
Directional Sexual Selection Cannot Explain Variation in Song Repertoire Size in the New World Blackbirds (Icterinae)
Authors: Irwin Rebecca E.
Published: May 2010

Hypotheses that song repertoire evolves by way of directional sexual selection for large repertoires were examined with a comparative study of the avian subfamily Icterinae (Passeriformes: Emberiznae). Song repertoire size varies between closely related icterine species, so phylogenetic effects cannot explain repertoire size variation. Overall, song repertoire is not associated with polygyny or with presence or absence of territoriality.

Different associations of repertoire with mating system are observed in different icterine groups. Either the directional hypotheses do not apply to the evolution of song repertoire in the Icterinae, or different processes of directional sexual selection have occurred in different icterine groups.
Parent‐offspring Conflict during the Post‐fledging Period in the Egyptian Vulture Neophron percnopterus (Aves, Accipitridae)
Authors: Ceballos Olga , Donazar Jose A.
Published: May 2010

Egyptian vultures were studied during their post‐fledging dependence period in northern Spain in order to detect if there were parent‐offspring and sibling tensions during the transition of young to independence. The frequency of parental feedings and the frequency of movements of the parents towards their young decreased during the post‐fledging period, especially in its final part. At the same time, the frequency of movements and of aggression by the young towards their parents increased. Aggression by adults to their young was not observed. Siblings disputed feedings, but there was no other evidence for sibling conflict. The results suggest that parent‐offspring and sibling conflict exists and that its development is broken by the departure of young on migration. Some behavioural traits of adults (maintenance of distance from young and of intensity of nest‐defence, tolerance of young during foraging trips through the home range) do not accord with parent‐offspring conflict perhaps because they are related to factors other than family tension.
Aggression among Lekking Male Fallow Deer (Dama dama): Territory Effects and Relationship with Copulatory Success
Authors: Festa‐Bianchet Marco , Apollonio Marco , Mari Franco , Rasola Giulia
Published: May 2010

We studied the aggressive behavior of territorial male fallow deer (Dama dama) at two leks. Daily number of escalated fights was not correlated with number of matings. A dominance index including all agonistic interactions was weakly correlated with copulatory success; the correlation was stronger when each half of the rut was considered separately. Dominance likely changed over the rut due to fatigue. We ranked lek territories by the number of copulations seen in each. Males that won fights were likely to take over the loser's territory only if it ranked higher than the one they held. Winners were more likely to fight with a third male after defeating an opponent that held a higher‐ranking territory than one from a lower‐ranking territory. Exposure to attacks by third‐party males may be a major cost of fighting. Males appear aware of the relative value of different lek territories, but the frequency of aggression was not scaled to potential fitness benefits, possibly because males seldom fought with opponents they were unlikely to beat. The outcome of interactions on the lek may not always reflect the relative dominance rank of the contestants. Females are unlikely to use the outcome of fights as a direct criterion for mate selection.
Representation of Faces in Longtailed Macaques (Macaca fascicularis)
Authors: Dittrich Winand
Published: May 2010

The experiments described in this study were intended to increase our knowledge about social cognition in primates. Longtailed macaques (Macaca fascicularis) had to discriminate facial drawings of different emotional expressions. A new experimental approach was used. During the experimental sessions social interactions within the group were permitted, but the learning behaviour of individual monkeys was analysed. The procedure consisted of a simultaneous discrimination between four visual patterns under continuous reinforcement. It has implications not only for simple tasks of stimulus discrimination but also for complex problems of internal representations and visual communication.

The monkeys learned quickly to discriminate faces of different emotional expressions. This discrimination ability was completely invariant with variations of colour, brightness, size, and rotation. Rotated and inverted faces were recognized perfectly. A preference test for particular features resulted in a graded estimation of particular facial components. Most important for face recognition was the outline, followed by the eye region and the mouth. An asymmetry in recognition of the left and right halves of the face was found. Further tests involving jumbled faces indicated that not only the presence of distinct facial cues but the specific relation of facial features is essential in recognizing faces. The experiment generally confirms that causal mechanisms of social cognition in non‐human primates can be studied experimentally. The behavioural results are highly consistent with findings from neurophysiology and research with human subjects.
Structural Variation in the Call of the Cory's Shearwater (Calonectris diomedea, Aves, Procellariidae)
Authors: Bretagnolle Vincent , Lequette Benoit
Published: May 2010

The duet call, the principal vocalization of Cory's shearwaters, was structurally variable with different classes of call being apparent, corresponding to different individuals, sexes and populations. In playback tests, birds responded more frequently to the call of their mate than to other birds, birds of a given sex responded more frequently to playback calls of their own sex and birds of a given locality responded more frequently to birds of their own locality. We suggest some biological functions with respect to mating strategy, individual recognition, territorial behaviour, and population isolation.
Body Size Effects on the Acoustic Structure of Pigtail Macaque (Macaca nemestrina) Screams
Authors: Gouzoules Harold , Gouzoules Sarah
Published: May 2010

Scream vocalizations produced by pigtail macaques during agonistic encounters were classified according to caller body weight (small, medium, large) on the basis of six frequency‐related acoustic variables using direct discriminant analysis. Separate discriminant analyses were run for: 1. calls produced when the attack involved an opponent higher‐ranking than the victim and contact occurred, and 2. calls produced when the opponent was higher‐ranking, but no contact occurred. Screams were correctly classified as to the caller's weight class at levels significantly above those expected by chance alone. Screams given during contact aggression were classified significantly better than those given in the absence of contact. The effect of greater arousal level (fear) on the frequency range of calls may account for this difference. Macaque screams are representational signals that are important in the solicitation of agonistic aid from allies in the social group. That a relationship between body size and the frequency of screams is nonetheless evident argues for the fundamental nature of the relationship.
Strategies of Spatial Behaviour in Helix pomatia
Authors: Lind Hans
Published: May 2010

Seasonal and lifetime spatial movements were studied in the field in a large number of marked individuals. Most snails were resident, each within a small part of the suitable habitat. Three different types of spatial movement patterns could be recognized. Characteristic of most snails were radiating movements between permanent core areas in the wood and principal feeding areas in glades, and sometimes explorations. The duration of the excursions was usually between a week and a month. Two different return strategies seem to exist in Helix, one adapted to the utilization of known habitats within the home range, and one adapted to secure site fidelity. Explorations were usually shorter than the critical homing distance and thereby the risk of disorientation was reduced. Juveniles spent much time in feeding areas maximizing growth, whereas adults in midsummer spent much time in the wood thereby probably increasing the chance of survival for next year's reproduction and of exploring new feeding areas. It seems that a rather permanent home range develops from birth on through unlearned orientation responses, exploration, topographic learning and return movements. Some individuals in the study area were extremely stationary, others used an exploratory strategy and increased their home ranges with new feeding areas. The exploratory strategy of resident snails may be an investment which pays off if the suitability of the habitat decreases. There is some evidence that different feeding places are assessed and that a home range can be partially changed according to this. Snails in one habitat of decreasing quality showed a relatively high emigration frequency. They used one of two different strategies: Exploration and gradual home range displacement, or exploration and sudden emigration over a relatively long distance. Emigrants always settled in a good snail habitat, and habitat assessment is probably part of both strategies. Non‐strategic, “accidental” emigration also occurred. No evidence of age‐dependent dispersal was found. Relevant parts of the animal migration model presented by Baker (1978) are confirmed.
Ethotypic Variation of Prey Recognition in Juvenile Anolis lineatopus (Reptilia: Iguanidae)
Authors: von Brockhusen‐Holzer Friederike , Curio Eberhard
Published: May 2010

Among prey‐naive Anolis lineatopus from Jamaica, individuals reject ants most commonly, crickets less commonly, and waxmoth larvae almost never. This study investigates the individual differences in the mechanism underlying prey perception in two of many ethotypes found, i.e., cricket‐rejectors and cricket‐acceptors. In one experiment artificially coloured live waxmoth larvae, crickets and ants were presented, in another experiment crickets and waxmoth larvae were moved passively with different speeds. Ethotypes differ in their evaluation of the interaction of prey key stimuli. Cricket‐rejectors and cricket‐acceptors differ in their responses to both crickets and waxmoth larvae that were either unicoloured yellow or black, but not in their responses to two types of ants of either colouration. Both ethotypes also differ in their preferences for artificially moved crickets and waxmoth larvae as a function of the interaction of prey type and velocity.

In all but two prey items there is interaction in the perceptual pathways concerned. The first presentation in ontogeny of an ant inhibits attack on a cricket presented the next day. Some results suggest that ethotypes differ but gradually in their evaluation of stimuli presented, with cricket‐rejectors having a higher threshold for attack. However, other results suggest that cricket‐rejectors evaluate certain prey in a way qualitatively different from that of acceptors. At present there is little evidence for an understanding of the ethotypic differences of prey selection at a neural level, probably because neuroethologists have failed to look at individual differences of prey recognition; this failure is discussed in some detail.
Variations of Predatory Tactics of a Water Bug during Development
Authors: Cloarec Ann
Published: May 2010

At all developmental stages, Diplonychus indicus Venk. & Rao (Heteroptera: Belostomatidae) bugs make predatory attempts and catch prey both from ambush and while foraging actively. The distribution of predatory movements between these two foraging modes does not vary significantly during development, although a bug generally performs more predatory attempts from ambush than during active search. Both modes were subdivided and six different predatory movement types were recorded. These different predatory types are not all performed at the same frequency at all developmental stages. The proportion of predatory attempts including a preliminary lunge decreases with age whereas the proportion of simple predatory attempts (strike) increases with age. There is a significant effect of developmental stage and of predatory mode on capture success. General capture success rate increases with age and success rates vary with predatory type. Capture success of predatory attempts made while swimming is always lower than capture success of simple predatory attempts (strike). These rates do not vary during development. On the contrary, success rates for the predatory types dive and lunge increase with developmental stage. For some predatory categories, capture success varies with predator‐prey distance. The data then suggest that the bugs are undershooting.
Defining Natural Categories in Acoustic Signals: Comparison of Three Methods Applied to ‘Chick‐a‐dee’ Call Notes
Authors: Nowicki Stephen , Nelson Douglas A.
Published: May 2010

Identifying units of behavior is a universal problem in ethology. Here we compare three different techniques for identifying natural categories among notes in the chick‐a‐dee call of the black‐capped chickadee (Parus atricapillus). The combinatorial nature of ‘chick‐a‐dee’ calls, in which different note combinations are presumed to convey different messages, makes a problem of note classification especially relevant. The three techniques we used were (1) multidimensional scaling of inter‐note similarities derived from two‐dimensional cross‐correlation of digital spectrograms, 2) visual sorting of notes by human observers, and 3) k‐means cluster analysis based on a principal components analysis of 14 measured acoustic features. The three methods yielded generally concordant results, with closest agreement between the multidimensional scaling and visual classifications. We discuss possible mechanisms of information coding and perception, and the significance of these for the chick‐a‐dee call system. The techniques we employed provide powerful, complementary tools for the analysis of variation in acoustic communication signals.
A Quantitative Analysis of the Sounds of Hector's Dolphin
Authors: Dawson Stephen M. , Thorpe C. William
Published: May 2010

We developed an automatic, computer‐based system in which digital signal processing techniques were used to measure 31 variables from digitized Hector's dolphin (Cephalorhynchus hectori) sounds. Principal component analyses of these data were used to investigate the relationships between sounds. Hector's dolphins make only a very few types of pulsed “clicks”, most of which are centred around 125 kHz. None of these had an average frequency of less than 82 kHz, and the only audible sounds were made up of high‐frequency clicks repeated at such high rates that the repetition rate was audible to us as a tonal “cry” or “squeal”. In comparison to signal levels recorded from other cetaceans, all the Hector's dolphin signals were low‐level; the maximum received sound pressure level was 163 dB (re 1μPa).
Provisioning and Food Sharing by Lactating Spotted Hyenas, Crocuta crocuta (Mammalia: Hyaenidae)
Authors: Holekamp Kay E. , Smale Laura
Published: May 2010

In contrast to most other carnivores, spotted hyenas (Crocuta crocuta) do not regularly carry food back to their dens for provisioning of dependent young. Kruuk (1976) and Mills (1989) hypothesized that high levels of competition for provisioned food at the communal dens utilized by spotted hyenas may have selected against provisioning behavior in this species. We observed lactating female spotted hyenas carry food from ungulate kills to their dependent cubs at the den 18 times, and share food with their dependent cubs at kills 33 times. We used these data to test the Kruuk/Mills hypothesis by assessing effects of feeding competition on provisioning behavior. Provisioning rates were low, and were correlated with social rank. Provisioning attempts were often unsuccessful. Females dominant to the provisioner, with cubs also residing at the communal den, were the most effective competitors for provisioned food. Attempts to share food with cubs at kills were more successful than were attempts to provision cubs at the den. Our data thus support the Kruuk/Mills hypothesis.
Probing, Assessment, and Management during Interactions between Ground Squirrels and Rattlesnakes
Authors: Rowe Matthew P. , Owings Donald H.
Published: May 2010

The predator‐prey relationship between California ground squirrels (Spermophilus beecheyi) and northern Pacific rattlesnakes (Crotalus viridis) is a useful system for exploring conflict and assessment. Rattlesnakes are major predators of ground squirrel pups, but pose a less significant threat to adult squirrels. Adults approach, harass, and even attack rattlesnakes in defense of their pups.

Two factors that may influence risk to both squirrel and snake during encounters are the size and body temperature of the rattlesnake. We used high‐speed video to analyze the strikes of rattlesnakes of various sizes tested at different body temperatures. Results indicate that warmer snakes are more dangerous because they strike with higher velocity, greater accuracy, and less hesitation. Similarly, larger snakes are more dangerous because they can strike farther and at higher speeds, and keep their fangs embedded longer. Thus, ground squirrels would benefit from extracting information about a rattlesnake's size and temperature.

The converse of our results is that cooler, smaller rattlesnakes may be more vulnerable. These snakes could mitigate their risk by avoiding dangerous adversaries and minimizing cues that divulge their weaknesses. Such tactics might explain the active probing that squirrels direct at rattlesnakes, which may function to overcome a snake's resistance to disclosing its vulnerability.
Coupling Delayed Breeding with Short‐distance Dispersal in Cooperatively Breeding Birds
Authors: Zack Steve
Published: May 2010

Short‐distance dispersal in cooperatively breeding birds is demonstrated and a new model describes how it could be causally related to delayed breeding. Nonbreeders are hypothesized to wait for specific, adjacent territories of high quality. Strong, predictable differences in territory quality select for extended natal philopatry in comparison with species whose young disperse upon maturity. A nonbreeder's ability to discriminate territory quality, and competitive advantages of age and proximity in obtaining nearby breeding positions, are necessary conditions of this model. Direct benefits to both males (potential for inheritance of a breeding position on the natal territory) and females (priority to nearby territories of high quality) result from philopatry. This model differs from most others by emphasizing potential direct benefits of delayed dispersal, rather than assuming constraints, such as habitat saturation. Short‐distance dispersal is widespread in other bird and mammal social systems characterized by natal philopatry and delayed breeding, suggesting a general application of this model.
Quantitative Analysis of the Ontogeny of Play Behaviour in Canid Hybrids
Authors: Willkomm Silke
Published: May 2010

The question how far the ontogeny of social behaviour shows similarities and to what extent it is genetically determined is investigated for 3 F2 canid hybrids of one litter by the example of contact play behaviour. It is known that jackals, especially the golden jackal (Canis aureus L.) display a number of differences in social behaviour and a very early ontogeny compared with the wolf (C. lupus L.) and the domesticated dog (C. I. forma familiaris). In this study behaviours were classified by timing the duration of single events from video records. The analysis bases on the duration of special patterns of behaviour and not, as is usually done, on single observations. Readiness to play is of special importance. It is measured by the number of plays initiated and behaviour during play. Whereas individual duration of play of these 3 F2 hybrids is greatly influenced by exogene factors, the maximum readiness to play, occurring over a marked time interval, seems endogenously determined. The different inborn development of readiness to play leads to very different frequencies of partner combinations during the various phases of development. Animals with much play initiative more often take part in contact play of their own accord. This establishes the order of frequencies of the playmates chosen. The frequency of successfully triggering contact play and the duration of the individual play initiative turn out to be a suitable measure of the — otherwise hardly recordable — genetically determined readiness to play.