Showing papers in "Behaviour in 2015"

Coalitions in theory and reality: a review of pertinent variables and processes

Abstract: Coalitions and alliances are ubiquitous in humans and many other mammals, being part of the fabric of complex social systems. Field biologists and ethologists have accumulated a vast amount of data on coalition and alliance formation, while theoretical biologists have developed modelling approaches. With the accumulation of empirical data and sophisticated theory, we are now potentially able to answer a host of questions about how coalitions emerge and are maintained in a population over time, and how the psychology of this type of cooperation evolved. Progress can only be achieved, however, by effectively bridging the communication gap that currently exists between empiricists and theoreticians. In this paper, we aim to do so by asking three questions: (1) What are the primary questions addressed by theoreticians interested in coalition formation, and what are the main building blocks of their models? (2) Do empirical observations support the assumptions of current models, and if not, how can we improve this situation? (3) Has theoretical work led to a better understanding of coalition formation, and what are the most profitable lines of inquiry for the future? Our overarching goal is to promote the integration of theoretical and field biology by motivating empirical scientists to collect data on aspects of coalition formation that are currently poorly quantified and to encourage theoreticians to develop a comprehensive theory of coalition formation that is testable under real-world conditions.

Why do wild bonobos not use tools like chimpanzees do

Abstract: One of the most conspicuous behavioural differences among great apes is the paucity of tool use among wild bonobos (Pan paniscus) in comparison to chimpanzees (Pan troglodytes) who are one of the most prolific and skilled tool users in the animal kingdom. This is in spite of the fact that bonobo tool use repertories are as large and diverse as chimpanzees’ in captive settings. In this study, we compared tool using behaviours and potential drivers of these behaviours in the Wamba bonobo population located in central Democratic Republic of Congo with the Goualougo chimpanzee population of northern Republic of Congo. The tool use repertoire of wild bonobos was comprised of only 13 behaviours, compared to 42 for chimpanzees. However, the number of tool behaviours observed in each study site was similar between bonobos and chimpanzees, and many types of tool use for social, self-grooming/stimulation, and comfort/protection functions were commonly used by both species. A marked difference is that 25 of 42 tool behaviours exhibited by chimpanzees are performed for feeding, in contrast to a single report of bonobos using a leaf sponge to drink water. We examined whether the differences in tool use repertoires can be explained by the necessity, opportunity, relative profitability, or invention hypotheses. We found that habitat composition and fluctuation of fruit production at these two sites were similar, particularly when compared with variation observed between sites within each species. Thus it was unlikely that the necessity hypothesis explains the lack of tool use for feeding in bonobos. Though further study at Wamba is needed, we did not identify any obvious differences in prey availability that would indicate differences in tool using opportunities between the sites. This study could not test the relative profitability hypothesis, and further research is needed on whether tool use is the most efficient means of calorie or protein intake for wild apes. Bonobos at Wamba formed much larger and stable parties than chimpanzees at Goualougo, which was contrary to the prediction by the invention hypothesis. Another explanation is that differences in tool use behaviour between bonobos and chimpanzees might not be explained by the current ecological or social conditions, but rather by circumstances during the Pleistocene Epoch. The observed species differences might also reflect divergent behavioural predispositions, rather than actual differences in cognitive abilities.

Behavioural responses of ungulates to indirect cues of an ambush predator

Abstract: Ambush predators provide more persistent cues of predation risk compared to coursing predators and are predicted to exert stronger effects on behaviour of their prey. We studied anti-predator responses of ungulates by means of camera traps to an olfactory cue (fresh scat) of an ambush predator, the Eurasian lynx ( Lynx lynx). Roe deer ( Capreolus capreolus) and red deer ( Cervus elaphus) both important prey species for lynx were not more vigilant when exposed to lynx scent, but reduced their visitation duration. Our results contrast with previously reported responses of red deer to scent from a coursing predator, the wolf ( Canis lupus), where only vigilance and foraging behaviour but not visitation duration changed in response to wolf scat. This indicates that ungulates are able to recognize the risk of predation from predators with differing hunting modes based on olfactory cues and adjust their anti-predatory behaviour.

Black bear marking behaviour at rub trees during the breeding season in northern California

Abstract: We studied the marking behaviour of American black bears ( Ursus americanus) during the breeding season 2013. Six remote video cameras captured 529 trapping nights. We collected behaviour, sex, and age class of bears rubbing on trees. Marking events ( N = 31 ) were observed between 26 April and 27 July with a median of 12 June. The majority (96%) of marking events were performed diurnally. All bears we could accurately identify to sex were males ( N = 16 ) and 29 of 31 marking bears were adults. The most frequent use of contact with substrate was bipedal marking followed by pede marking, quadrupedal marking. Bears used their back, neck, head, and cheeks in nearly 90% of observations while scratching and biting occurred in less than a third of observations. We documented the novel behaviour ‘groin marking’. This study suggests rub trees are locations for chemical communication through a variety of marking techniques in forested environments.

Non-reciprocal but peaceful fruit sharing in wild bonobos in Wamba

Abstract: Food sharing is considered to be a driving force in the evolution of cooperation in human societies. Previously postulated hypotheses for the mechanism and evolution of food sharing, e.g., reciprocity and sharing-under-pressure, were primarily proposed on the basis of meat sharing in chimpanzees. However, food sharing in bonobos has some remarkably different characteristics. Here I report details pertaining to fruit sharing in wild bonobos in Wamba based on 150 events of junglesop fruit sharing between independent individuals. The bonobos, primarily adult females, shared fruit that could be obtained individually without any cooperation or specialized skills. There was no evidence for reciprocal exchange, and their peaceful sharing seems to contradict the sharing-under-pressure explanation. Subordinate females begged for abundant fruit from dominants; this might indicate that they tested the dominants’ tolerance based on social bonds rather than simply begging for the food itself, suggesting existence of courtesy food sharing in bonobos.

The effect of hunger on the exploratory behaviour of shoals of mosquitofish Gambusia holbrooki

Abstract: The question of how hunger affects locomotory behaviour, in particular how it affects the kinematics of movement and an animal’s interaction with the physical structures in its environment is of broad relevance in behavioural ecology. We experimentally manipulated the hunger levels of individual mosquitofish ( Gambusia holbrooki ) and recorded their swimming behaviour in shoals of 4 fish. We found that hungry individuals in shoals moved at greater speeds and had higher turning speeds than satiated individuals in shoals, as well as a greater variance in speed and turning speeds. We also found that hungry individuals explored more of the arena and used more of its internal space, away from the square arena’s walls and displayed less wall-following behaviour than satiated individuals. A functional explanation for this change in swimming behaviour and interaction with environmental heterogeneity is discussed in the context of social foraging, as is the consequence of these results for models of search patterns and collective movement.

Early-life nutritional stress affects associative learning and spatial memory but not performance on a novel object test

Abstract: Developmental environments can have long-term effects on cognition. Multiple aspects of cognition may be affected by unfavourable conditions during development if underlying neuronal structures are maturing simultaneously. We investigated the effects of nutritional stress at different stages of development on adult associative learning, spatial memory, and behaviours towards a novel object in a songbird. Zebra finches (Taeniopygia guttata) were raised in consistently high or low food conditions until post-hatch day (PHD) 36 (i.e., nutritional independence), where half of the birds from each condition were switched to the other condition until PHD 61. Subjects were then tested as adults with two associative learning tasks, a hippocampus-dependent spatial memory task, and for responses toward a novel object. Surprisingly, low food treatment before independence facilitated spatial associative learning but impaired an aspect of hippocampus-dependent spatial memory. Responses to a novel object were not altered by treatments. This study demonstrates that developmental stress is able to influence learning without simultaneously affecting a measure of personality.

Prolonged maximal sexual swelling in wild bonobos facilitates affiliative interactions between females

Abstract: Perineal sexual skin swelling in relation to menstrual cycle occurs in a variety of primate taxa. However, sexual swelling with exaggerated size and colour is found only in some Old World monkeys and the two Pan species. Although several hypotheses have been proposed (e.g., reliable indicator hypothesis and graded signal hypothesis), it seems unlikely that a single explanation can account for the significance of the sexual swelling in all of these species. Bonobos (Pan paniscus) provide an excellent opportunity for studying sexual swelling since they have the most prolonged maximal swelling periods among primates. In this study we propose a new hypothesis that sexual swelling in female bonobos increases their attractiveness to other females and thereby facilitates affiliative social interaction with them. We found that free-ranging female bonobos with maximal sexual swelling engaged in affiliative social interactions with other females, including genito-genital rubbing, staying in close proximity and grooming, more frequently than females without maximal swelling. These tendencies suggest that females with maximal swelling were attractive to other females. The results also suggest that the benefits of maximal swelling might vary among females depending on their life-history stage. In particular, young females may get more benefits from prolonged maximal swelling through increased grooming reciprocity and staying in close proximity to other females. Thus our study supported the hypothesis that one function of prolonged maximal swelling in bonobos is to increase attractiveness to other females, thereby enhancing affiliative relationships between females in a male-philopatric social system.

Sex and strife: post-conflict sexual contacts in bonobos

Abstract: Sexual contacts are thought to play an important role in regulating social tension in bonobos (Pan paniscus), and are especially common following aggressive conflicts, either between former opponents or involving bystanders. Nevertheless, research on the factors determining post-conflict sexual contacts, their effectiveness in reducing social tension and the nature of post-conflict sexual behaviour is scarce. Here, we collected data on post-conflict affiliative contacts in bonobos occurring between former opponents (reconciliation) and offered by bystanders towards victims (consolation) to investigate the role of sexual contacts in the regulation of aggressive conflicts compared to non-sexual affiliation behaviours. We tested whether post-conflict sexual contacts: (1) alleviate stress, (2) confer reproductive benefits, (3) mediate food-related conflict and (4) repair valuable social bonds. Thirty-six semi-free bonobos of all ages were observed at the Lola ya Bonobo Sanctuary, DR Congo, using standardized Post-Conflict/Matched Control methods. Consolation and reconciliation were both marked by significant increases in the occurrence of sexual behaviours. Reconciliation was almost exclusively characterized by sexual contacts, although consolation was also characterized by increases in non-sexual behaviours, such as embrace. Adults were more likely to engage in post-conflict sexual contacts than younger bonobos. Consistent with the stress-alleviation hypothesis, victims receiving sexual consolatory contact showed significantly lower rates of self-scratching, a marker of stress in primates, compared to receiving non-sexual contact. Post-conflict sexual contacts were not targeted towards valuable social partners and they did not confer obvious reproductive benefits; nor were they used to mediate food-related conflicts. Overall, results highlight the role of sex in regulating tension and social conflicts in bonobos.

Changes in wild red squirrel personality across ontogeny: activity and aggression regress towards the mean

Abstract: Both juvenile and adult animals display stable behavioural differences (personality), but lifestyles and niches may change as animals mature, raising the question of whether personality changes across ontogeny. Here, we use a wild population of red squirrels to examine changes in activity and aggression from juvenile to yearling life stages. Personality may change at the individual level (individual stability), population level (mean level stability), and relative to other individuals (differential stability). We calculated all three types of stability, as well as the structural stability of the activity–aggression behavioural syndrome. Within individuals, both activity and aggression scores regressed towards the mean. Differential stability was maintained for activity, but not aggression. Structural stability was maintained; however, the activity–aggression correlation increased in squirrels that gained territories later in the season. These results suggest that personality undergoes some changes as animals mature, and that the ontogeny of personality can be linked to environmental changes.

Host behaviour, age and sex correlate with ectoparasite prevalence and intensity in a colonial mammal, the little brown bat

Abstract: The influence of behaviour on host-parasite dynamics has theoretical support but few empirical studies have examined this influence for wild-captured hosts, especially in colonial species, which are thought to face generally high risk of exposure. Behavioural tendencies of hosts in novel en- vironments could mediate host exposure. We tested the hypothesis that behavioural tendencies of hosts, and host sex and age, correlate with prevalence and intensity of ectoparasites in a gregarious mammal, the little brown bat (Myotis lucifugus). We also tested whether relationships between host behaviour and parasite prevalence and intensity would vary between taxa of ectoparasites which differ in host-seeking behaviour. We predicted that individual hosts displaying active and explo- rative behaviours would have higher prevalence and intensity of parasites that depend on physical contact among hosts for transmission (mites) but that host behaviour would not influence preva- lence and intensity of mobile ectoparasites with active host-seeking behaviour (fleas). We recorded behavioural responses of wild-captured bats in a novel-environment test and then sampled each individual for ectoparasites. After accounting for age and sex we found mixed support for our hy- potheses in some but not all demographics. More active adult and young of the year (YOY) males were more likely to host mites while more active adult and YOY females were less likely to host fleas. Our results highlight possible differences in the influence of host and parasite behaviour on parasite transmission dynamics for colonial compared to non-colonial species and have conserva- tion implications for understanding pathogen transmission in bat white-nose syndrome and other wildlife diseases.

Cultural evolution of killer whale calls: background, mechanisms and consequences

Abstract: Cultural evolution is a powerful process shaping behavioural phenotypes of many species including our own. Killer whales are one of the species with relatively well-studied vocal culture. Pods have distinct dialects comprising a mix of unique and shared call types; calves adopt the call repertoire of their matriline through social learning. We review different aspects of killer whale acoustic communication to provide insights into the cultural transmission and gene-culture co- evolution processes that produce the extreme diversity of group and population repertoires. We argue that the cultural evolution of killer whale calls is not a random process driven by steady error accumulation alone: temporal change occurs at different speeds in different components of killer whale repertoires, and constraints in call structure and horizontal transmission often degrade the phylogenetic signal. We discuss the implications from bird song and human linguistic studies, and propose several hypotheses of killer whale dialect evolution.

Elevation related variation in aggressive response to mirror image in mountain chickadees

Abstract: Behavioural syndrome literature suggests that behavioural traits may be coupled to form behavioural strategies that are consistent and repeatable across contexts. Typically these behavioural types are composed of bold, aggressive, dominant individuals and shy, less aggressive, subordinate individuals. Mountain chickadees living in varying climatic conditions across a montane environment appear to exhibit consistent behavioural types, such that high elevation birds, which experience harsher winter conditions and rely more heavily on spatial memory to retrieve food caches to survive winter, explore a novel environment at a slower rate (i.e., shy) and are socially subordinate to low elevation birds. Dominance is typically expressed in individual pairwise interactions, but it is not always clear which traits predispose an individual to become a dominant in such interactions. Aggression is frequently suggested to be associated with higher dominance status, yet the data are equivocal. Here we aimed to test whether previously described elevation related differences in social dominance might be associated with elevation related differences in aggression levels in mountain chickadees by using the mirror test. The mirror test can address potential differences in reactive and proactive aggression, although caution should be taken when using the mirror test as some species are able to self-recognize. Low elevation birds responded more aggressively to their mirror image than high elevation birds, suggesting that elevation related differences in aggression may be partially responsible for previously found differences in social dominance status.

Changes to web architecture of Leucauge volupis (Araneae: Tetragnathidae) induced by the parasitoid Hymenoepimecis jordanensis (Hymenoptera: Ichneumonidae)

Abstract: Some new cases of ectoparasitoid wasps from the Polysphincta genus-group manipulating the behaviour of host spiders have been described in recent years, indicating that the modification of normal web structure is the rule rather than an exception as the outcome of these interactions. In most cases, orb web diameter and the number of adhesive spirals are reduced, which decreases the probability of web damage from the interception of insects on the viscid threads during the development of the parasitoid within the cocoon. In this study, we describe a new interaction between the host spider Leucauge volupis and the recently described parasitoid Hymenoepimecis jordanensis. Web modifications induced by larvae in their last instar, in this case, are different to those described for two other Leucauge species attacked by Hymenoepimecis spp., L. argyra and L. roseosignatha. The cocoon webs constructed by the parasitized L. volupis are similar to those webs constructed by immature individuals, presenting a lower tangle, which may increase the stability of the web or offer additional physical protection for the cocoon. As in other previously described cases, sticky spirals are absent from cocoon webs. However, the photographs of webs constructed by spiders carrying second instar larvae indicated that the reduction in spirals begins before the construction of the cocoon web. These webs remain functional, being substantially modified only when the larvae reach the third instar. Variation among cocoon web designs of congeneric hosts attacked by distinct Hymenoepimecis species indicate that the substance used for host manipulation may vary in concentration and/or composition. Alternatively, distinct host responses may occur to the same substances.

Preference or paradigm? Bonobos show no evidence of other-regard in the standard prosocial choice task

Abstract: Bonobos are the only ape species, other than humans, that have demonstrated prosocial behaviors toward groupmates and strangers. However, bonobos have not been tested in the most frequently used test of prosociality in animals. The current study tested the other-regarding preferences of bonobos in two experiments using the prosocial choice task. In the first experiment subjects preferred a food option that would benefit both themselves and another bonobo. This preference was likely the result of a location bias developed in the pretest since they showed the same preference in the non-social control condition within test sessions. A second experiment was designed to help subjects overcome this bias that might interfere with their social choices. Bonobos again did not prefer to choose the prosocial option. However, results suggest constraints of this paradigm in revealing social preferences. In discussing our results we consider why bonobos show robust prosocial preferences in other paradigms but not here. While others have suggested that such contradictory results might suggest interesting motivational or cognitive differences between humans and non-humans, we propose that the current ‘standard’ paradigm has failed validation due to three methodological constraints. Across the dozens of studies completed few have demonstrated that non-human subjects understand the causal properties of the apparatus, non-social biases quickly develop in inadequately counterbalanced pretests that typically explain subjects’ choices in the test, and even human children found this choice task too cognitively demanding to consistently show prosocial preferences. We suggest it is time to consider switching to a variety of more powerful and valid measures.

Dominance relationships in a group of domestic dogs (Canis lupus familiaris)

Abstract: We investigated the extent to which dominance relationships, as described for feral dogs and wolves, applied to a group of 24 neutered companion dogs at a dog daycare facility. Similar to other studies of dogs and wolves, we found significant linear dominance hierarchies based on highly unidirectional displays of submission and aggression. Submission was the most frequent, unidirectional and linear type of agonistic behaviour and, therefore, a better indicator of status than aggression or dominance displays. Aggression was low intensity, consisting mainly of ritualized threats with no physical contact, and conflicts involving physical contact were never injurious. Older dogs out-ranked younger dogs, but size was unrelated to dominance rank. Dominance relationships were more often expressed in same-sex dyads than between males and females. The coverage of dominance relationships in the daycare group was low compared to that reported for sexually intact dogs and wolves, which was probably a result of reduced competition due to neutering and other human influences. In many dyads dogs never exchanged agonistic behaviours, but bi-directional relationships were rare, and most dogs formed some dominance relationships with other dogs. Except for their low coverage, muzzle licks met the criteria for a formal display of submission. Our results suggest that dominance remains a robust component of domestic dog behaviour even when humans significantly reduce the potential for resource competition. The possible proximate benefits of dominance relationships for dogs are discussed.

Oxytocin reduces food sharing in capuchin monkeys by modulating social distance

Abstract: Recent evidence indicates that oxytocin plays an important role in promoting prosocial behaviour amongst humans and other species. We tested whether oxytocin affected cooperation and food-sharing in capuchin monkeys, a highly cooperative New World primate. Subjects received either 2IU oxytocin or an inert adjuvent intranasally prior to each session. Oxytocin influenced food sharing in capuchins in ways we did not anticipate. Recipients were less likely to passively acquire food from possessors when either individual had received OT than in the control, and also spent less time in proximity to their partner. Passive food sharing requires proximity, and oxytocin decreased the capuchins’ typical congregating behaviour, apparently resulting in decreased sharing. We propose that the likely mechanism for increased social distance is the known anxiolytic effect of oxytocin. Our results indicate a need to consider how oxytocin affects the context of interactions and interacts with modes of sociality unique to each species.

Oriental reed warbler (Acrocephalus orientalis) nest defence behaviour towards brood parasites and nest predators

Abstract: Brood parasites and predators pose different threats to passerines that may favour the evolution of enemy-specific defence strategies. Furthermore, potential sex-specific variation in parental investment may be manifested in differences between male and female nest defence behaviour. We investigated these hypotheses in Oriental reed warblers ( Acrocephalus orientalis), by recording sex- and stage-specific (nests with eggs or nestlings) responses to stuffed dummies placed at their nests. Warblers showed the highest level of aggression to the co-occurring parasite, the common cuckoo ( Cuculus canorus), colour morph (grey), but showed reluctance to mob or attack the co-occurring nest predator, the magpie ( Pica pica). There was a sex difference in rate of body attacks towards rufous morph common cuckoo, sparrowhawk ( Accipiter nisus) (locally absent parasite and predator, respectively) and the spotted dove ( Streptopelia chinensis) (locally present, harmless species), with females showing better ability to distinguish between these species than males.

Nonapeptide influences on social behaviour: effects of vasotocin and isotocin on shoaling and interaction in zebrafish

Abstract: Nonapeptides are important regulators of social behaviour across vertebrate taxa. While their role in simple grouping behaviour has been explored in estrildid finches, other taxa are understudied, prompting us to investigate nonapeptide influences on shoaling behaviour in zebrafish. Subjects received injections of isotocin, an isotocin antagonist, vasotocin, a vasotocin antagonist, or saline, followed by a test of grouping behaviour. Vasotocin decreased social interaction with the shoal. Unexpectedly, the vasotocin antagonist also reduced social interaction with the shoal, as well as general shoaling behaviour. Isotocin and its antagonist had minimal effects on grouping behaviours. These results suggest social interaction and shoaling are discrete aspects of sociality differentially influenced by vasotocin, although we cannot discount possible anxiogenic effects of vasotocin. Contrasting these results with studies in other systems demonstrates that each nonapeptide’s role in social behaviour varies across taxa, and cautions against a simplistic characterisation of nonapeptides as prosocial regulators of behaviour.

Allonursing in white-faced capuchins (Cebus capucinus) provides evidence for cooperative care of infants

Abstract: Allonursing is a highly cooperative behaviour that may have important fitness consequences for the infant while the benefits to the allomother are less clear. To investigate the function of this behaviour, we compared patterns of allonursing and nursing exhibited by white-faced capuchin monkeys ( Cebus capucinus). We used a linear mixed model approach to analyse data collected on 21 infants from six social groups in Sector Santa Rosa, Costa Rica. Infants nursed at higher rates and for longer durations from their mothers than from allonurses. They also allonursed at higher rates from lactating and non-lactating parous females than from nulliparous females and at higher rates from maternally related female allonurses than other females. We found no observed effect of adult female rank or infant sex. We conclude that infant white-faced capuchins engage in allonursing as a means to acquire additional milk, and that participating allonurses may benefit from increased inclusive fitness.

Evidence for assessment disappears in mixed-sex contests of the crayfish, Orconectes virilis

Abstract: During agonistic interactions, decisions about contest persistence can be informed by assessment of one’s own energy or time expenditure (self-assessment), one’s own expenditure combined with opponent inflicted costs (cumulative assessment), or through information exchange with an opponent (mutual assessment). Females and males can be expected to exhibit different strategies for contest resolution due to contrasting energetic requirements and resource valuation. We examined the assessment strategies crayfish employ during same-sex and mixed-sex fights. Two individuals interacted for 15 min, and fight duration and times spent at various intensity levels were quantified. Results indicated that both sexes employ a self-assessment strategy during same-sex fights. Evidence for assessment during mixed-sex fights was notably weaker, suggesting the resolution of mixed-sex fights involves different behavioural elements and/or sources of information. In species where mixed-sex fights are common year-round, the lack of common rules can lead to greater energy expenditure for both sexes.

Recognition of familiarity on the basis of howls: a playback experiment in a captive group of wolves

Abstract: Playback experiments were conducted with a pack of captive Iberian wolves. We used a habituation–discrimination paradigm to test wolves’ ability to discriminate howls based on: (1) artificial manipulation of acoustic parameters of howls and (2) the identity of howling individuals. Manipulations in fundamental frequency and frequency modulation within the natural range of intra-individual howl variation did not elicit dishabituation, while manipulation of modulation pattern did produce dishabituation. With respect to identity, across trials wolves habituated to unfamiliar howls by a familiar wolf (i.e., no direct contact, but previous exposure to howls by this wolf), but not to unfamiliar howls from unfamiliar wolves (i.e., no direct contact and no previous exposure to howls by these wolves). Modulation pattern seems to be an important bioacoustic feature for individual recognition. Overall, our results provide the first experimental evidence that wolves can discriminate individuals based on the acoustic structure of their howls.

Risk in a changing world: environmental cues drive anti-predator behaviour in lake sturgeon (Acipenser fulvescens) in the absence of predators

Abstract: Rapidly changing climates and habitats represent challenges faced by the majority of animal species on our planet, and are leading to rapid declines in global biodiversity. However, the degree to which behaviour is influenced by changing environmental cues is not well understood. Specifically, environmental cues that have been correlated with predator abundance or performance over evolutionary history may have significant effects on prey behaviour. In the present study, we investigated the role of water clarity on foraging activity in lake sturgeon (Acipenser fulvescens) in the absence of predators. Foraging activity was significantly higher during the night than the day and was higher in turbid environments versus clear environments, indicating that decreased turbidity alone, may in part drive anti-predator behaviour and constrain foraging activity. Future work exploring the interconnectedness of environmental cues and behavioural changes will help us better understand the many ways rapidly changing environments can influence behavioural ecological processes.

Testing the predation stress hypothesis: behavioural and hormonal responses to predator cues in Allegheny Mountain dusky salamanders

Abstract: The predation stress hypothesis posits that exposure to predators and/or predator cues causes release of glucocorticoid hormones which coordinate behavioural responses that facilitate predator avoidance. We measured responses to short-term and repeated exposure to predator-derived kairomones in Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus). Salamanders expressed predator avoidance behaviours (reduced locomotion, reduced mating behaviour) in the presence of predator kairomones. However, plasma glucocorticoids after short-term exposure to predator kairomones were similar to levels after exposure to controls. After repeated exposure to predator-derived kairomones, locomotory activity and plasma glucocorticoids were similar compared to controls. There was no evidence of habituation to predator kairomones. Overall, results did not support the predation stress hypothesis in Allegheny Mountain dusky salamanders in either an acute or chronic context. Use of glucocorticoids to mediate antipredator responses may occur when predation pressure is unpredictable, and when energetic and opportunity costs of linking glucocorticoids to anti-predator responses are low.

Mate detection and seasonal variation in stick insect mating behaviour (Phamatodea: Clitarchus hookeri)

Abstract: For animals that exhibit a scramble competition mating system, sexual selection pressures on mate searching ability are expected to be strong Scramble competition mating systems evolve when populations provide females with equal accessibility to all male competitors, yet sex ratio and population density influences mating systems and varies seasonally The stick insect species, Clitarchus hookeri, is frequently found in copula, yet very little is known about it’s mating behaviour We preformed behavioural tests and assayed antennal sensory morphology to determine whether males used chemosensory cues to detect females Through natural field observations we found populations to be significantly male-biased earlier in the season, while later, populations began to display equal sex ratios With increasing female availability mating pair proportions steadily increased, while copulation duration declined These results support C hookerias a scramble competitor, and demonstrate males may alter their behaviour in response to the seasonal variation in female density

Behavioural syndrome in juvenile eels and its ecological implications

Abstract: Behavioural syndrome, which refers to a suite of correlated behaviours across differing situations, has been identified in numerous animals, including fish. The presence and conservation of a behavioural syndrome throughout evolutionary times suggests it confers various advantages at a population level. In eels, such as the European eel (Anguilla anguilla), activity and aggressiveness are important factors in their life history, since both traits influence dispersal and territoriality. In the present study we investigated whether these behavioural traits were consistent at both the nychtemeral scale (24 h) and over a long time period (7 months). In addition, we investigated if aggressiveness and activity were positively correlated. Both activity and aggressiveness were significantly repeatable, indicating that both behavioural traits could be considered as personality traits. Interestingly, nocturnal activity was correlated to diurnal activity, indicating that this personality trait was highly stable at the circadian scale. Both aggressiveness and activity were correlated in the course of the experiment, underlining the presence of a behavioural syndrome. The detection of two behaviourally distinct groups in juvenile eels: aggressive and active individuals versus their counterpart have implications in the understanding of the colonization profile of the watershed. We discuss these findings in relation to the ecology of this species.

Behavioural persistence during an agonistic encounter differentiates winners from losers in green anole lizards

Abstract: Agonistic encounters featuring ritualized displays precede the establishment of dominance relationships in many animals. We investigated the predictive value of the amount of display behaviour (number and duration of displays) vs. quickness to display (latency to express a display behaviour) in determining the outcome of aggressive interactions and establishment of dominant vs. subordinate status in male green anole lizards, Anolis carolinensis. Similar-sized males were paired and observed for ninety minutes as they established social status. We recorded the number, duration (where appropriate) and latencies to first expression for multiple behavioural display components (head bob A, B and C, dewlap displays, open mouth displays, pushups, lateral displays) and colour changes (eyespot presence and body colour changes). Males that eventually won and became the dominant male had significantly higher counts and durations with the exception of Bob C counts, pushup counts and open mouth duration. Future dominants also maintained a green body colour longer than future subordinates, which had brown shades more often and for longer durations. Latency to first express a display component was shorter in future dominants for head bobs A and C, dewlap and open mouth displays when all data were considered. However, all significant latency differences disappeared when data only from pairs in which both males displayed a behaviour were included in the analysis. Counts, durations, and latencies were highly correlated with each other within individuals. The results indicate that behavioural display patterns during an initial display contest predict the outcome of the interaction, with the amount of display behaviour being the best predictor of whether a male will win or lose the contest and hence become dominant or subordinate. These results are consistent with the idea that displays are honest signals of a male’s physiological capacity or stamina, and hence fighting and resource holding ability.

Genetic relatedness in two-tiered plains zebra societies suggests that females choose to associate with kin

Abstract: How kinship structures alter inclusive fitness benefits or competition costs to members of a group can explain variation in animal societies. We present rare data combining behavioural associations and genetic relatedness to determine the influence of sex differences and kinship in structuring a two-tiered zebra society. We found a significantly positive relationship between the strength of behavioural association and relatedness. Female relatedness within herds was higher than chance, suggesting that female kin drive herd formation, and consistent with evidence that lactating females preferentially group into herds to dilute predation risk. In contrast, male relatedness across harems in a herd was no different from relatedness across herds, suggesting that although stallions benefit from associating to fend off bachelors, they do not preferentially form kin coalitions. Although both sexes disperse, we found that most harems contained adult relatives, implying limited female dispersal distances and inbreeding in this population, with potential conservation consequences.

Spatial pattern of syllable sharing in white-throated thrushes: implications for song learning and dispersal behaviours

Abstract: The relationship between song sharing among male songbirds and geographic distance between their territories is a function of juvenile dispersal distance and length of the song learning period. I analysed the spatial pattern of syllable sharing in white-throated thrushes (Turdus assimilis )t o infer their song learning strategy. Songs of 23 males from three different sites (2.5-21 km) in Puntarenas, Costa Rica, were studied using visual classification, spectrogram correlation and mul- tidimensional scaling analysis. In total, 8505 syllables were classified into 296 syllable types. All males shared syllables but most types were unique to particular males, suggesting that males invent most of their repertoires. Repertoire dissimilarity increased with geographic distance. Within sites, syllable sharing was higher between intermediate than between adjacent neighbours. These results suggest that juvenile dispersal distance is <2.5 km and relatively lower song sharing between adja- cent neighbours may result from non-random dispersal or active avoidance by open-ended learners.

Chemical caressess: geographical variation of male sexual signals in a Neotropical scorpion

Abstract: Differences in sexual signals among species are common, and may influence mate recognition and reproductive isolation. In scorpions, behavioural mechanisms and other sexual signals involved in mate selection and reproductive isolation have been scarcely studied. In this paper, we compare different male sexual signals between two distant populations of the scorpion Bothriurus bonariensis , one located in Uruguay and the other in Central Argentina. We compare sexual behaviours from intra-populations and inter-populations matings. In addition, we extent this comparison to the secreted compounds and morphology of the exocrine glands located on the dorsal side of the telson in this species. Males of B. bonariensis performed stimulatory behaviours to the female with different frequency of occurrence and duration in the two populations. Chemical analyses of the glandular extracts showed that Uruguayan males present compounds which are absent in males of Argentinian population. In addition, we observed that in inter-population matings, stimulatory behaviours had intermediate patterns to intra-population matings. However, males failed to achieve a successful sperm transfer with females of different population. Mechanisms of sexual isolation between these two distant populations of B. bonariensis apparently seem to have evolved due to divergence in allopatry. The differences in stimulatory levels during courtship between the two populations studied here give evidence for an early behavioural divergence promoted by sexual selection.