Showing papers in "Behaviour in 2002"

Tools and brains in birds

Abstract: Tools are traditionally defined as objects that are used as an extension of the body and held directly in the hand or mouth. By these standards, a vulture breaking an egg by hitting it with a stone uses a tool, but a gull dropping an egg on a rock does not. This distinction between true and borderline (or proto-tool) cases has been criticized for its arbitrariness and anthropocentrism. We show here that relative size of the neostriatum and whole brain distinguish the true and borderline categories in birds using tools to obtain food or water. From two sources, the specialized literature on tools and an innovation data base gathered in the short note sections of 68 journals in 7 areas of the world, we collected 39 true (e.g. use of probes, hammers, sponges, scoops) and 86 borderline (e.g. bait fishing, battering and dropping on anvils, holding with wedges and skewers) cases of tool use in 104 species from 15 parvorders. True tool users have a larger mean residual brain size (regressed against body weight) than do users of borderline tools, confirming the distinction in the literature. In multiple regressions, residual brain size and residual size of the neostriatum (one of the areas in the avian telencephalon thought to be equivalent to the mammalian neocortex) are the best predictors of true tool use reports per taxon. Innovation rate is the best predictor of borderline tool use distribution. Despite the strong concentration of true tool use cases in Corvida and Passerida, independent constrasts suggest that common ancestry is not responsible for the association between tool use and size of the neostriatum and whole brain. Our results demonstrate that birds are more frequent tool users than usually thought and that the complex cognitive processes involved in tool use may have repeatedly co-evolved with large brains in several orders of birds.

Ecological models of female social relationships in primates: similarities, disparities, and some directions for future clarity

Abstract: Several models have been proposed to explain the variation that exists in female social relationships among diurnal primate species. While there are similarities among them, notably in the ecological cause of agonistic relationships among females within groups, their differences are most useful in testing which of the models most accurately reflects the real world. These include the question of whether competition is an inevitable cost of living in groups and whether female philopatry is a consequence of the costs of dispersal or the benefits of forming coalitions with female kin. We discuss in detail these similarities and differences, and attempt to integrate the models' divergent views into some guidelines for use in testing between models that will lead to the next generation of models.

Reciprocity and interchange in the social relationships of wild male chimpanzees

Abstract: Social relationships in nonhuman primates result from investments that individuals make while pursuing fitness-maximizing strategies. These strategies sometimes include social exchange, either reciprocity (exchange of the same acts) or interchange (exchange of different acts). Individuals in many species may negotiate for services in biological markets, particularly grooming and agonistic support. They also may compete for access to valuable social partners. Abundant evidence for reciprocity in grooming and in support and for competition over partners exists, notably for females in some cercopithecines. However, evidence for interchange of grooming and support is scarcer, and apparent interchange may be a byproduct of correlations between grooming or support and some third variable (e.g. dominance rank). Chimpanzees have been prominent in discussions of social exchange, especially because male chimpanzees cooperate in many ways. Most analyses of interchange have used data on captive chimpanzees; these provide good evidence for reciprocity, but ambiguity with regard to interchange. Data on an unusually large chimpanzee community at Ngogo, Kibale National Park, Uganda, strongly support the argument that social exchange is prominent in social relationships among males. Males at Ngogo show reciprocity in grooming and support. They also interchange grooming given and support received, as well as grooming received and support given, independently of reciprocity in grooming and support and of correlations of support and grooming with dominance rank. However, most cooperation in contests with third parties took low risk forms (e.g. both participants outranked their opponent). In this, males at Ngogo resemble captive chimpanzees and female cercopithecines. Reciprocity and interchange in this context may be important in the maintenance of social bonds between males, and in attainment and maintenance of high dominance rank, but probably represent mutualism, not reciprocal altruism.

Friendship among adult female blue monkeys (cercopithecus mitis)

Abstract: A study group of blue monkeys in the Kakamega Forest, Kenya, provides data on friendly relationships between adult females. Females are invariably antagonistic toward members of other groups, and collaborate with their own groupmates in defending territorial boundaries. Females are primarily responsible for these aggressive intergroup encounters, which occur every other day on average. Encounters are often immediately followed by intense grooming among adult females, which gives the impression of reinforcing the collaborative team. In some lower-density populations, intergroup aggression is rare; in these populations, and at Kakamega as well, female groupmates may provide other or additional services, such as protection against predators or aggressive males. Friendships among females of a single group are differentiated. Individuals interact with certain grooming and proximity partners much more than others. Despite low rates of agonism, blue monkey females also show stable if shallow dominance relationships, and linear hierarchies. Rank is not correlated with diet, feeding behavior or reproductive rate. Coalition formation is rare, and these females do not groom up the hierarchy. Grooming may simply be traded for itself, leading to highly symmetrical grooming bouts. Blue monkeys have been misclassified in theoretical papers on socioecology. Their behavior seems not to fit these models well, because certain features of their social system, related to within-group contest competition, do not co-occur as expected. Their hierarchical dominance relationships are also surprising, because rank seems to be uncorrelated with fitness-related variables. Finally, the rarity of affiliative behavior exhibited by these monkeys suggests that new ways of measuring friendships may be appropriate. The possible importance of, and reasons for, rare within-group coalitions are discussed.

Aggression to dummy cuckoos by potential European cuckoo hosts

Abstract: Aggression directed by 53 potential host species towards a dummy of the parasitic common cuckoo, Cuculus canorus, was tested in relation to their breeding habitat, their suitability as a host and whether they were breeding in sympatry or not with the cuckoo. Host habitats were divided into three categories: (1) always breeding near trees, (2) some populations breeding near trees, others in open areas, and (3) always breeding in open areas. Each species was also placed in one of five categories according to their suitability as a cuckoo host. Strong support was found for predictions derived from the 'spatial habitat structure hypothesis', which argues that common cuckoos only breed in areas where they have access to vantage points in trees. Thus, species which have some populations breeding near trees and others breeding further from trees have a different cuckoo-host population dynamics than species that always breed near trees, or always breed in open areas. Aggression levels were highest among species regarded as being always suitable as hosts, and species which always breed near trees. However, populations breeding in sympatry with the cuckoo were more aggressive than allopatric populations, indicating the plasticity of aggressive behaviour. Adaptive behaviour in cuckoo hosts can be predicted from the 'spatial habitat structure hypothesis'.

Single and multichannel signal composition: facial expressions and vocalizations of rhesus macaques (macaca mulatta)

Abstract: A method for simultaneously examining visual and vocal components of expressive behavior is described, compiled from video recordings of social behavior of a free-ranging group of rhesus macaques on Cayo Santiago, Puerto Rico. I developed a catalog of expressive movements, and chronicled detailed information on visual and vocal components of 1215 individual behaviors. Two thirds of the events recorded were silent, supporting the idea that visual behaviors are primary for short distance communication in these macaques. Clusters of expressive components detected by Principal Component Analysis and Multiple Correspondence Analyses corresponded to threatening, submissive, and affiliative behaviors described previously, providing quantitative support both for these previous descriptions and for the suggestion that these three poles of behavior are important in daily social interaction. Silent expressions involved a greater variety of mouth positions than did vocalizations, which were produced with stereotyped mouth shapes. Other components of the face, not involved with articulation, were nonetheless associated with particular vocalizations: specific associations were found among barks, ears retracted, and head lowered on the one hand, and pant-threats, ears forward, and head raised on the other. Screams and squeaks were highly stereotyped, combined with prototypical grimace mouth positions, crouching and retreating. Girney vocalizations were accompanied by lipsmacking. Grunts were unaccompanied by other expressive components, evoking the suggestion that they may be predominantly neutral in valence.

Playbacks of loud calls to wild thomas langurs (primates; presbytis thomasi): the effect of familiarity

Abstract: Animals may behave aggressively towards neighbours. For several bird species it has been shown that males react more vigorously towards calls of neighbours from the centre of their home range than from the edge. This is usually explained by assuming that the centre of a home range is of higher value to a male than the edge. To test these ideas for a primate species, we conducted experiments with playbacks of loud calls on wild male and female Thomas langurs (Presbytis thomasi). These animals may defend resources in their range or protect their offspring from infanticide and males may defend their females. In natural situations between-group encounters in the centre of a home range by the intruding neighbour are more often accompanied by infanticidal attempts than encounters at the edge. Loud calls of neighbours played back from the centre of the home range caused a more vigorous reaction from the resident male than calls from the edge. However, males in food-containing trees did not respond differently to edge playbacks from males in non-food-containing trees. Although males seem to defend resources and not mates, male behaviour may be best explained by defence of infants against infanticide. Female behaviour is best explained by resource defence.

Relationship assessment through emotional mediation

Abstract: Social relationship is a concept that links the observable social interactions between group members to the inferred group social system. Social relationships allow animals (as well as the human observers) to predict the actions and responses of their partners and therefore guide their own. Social relationships can also be described as investments that benefit the individuals involved in them. Some benefits simply require stable association and some level of mutual tolerance, whereas others depend on the establishment of more fully developed social relationships. The variation in the quality of social relationships leads to a great flexibility in the frequency and quality of interaction with various group members and with the same individual over time. A key issue is therefore to understand the proximate mechanisms underlying such flexibility since individuals need to be able to assess relationship quality in order to maximise the benefits that social relationships provide. Assessment of social relationships should be based on the information contained in the various interactions that the partners exchange. Assessment should therefore require bookkeeping of the various interactions, computation of their relative frequencies, and conversion of their quality and information associated with them into common currencies. We propose emotional mediation as a possible mechanism that fulfils such requirements and provides the individual with a timely assessment to guide its social decision. Emotions are viewed as intervening variables that result from the integration of the information contained in the various interactions between two partners. Before presenting evidence for relationship assessment through emotional mediation, we define the concept of emotion in animals and provide evidence for measuring relevant emotions in non-human primates. Then, we present four examples obtained by combining findings from multiple studies. The examples provide evidence for emotion resulting from information contained in the interactions exchanged by the partners and for emotional differences being at the basis of the variation in social interactions. Thus, animals may appreciate variation in their social relationships through emotional mediation. This is a promising avenue to disclose the proximate mechanisms of relationship assessment and we suggest new lines of research to gather further evidence for the role of emotional mediation.

The effects of dominance on social foraging tactic use in house sparrows

Abstract: We investigated whether social foraging tactic use (producing and scrounging) in birds is affected by the dominance rank of individuals as predicted by a phenotype limited producer-scrounger game. In a captive flock of house sparrows, we observed the behaviour of the birds when they were foraging on a grid containing clumps of seeds. We measured the fighting success of the birds, determined the method by which they found food clumps (finding or joining), and measured their feeding rate. Joining were frequently observed and usually involved aggressive interactions. Most birds used both finding and joining to obtain food. We found that foraging method was related to dominance: the frequency of joining gradually increased with increasing dominance rank, as predicted by the phenotype limited model for flocks where there are moderate competitive asymmetries among the birds. Food intake rate of individuals was not related to either their dominance rank or foraging method. Similar weak relationships were predicted by the model among these variables for flocks with moderate competitive asymmetries. Behavioural variability among sparrows in locomotion frequency and vigilance was not related to their foraging method, but the rate of investigating potential food caches strongly decreased with increasing frequency of joining. We conclude that the phenotype limited model successfully predicts the relationship between dominance and joining frequency in house sparrows feeding on concentrated food sources, and we suggest that the distribution of food used in tests of the model may crucially affect their results.

Constraints on relationship formation among female primates

Abstract: The notion that female primates' relationships are adaptive is an explicit assumption of socioecological models of primate sociality. Here, we point out that there are other, implicit, assumptions about female relationships that also need to be considered when investigating the ultimate value of social relationships. First, there is the assumption that the operational definition of 'relationship' used in primate studies is an accurate reflection of the way in which monkeys themselves view their interactions with their peers. We also note that a relationship-based approach encourages a focus on the outcomes of social processes, rather than their dynamics, and could generate a potentially misleading view of primate sociality. Related to this first point, we also question the assumption that females possess the cognitive capacities required to engage in the long-term strategic decision-making and are capable of a high degree of forward planning. We argue that, at least among monkeys, this is unlikely to be the case, and any long-term 'planning' is the product of an evolved 'rule of thumb' and not real-time cognitive processing. Finally, we highlight the fact that group life is inherently dynamic and that chance demographic effects can limit females' social options to a degree that suggests short-term contingent decision-making would be the more optimal strategy for females to adopt. We suggest that greater understanding of these three elements is required for a true understanding of the adaptive nature of female relationships.

Learned recognition of heterospecific alarm cues enhances survival during encounters with predators

Abstract: Numerous species of aquatic animals release chemical cues when attacked by a predator. These chemicals serve to warn other conspecifics, and in some cases heterospecifics, of danger, and hence have been termed alarm cues. Responses of animals to alarm cues produced by other species often need to be learned, yet mechanisms of learned recognition of heterospecific cues are not well understood. In this study, we tested whether fathead minnows (Pimephales promelas) could learn to recognize a heterospecific alarm cue when it was combined with conspecific alarm cue in the diet of a predator. We exposed fathead minnows to chemical stimuli collected from rainbow trout, Oncorhynchus mykiss, fed a mixed diet of minnows and brook stickleback, Culaea inconstans, or trout fed a mixed diet of swordtails, Xiphophorous helleri, and stickleback. To test if the minnows had acquired recognition of the heterospecific alarm cues, we exposed them to stickleback alarm cues and introduced an unknown predator, yellow perch (Perca flavescens) or northern pike (Esox lucius). Both perch and pike took longer to initiate an attack on minnows that were previously exposed to trout fed minnows and stickleback than those previously exposed to trout fed swordtails and stickleback. These results demonstrate that minnows can learn to recognize heterospecific alarm cues based on detecting the heterospecific cue in combination with minnow alarm cues in the diet of the predator. Ours is the first study to demonstrate that behavioural responses to heterospecific chemical alarm cues decreases the probability that the prey will be attacked and captured during an encounter with a predator.

The effect of the sex of an audience on male-male displays of siamese fighting fish (betta splendens)

Abstract: Communication in the natural environment often involves more than a simple sender-receiver dyad because signals may be detected by more than one individual (i.e. communication occurs in networks). The presence of individuals other than those involved in the signalling interaction has been shown to change signallers' behaviour. Previous experiments have shown that intra-sexual communication of male fighting fish (Betta splendens) is affected by the presence of a female but not by a male conspecific. However the experimental design did not allow the effect of the sex of the audience to be compared. We used an experimental design that allowed direct investigation of the effect of the sex of an audience on male-male fighting fish interactions. Our results show that the sex of a conspecific audience influences male-male aggressive displays. When a male audience was present subjects attempted significantly more bites and spent less time near the opponent than with a female audience. The results of this experiment support the view that the presence and sex of an audience is important in determining how individuals should display during an interaction.

Social dynamics of male muriquis (Brachyteles arachnoides hypoxanthus)

Abstract: We investigated patterns of sociality among wild male northern muriquis (Brachyteles arachnoides hypoxanthus) to explore some of the possible ways in which within-group scramble competition might shape their social and mating strategies. The 13 adult males in our study group spent an average of 54.5′4.2% of their time in proximity to at least one other adult male. They were more likely to associate with one another, but not with adult females, when they were resting than when they were feeding. Embrace rates were positively related to the proportion of time males spent in proximity during resting. Males that associated closely with one another tended to interact more often, although individual differences in male social styles and rates of interactions were apparent. Young adult males had significantly higher social maintenance rates than the oldest males in our sample, but no other effects of age were detected in any of our other behavioral comparisons. In roughly 20% of all dyads, one male valued the association significantly more than the other. Males tended to value associates with higher mating success than themselves, and to share access to the same females on the same days with their closest associates. Neither of the two pairs of maternal brothers in our study group were important associates to their kin, but brothers shared copulations in the same polyadic copulation partnerships with one another. Although still preliminary, our findings suggest that muriqui males differentiate among their possible social partners in ways that may minimize the variance in their mating success under the unusual conditions imposed by scramble competition for reproductive opportunities.

Affiliation and aggression among adult female rhesus macaques: a genetic analysis of paternal cohorts

Abstract: Kin selection promotes the evolution of social behaviour that increases the survival and reproductive success of close relatives. One prerequisite for kin selection is that individuals have the ability to discriminate between kin and nonkin. Studies incorporating data on paternal kinship are still rare, but in species with a high male reproductive skew, many adult females will be paternal half siblings. Using both microsatellites and DNA-fingerprinting, we here analyse data on paternal relatedness in order to compare the influence of maternal and paternal kinship on rates of affiliative and aggressive interactions among semi free-ranging adult female rhesus macaques (Macaca mulatta). Because paternal half siblings tend to be peers whereas maternal half siblings are almost always nonpeers, we also examine the interactions between age proximity and genetic relatedness on social behaviour. Genetic analyses show that male reproductive success is strongly skewed with 75% of infants within the troop having a paternal half sibling in the same age cohort. The highest rates of both affiliation and aggression occur among maternal half sisters. Adult females are significantly more affiliative, but not more aggressive, with paternal half sisters than with nonkin. Affiliative relationships declined in conjunction with increasing age difference among paternal half sisters, but the reverse effect was found for affiliative relationships among maternal half siblings. No association emerged among nonkin. Among both maternal and paternal kin, rates of affiliative and aggressive interactions increase as the degree of relatedness increased, thereby questioning the concept of a relatedness threshold as a mediator of social interactions in rhesus macaques. The asymmetry in affiliation and aggression between maternal and paternal half siblings, and the effect of age proximity on partitioning social interactions suggests that context-dependent kin discrimination characterises rhesus macaques. Paternal kin discrimination probably results from an interaction between phenotype matching and familiarity, rather than from one process or the other.

The stress response of european stonechats depends on the type of stressor

Abstract: The acute increase in plasma levels of corticosteroid hormones in response to a stressful situation is essential for adequate physiological and behavioural responses to unpredictable events. The pattern and amplitude of the corticosteroid stress response has been extensively studied to compare endocrine adaptations between different life history stages, but also to determine environmental and physiological disturbances. Most studies on birds have used a simple and repeatable standardized stress-protocol. After capture, blood samples are taken at fixed time intervals from the bird kept in a cloth bag. Capture and handling during this procedure are stressful events which typically result in enhanced secretion of corticosterone. However, it is not known whether the stress response obtained with the cloth bag protocol is comparable with a life-threatening situation such as the confrontation with a predator. In this study, we investigated the plasticity of the stress-response towards different stimuli. We compared the stress responses of European stonechats (Saxicola torquata rubicola) exposed to different stressors: (1) a standard cloth bag; (2) space restraint by caging; and (3) caging and additional confrontation with a live predator, a tawny owl (Strix aluco). Our results show that the stress response induced by the predator was greater and the stress response induced by the cage tended to be greater than that induced by the cloth bag protocol. Thus, the present study showed that the stress response may vary depending on the type of stressor.

Red jungle fowl have more contrafreeloading than white leghorn layers: effect of food deprivation and consequences for information gain

Abstract: Contrafreeloading (CFL), ie choosing food which requires work over free food, occurs at a higher rate in red jungle fowl ( Gallus gallus ) compared to White Leghorn layers We examined whether this difference between breeds was altered by food deprivation and whether it affected the information gained about alternative food sources In a first experiment, twenty birds of each breed were deprived for zero, three and six hours and then allowed a choice of feeding from freely available food or food mixed with wood shavings In both breeds, CFL tended to decrease after deprivation, but jungle fowl consistently showed more CFL than Leghorns also after food deprivation This shows that differences in CFL between breeds were not altered by food deprivation, and the larger CFL in jungle fowl may represent a genetically based difference in feeding strategy In a second experiment, we examined whether the differences in CFL affected how the birds acquired information about alternative food sites of different quality Twenty birds of each breed were allowed to forage during three 10 min sessions in a four armed maze, where symbols in each end of the arms indicated the location of four different quality food sources; 'high gain' (freely available food), 'medium gain' (70% food, 30% wood shavings), 'low gain' (30% food), and 'no gain' (100% wood shavings) Each bird was then tested in the same maze when the 'high gain' food source and its symbol had been removed, and the other three sources contained only the symbols and wood shavings Jungle fowl chose the symbol indicating the best available food source significantly more often than the Leghorns The results indicate that Leghorn gain less information during foraging, which may have consequences for their adaptation capacity in a production environment This could either be a consequence of Leghorns showing less CFL, or a generally impaired learning capacity of Leghorns compared to jungle fowl

The ontogeny of manual skill in wild chimpanzees: evidence from feeding on the fruit of saba florida

Abstract: When chimpanzees eat Saba florida fruit, the necessary processing requires extraction from within an inedible matrix, involving considerable manual dexterity at several stages, and typically elicits strong manual laterality: all these features suggest that it is a complex task for chimpanzees. Focal observations were made on 14 mother-infant pairs. Although infants gained fruit pulp and fruit parts from the mother, and reduced the need for bimanual coordination by feeding on still-attached fruit, they nevertheless used more varied procedures than adults to extract pulp. In contrast, adults often detached and transported several fruits at once, and used bimanual methods to open fruits. By 2 years old, infants were able to process whole fruits, but it was not until 4 years that they gained mastery of the full adult technique. Many of these changes can be understood in terms of maturation of manual abilities, including precision gripping, bimanual role differentiation and digit role differentiation. Social influences are also present, including synchronous feeding, close attention to the mother, and food-solicitation and sharing. We argue that adaptations for optimization of nutrition have the incidental consequence of scaffolding the learning process for the infant.

An expanded test of the ecological model of primate social evolution: competitive regimes and female bonding in three species of squirrel monkeys (saimiri oerstedii, s. boliviensis, and s. sciureus)

Abstract: Two critical premises underlie prevalent interpretations of the ecological basis of variation among female primate social behavior. The first is that food distribution affects competitive regimes for food experienced by females. This leads, in turn, to the second premise that these competitive regimes generate predictable patterns of female social relationships and residence. Long-term field studies of S. oerstedii at Corcovado, Costa Rica and S. boliviensis at Manu, Peru (Mitchell et al. , 1991) provide what is widely considered as the most powerful support to date for such an ecological model. The data from these two squirrel monkey field studies are entirely consistent with the various incarnations of the van Schaik (1989) and associates' models linking a cascade of predictions on within- and between-sex social bonds and dispersal patterns to the presence or absence of significant within-group contest competition for food. A key premise of these models is that females tolerate the significant costs of within-group food competition because of the advantages group living affords in reduction of predation risk.In the current study, comparable ecological and behavioral data from long-term field observations of known individuals of S. sciureus at Raleighvallen, Suriname are used to expand the test of ecological models to three species. In all three sites female within-group direct competition regimes clearly follow from the distribution of fruit patches. In Suriname, however, S. sciureus females exhibit weak social bonds and rarely form coalitions with other females despite frequent, intense, even vicious within-group direct food competition. Although all males appear to emigrate from their natal troops, some females do as well, probably exceeding about 10% of the female group membership annually. Yet the lack of consistency with the expectations of the ecological model is only superficial. In fact, S. sciureus is the exception that corroborates the general robustness of predictions made in the ecological model. The fruit patches defended by S. sciureus, although small, are usually dense, extremely rewarding and easily defended by the individual with the greatest resource holding potential. Female coalitions to defend fruit patches would not be stable, as one female can ultimately prevail in monopolizing the resource. The lack of reliable foraging benefits to females who form coalitions and the consequent lack of strong female social bonds among female S. sciureus are completely concordant with the logical rationale underlying the ecological model.

How adaptive or phylogenetically inert is primate social behaviour? a test with two sympatric colobines

Abstract: [Socio-ecological theories predict that females adapt their social behaviour to their environment On the other hand, as a result of phylogenetic inertia, social behaviour may be slow to catch up when the environment changes If social behaviour is adapted to the environment, competition and co-operation among females is predicted to reflect the characteristics of food sources Contest competition both between and within groups is expected to result in alliances among related, philopatric, females We compared social relationships and food characteristics of two sympatric and congeneric primate species, the red colobus and the black-and-white colobus of the Tai National Park, Ivory Coast We found that affiliative interactions among females were comparable between the species The differences in food characteristics could explain why black-and-white females competed more often than did red colobus females, both at the intra- and inter-group level In contrast to socio-ecological theory, female inter-group aggression was not linked to female philopatry in black-and-white colobus The species differed from each other and from other populations of the same or closely related species with respect to their inter-group behaviour which indicates that phylogenetic inertia did not constrain this aspect of social behaviour, Socio-ecological theories predict that females adapt their social behaviour to their environment On the other hand, as a result of phylogenetic inertia, social behaviour may be slow to catch up when the environment changes If social behaviour is adapted to the environment, competition and co-operation among females is predicted to reflect the characteristics of food sources Contest competition both between and within groups is expected to result in alliances among related, philopatric, females We compared social relationships and food characteristics of two sympatric and congeneric primate species, the red colobus and the black-and-white colobus of the Tai National Park, Ivory Coast We found that affiliative interactions among females were comparable between the species The differences in food characteristics could explain why black-and-white females competed more often than did red colobus females, both at the intra- and inter-group level In contrast to socio-ecological theory, female inter-group aggression was not linked to female philopatry in black-and-white colobus The species differed from each other and from other populations of the same or closely related species with respect to their inter-group behaviour which indicates that phylogenetic inertia did not constrain this aspect of social behaviour]

Sequential foraging behaviour of bottlenose dolphins, tursiops truncatus, in sarasota bay, fl

Abstract: Detailed analyses of dolphin foraging behaviour have typically been difficult due to researchers' inability to observe entire foraging sequences. Using a new observational tool I was able to observe sequences of behaviours leading to successful prey captures, including behaviours not previously described in Sarasota Bay dolphins. I defined a set of specific foraging behaviours and demonstrated their position in successful sequences by analyzing the conditional probability of their occurrence based the occurrence of a capture. The sequences of behaviours dolphins used were not deterministic, and individual dolphins displayed different behavioural repertoires. Foraging behaviours occurred at rates of up to 0.5 per minute during general activity categories commonly used in odontocete research, and the current results could assist in the interpretation of these activities.

Acoustical mother-offspring recognition in pigs (sus scrofa domestica)

Abstract: Parental recognition of offspring is important in highly social animals. Both wild and free-ranging domestic sows live in groups during lactation, except for a few days of isolation directly after parturition. It is therefore important that a sow is able to discriminate her own piglets from alien piglets both at close contact and from a distance. We investigated whether piglets' vocalizations at 10 days of age may serve this function. Vocalizations of own and alien piglets were recorded on day 9 post partum whilst the piglets were isolated from the sow for 5 min (isolation calls, i-calls) and when piglets were returned to their sows afterwards (contact calls, c-calls). We first examined whether the two types of piglet vocalizations include cues which make it possible to discriminate between individual litters. A total of 2155 i-calls and 475 c-calls were sampled. From digitized calls, a total of 50 acoustic parameters were calculated and then subjected to a discriminant function analysis (forward stepwise method). Both i-calls and c-calls could be classified significantly better to the correct litters than would be expected by chance. In a playback experiment, whether sows isolated from their piglets respond more strongly to i-calls and c-calls of their own piglets than to alien calls was tested. For both the i-calls (N = 12 sows) and c-calls (N = 8 sows) sows responded with more vocalizations to the playback of own piglets' voices than to the playback of alien piglets' voices. The study shows that piglet calls contain acoustic cues that are litter typical and that sows are able to recognize their offspring based on these cues.

Adaptations by great reed warblers to brood parasitism: a comparison of populations in sympatry and allopatry with the common cuckoo

Abstract: Egg rejection behaviour, as an antiparasite defence against brood parasitism was compared in two great reed warbler Acrocephalus arundinaceus populations In central Hungary the host population lives in sympatry with the common cuckoo Cuculus canorus, and it is heavily parasitised (ca 66%) In central Greece the great reed warbler occurs in allopatry with the cuckoo, so it is not parasitised at all Experimental parasitism with poorly mimetic (often called 'non-mimetic') artificial cuckoo eggs revealed a 100% rejection rate towards the foreign eggs in the Greek population, but the Hungarian hosts accepted 294% and rejected 706% of the model cuckoo eggs No other rejection type than ejection was observed The significantly higher level of rejection in Greece than in Hungary suggests that the Greek great reed warbler population is an abandoned host population of the cuckoo, which kept its egg recognition ability A computer-based image analysis of host's clutches revealed that interclutch variation in egg colour was greater than intraclutch variation in the Hungarian population, but not in the Greek population Spottedness of eggs were similar in both populations Generally, a tendency for a higher interclutch variation was found in Hungary Intraclutch variation was more similar in the two populations, but for the colour variables it showed a lower value in Hungary than in Greece The heavy cuckoo parasitism in Hungary is suggested to be the main cause for the increased interclutch variation in relation to intraclutch variation in egg appearance among great reed warbler clutches The high interclutch variation reduces the chance that the parasite egg's appearance matches that of the hosts', which facilitates hosts' egg discrimination

Behavioural responses to conspecific disturbance chemicals enhance survival of juvenile brook charr, salvelinus fontinalis, during encounters with predators

Abstract: Several species of aquatic organisms release chemical cues upon detecting predators. These chemicals may serve to 'warn' nearby conspecifics of the predator and hence have been termed disturbance cues. Disturbance cues are thought to be low-level indicators of risk to which prey animals respond with antipredator behaviour. However, little is known about the distribution of disturbance cues among different taxa or how prey animals use these cues to mediate their risk of predation. In this study we exposed brook charr (Salvelinus fontinalis) to water from a tank containing cues of disturbed or undisturbed conspecifics at the same time as we exposed them to cues of an unknown predator, northern pike (Esox lucius). In subsequent trials, we staged encounters between the charr and a pike and tested for differences in survival. We found that charr that were exposed to simultaneous cues from disturbed conspecifics and pike odour subsequently avoided the pike significantly more than charr that had been previously exposed to chemical stimuli from undisturbed charr plus pike odour. Moreover, pike took significantly longer to capture charr that had been previously exposed to disturbance cues from conspecifics plus pike stimuli compared to charr previously exposed to cues from undisturbed charr plus pike stimuli. Ours is the first study to demonstrate that detection of disturbance cues can provide a survival benefit during an encounter with a predator.

Costs associated with recognition and rejection of parasitic eggs in two European passerines

Abstract: Many avian brood parasite hosts accept parasitic eggs even though successful parasitism frequently is detrimental to their own reproduction. Such behaviour seems suboptimal, but has been explained by the existence of opposing selective pressures operating against the evolution of appropriate host defence. Costs associated with rejection and recognition of eggs are central topics in this respect. Here, we report the occurrence of such costs in two European passerines (chaffinches and blackcaps) that are good rejecters of foreign eggs, even though the common cuckoo does not presently use them as hosts. Since high rejection rates are maintained in the absence of parasitism, we predicted that few recognition errors are made by these species. We tested this prediction by monitoring the occurrence of such errors in both experimentally parasitised and non-parasitised host clutches. We found support for the prediction, as our results show that recognition errors are at best rare events in these two species. We discuss the role of intraspecific brood parasitism as well as other explanations for the retention of a high rejection rate in these species. Various studies have reported mixed support for the occurrence of recognition errors among cuckoo hosts, and we consider other explanations for the existence of both acceptors and rejecters of foreign eggs in host populations.

The vocal behaviour of male european treefrogs (hyla arborea): implications for inter- and intrasexual selection

Abstract: [Calls and calling behaviour were studied over two years in a population of individually marked European treefrogs ( Hyla arborea ), a hylid frog with a prolonged breeding season and a lek mating system. A mean daily air temperature of 4.5°C and a nightly water temperature of 9°C were found to represent lower thresholds for nightly calling activity. Large choruses started calling earlier and showed a longer nightly duration of calling activity than small choruses. Temporal properties of advertisement calls were determined mainly by water temperature, which explained up to 88% of the observed variation. Dominant frequency was determined mainly by male body weight, which explained 20% of the observed variance. Within-bout call rate, call duration, pulse period, number of pulses per call and dominant frequency showed little within-male variability, but overall call activity and the number of calls per call bout varied considerably between different recordings of the same individual males. Statistically significant differences between different males were found for withinbout call rate, call duration, number of calls per call bout, number of pulses per call, and dominant frequency. Observed patterns of variability in call properties are discussed in the context of possible implications for female mate choice and male-male recognition., Calls and calling behaviour were studied over two years in a population of individually marked European treefrogs ( Hyla arborea ), a hylid frog with a prolonged breeding season and a lek mating system. A mean daily air temperature of 4.5°C and a nightly water temperature of 9°C were found to represent lower thresholds for nightly calling activity. Large choruses started calling earlier and showed a longer nightly duration of calling activity than small choruses. Temporal properties of advertisement calls were determined mainly by water temperature, which explained up to 88% of the observed variation. Dominant frequency was determined mainly by male body weight, which explained 20% of the observed variance. Within-bout call rate, call duration, pulse period, number of pulses per call and dominant frequency showed little within-male variability, but overall call activity and the number of calls per call bout varied considerably between different recordings of the same individual males. Statistically significant differences between different males were found for withinbout call rate, call duration, number of calls per call bout, number of pulses per call, and dominant frequency. Observed patterns of variability in call properties are discussed in the context of possible implications for female mate choice and male-male recognition.]

Individual differences in behaviour: a test of 'coping style' does not predict resident-intruder aggressiveness in pigs

Abstract: Temperament traits in animals are those which are stable across time and predictive of behaviour in other situations. Individuals can be identified as showing either active (pro-active) or passive (re-active) responses to a variety of challenges, and these are often referred to as 'coping styles'. Although most studied in rodents, coping styles are found in a variety of vertebrate species. In rodents, the resident-intruder aggressiveness test is a key measure of coping style, whereas in pigs, several recent studies have used a 'backtest' as the key measure of coping: A piglet is held on its back for one minute and the frequency of struggling bouts ('escape attempts') is recorded. In this study, we compared pig behaviour in backtests performed on 3 and 9 days of age, with aggressiveness was measured using 2 resident-intruder tests between 16 and 19 days post-weaning. A smaller unfamiliar intruder was introduced into part of the resident pig's home pen, and resident attack latency was recorded. Struggling bout frequency in the backtests showed a unimodal distribution. Data were analysed both as a continuous distribution and by comparing only the piglets from either extreme of the distribution (for comparison with other studies, top and bottom 25%). There was good repeatability of outcome (struggling frequency) over the two backtests, and over the two resident-intruder tests (attack latency and occurrence of resident attacks). However, no relationship was found between behaviour in the backtests and aggression in the resident-intruder tests, despite exhaustive analysis. Other authors have found that pigs show consistent responses to challenges, suggesting a degree of stable temperament. In line with the present findings though, most found no correlation between social and non-social responses. Other published experiments show that in pigs, the backtest can predict several physiological differences characteristic of coping styles. However, the present study shows that in pigs, aggressiveness and struggling in a backtest are not correlated, suggesting that they do not represent different expressions of the same underlying 'coping' trait.

Playbacks of loud calls to wild thomas langurs (primates; presbytis thomasi): the effect of familiarity

Abstract: Animals may behave aggressively towards neighbours. For several bird species it has been shown that males react more vigorously towards calls of neighbours from the centre of their home range than from the edge. This is usually explained by assuming that the centre of a home range is of higher value to a male than the edge. To test these ideas for a primate species, we conducted experiments with playbacks of loud calls on wild male and female Thomas langurs (Presbytis thomasi). These animals may defend resources in their range or protect their offspring from infanticide and males may defend their females. In natural situations between-group encounters in the centre of a home range by the intruding neighbour are more often accompanied by infanticidal attempts than encounters at the edge. Loud calls of neighbours played back from the centre of the home range caused a more vigorous reaction from the resident male than calls from the edge. However, males in food-containing trees did not respond differently to edge playbacks from males in non-food-containing trees. Although males seem to defend resources and not mates, male behaviour may be best explained by defence of infants against infanticide. Female behaviour is best explained by resource defence.

The structure, context and possible functions of solos, duets and choruses in the subdesert mesite (Monias benschi)

Abstract: Subdesert mesites produced five distinct types of vocal element which they combined to produce two broad classes of song 'syllable'. One of these syllables was exclusive to males and the other was mainly given by females. Song syllables were either produced in series by single individuals to give solo songs, or 2-5 five birds vocalised simultaneously with varying degrees of temporal precision to give duets and choruses. Pair-duets were the most common and male solos the least common form of song recorded. Females initiated and terminated significantly more songs than males and male syllables followed female syllables more promptly than the converse. However, the syllable structure of male and female solos changed when synchronised to form pair-duets indicating that, in contrast to most previous studies of duetting species, these songs are a function of both male and female behaviour. Only a subset of each group contributed to duets and choruses and participation was positively correlated with mass for males and females both within and across groups. Song activity remained at a low but relatively constant rate throughout both the day and season. The wide variety of contexts in which songs were produced indicated that they serve multiple functions: some appear to be cooperative endeavours (e.g. to maintain contact in dense vegetation and to defend territories), others may be underpinned by conflicts and could function in matedefence or in inter- and intra-sexual assessment within groups.

Behavioural and cognitive influences of kairomones on an araneophagic jumping spider

Abstract: In laboratory experiments, Portia fimbriata, an araneophagic salticid from Queensland, was influenced by olfactory and contact-chemical cues from Jacksonoides queenslandicus, an abundant salticid on which P.fimbriata preys. Four distinct effects were revealed: P.fimbriata (1) moved into and remained in the vicinity of J. queenslandicus, (2) performed undirected leaping, behaviour known to function as speculative hunting by inducing a turning response from not-yet-seen J. queenslandicus, (3) adopted a posture (retracted palps) known to be routine when stalking salticids and (4) showed enhanced attention to optical cues from J. queenslandicus. Laboratory experiments provided no statistical evidence that chemical cues from other prey species affected P.fimbriata, that J. queenslandicus was affected by chemical cues from P. fimbriata or that allopatric Portia were sensitive to chemical cues from J. queenslandicus.