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Animal Behaviour
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  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0003-3472 - ISSN (Online) 1095-8282
Published by Elsevier Homepage  [3181 journals]
  • Mechanism for establishing and maintaining the reproductive hierarchy in a
           eusocial mammal, the Damaraland mole-rat
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): John B. Kelley, Sara N. Carter, Bruce D. Goldman, Sharry Goldman, David A. FreemanEusociality is exhibited by colonial-living organisms where only a few individuals within a colony reproduce; the remaining members are nonbreeders and support reproduction of the breeders. Damaraland mole-rats, Fukomys damarensis, are one of two mammal species considered eusocial. Colonies include a breeding pair and their offspring. Unusual aspects of reproductive behaviour include the observation that both sexes display all components of mating even after long-term absence of gonadal hormones. Mating does not occur between siblings or offspring and parents, but nonbreeders from one colony will mate with individuals from other colonies. However, following 5 weeks of separation from each other, siblings will exhibit mutual sexual behaviour. Thus, familiarity through frequent proximity, rather than genetic identity, mediates inbreeding avoidance. One caveat is that breeding pairs maintain a mating relationship for years, although they obviously become familiar with each other. Among Damaraland mole-rats that are familiar with each other, two types of relationships can form, a mating relationship or a ‘sibling-like’ relationship marked by inbreeding avoidance. The factors determining the relationship between pairs of Damaraland mole-rats remain undefined. This experiment tested the hypothesis that the behaviour during the initial meeting of a pair of Damaraland mole-rats determines which relationship forms, i.e. mating versus ‘sibling-like’. The initial pairing occurred either with unrestrained physical contact (allowing for mating behaviours) or with the two animals separated from each other by a mesh barrier (no mating could occur). This initial pairing was followed by daily 20 min pairings with the barrier in place for 2 weeks and then a final pairing without any restraint. Results indicate that the nature of the interaction within the first 20 min of meeting determines the long-term sexual relationship between pairs of Damaraland mole-rats. The results suggest a mechanistic basis for establishment and maintenance of the reproductive hierarchy in this eusocial species.
       
  • Exposure to the ultraviolet filter benzophenone-3 (BP3) interferes with
           social behaviour in male Siamese fighting fish
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Kelley B. Portrais, Megan A. Stevens, Cassie N. Trask, Samantha N. Mundy, Jessica M. Szetela, Bronwyn H. Bleakley, Teresa L. DzieweczynskiOxybenzones like benzophenone-3 (BP3) are ultraviolet (UV) filters widely used in personal care products such as sunscreens. BP3 is currently receiving a great deal of attention because many of its properties, including high water solubility and potential to bioaccumulate, enable it to have damaging effects on aquatic ecosystems. One of these effects, the induction of coral bleaching, has led Hawaii to ban all sunscreens containing BP3. BP3 also appears to have endocrine-disrupting properties and has been found to affect animal physiology. However, behavioural consequences of BP3 exposure have yet to be thoroughly characterized. In the present study, we investigated the effects of BP3 on boldness, courtship and aggression in male Siamese fighting fish, Betta splendens, as little is known about the effects that BP3 has on fish social behaviour. To accomplish this, we assigned males to a treatment group (control, low, medium or high BP3 concentration) and completed individual (empty tank, novel environment and shoal) and social (courtship and aggression) behavioural assays before and after a 28-day exposure period. BP3 influenced the expression of social behaviours, with individual boldness generally unaffected. Changes in shoaling occurred regardless of BP3 concentration, while BP3-associated decreases in courtship and aggression were concentration dependent. Abnormal social behaviour may impede successful mating and alter territorial dynamics, with potentially heightened effects in species already experiencing other anthropogenic stressors.
       
  • Effects of artificial light at night and male calling on movement patterns
           and mate location in field crickets
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Eliza K. Thompson, Naomi L. Cullinan, Therésa M. Jones, Gareth R. HopkinsAnthropogenic factors, such as artificial light at night (ALAN), are increasingly linked to significant modifications in animal behaviours, such as foraging or migration. However, few studies have investigated directly whether the presence of ALAN affects the ability to find a mate (mate location). One direct effect of the presence of ALAN is that it can create a light barrier in an otherwise dark environment. This may have significant behavioural implications for nocturnally active species if it affects their ability to respond to potential mates. Our study, using the acoustically orienting Australian black field cricket, Teleogryllus commodus, determined experimentally whether the presence of a fragmented light environment influenced movement patterns of virgin females and males. Moreover, given the importance of male song for reproductive outcomes in this species, we assessed simultaneously whether such behaviours were modified by the presence of a male attraction call. We found that while initiation of movement was slower in the presence of ALAN, the behavioural shifts associated with its presence were relatively small compared to the influence of a broadcast male attraction call. The response to the male attraction call was typically stronger for females than for males, but both males and females modified aspects of behaviour when it was present regardless of whether their immediate environment was fragmented by artificial light at night or not. Artificial light at night may alter subtle aspects of movement and mating behaviour in this species, but ultimately does not provide a barrier to movement or mate location.
       
  • Perceived dominance status affects chemical signalling in the neriid fly
           Telostylinus angusticollis
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Zachariah Wylde, Lewis Adler, Angela Crean, Russell BondurianskyChemical communication mediates many social interactions in insects but is still less well understood than other forms of communication. In particular, chemical signalling of social dominance is believed to play an important role in competitive interactions in both sexes, but much of the evidence is correlational. Here we manipulated social dominance and examined its effect on CHC profiles in Telostylinus angusticollis, a fly with a resource defence polygyny mating system. Focal individuals' perception of their own dominance status was manipulated by placing them in an arena with larger or smaller competitors to render them ‘subordinate’ or ‘dominant.’ We found that social dominance treatment affected males' and females' social status (quantified as proximity to the larval medium/oviposition dish), as well as their CHC profiles. Dominant individuals tended to have CHC profiles less similar to those of the opposite sex. Moreover, dominant females exhibited an overall elevation of all CHC expression, relative to subordinate females, whereas males that perceived themselves as subordinate exhibited a near-significant downregulation of male-limited CHCs. Our findings suggest that T. angusticollis males and females alter their CHC profiles in response to their self-perceived social dominance status. These chemical signals could play a role in social interactions both within and between the sexes.
       
  • How does cognitive performance change in relation to seasonal and
           experimental changes in blood glucose levels'
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Celine Rochais, Audrey Maille, Jörg Jäger, Neville Pillay, Carsten SchradinIn some species, cognition can change flexibly in response to environmental changes. These changes can be adaptive or can result from physiological constraints, such as when energy availability decreases seasonally. Here, we investigated: (1) how cognitive performance changes between seasons that differ significantly in food availability; (2) how these changes are related to environmentally induced physiological changes (blood glucose); and (3) whether experimental increase in blood glucose levels during the dry season impacts cognitive performance. We studied 93 free-ranging African striped mice, Rhabdomys pumilio, in the Succulent Karoo, South Africa during the hot summer dry season with low food availability, and the cold wet winter with high food availability. Striped mice had reduced blood glucose levels during the food-restricted dry season. We measured their attention using the standardized orientation response test and their spatial memory using the Barnes maze test. Neither attention nor spatial memory changed seasonally. However, high basal and experimentally increased blood glucose levels impaired cognition in most cases. We also found sex differences in cognitive performance. Even though food was restricted in the dry season and blood glucose levels were reduced, cognition was not affected by these changes, indicating cognitive resilience, which represents an evolved adaptation to cope with seasonally changing energy supply in striped mice.
       
  • Affiliative social relationships and coccidian oocyst excretion in a
           cooperatively breeding bird species
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Claudia A.F. Wascher, Daniela Canestrari, Vittorio BaglioneIn group-living animals, behavioural interactions with conspecifics strongly modulate an individual's physiological stress response. Stable social relationships may reduce an individual's stress response, which in turn can affect the immune system and health. Ultimately, positive health effects of stable social bonds may contribute to maintaining group living. We investigated whether, in cooperatively breeding carrion crows, Corvus corone, the quality of social relationships correlates with the excretion of coccidian oocysts and nematode eggs. We repeatably collected behavioural data on dyadic social interactions and individual droppings to quantify parasite eggs and oocysts from 36 individuals in a captive population of carrion crows in northern Spain. Individuals with strong social bonds, living with more relatives and in larger groups, excreted a significantly smaller proportion of droppings containing coccidian oocysts. The probability of excreting droppings containing nematode eggs was not affected by social factors. The relationship between social interactions and coccidian oocyst excretion is consistent with the idea that high-quality social relationships can positively affect an individual's health, setting the stage for the evolution of stable social living.
       
  • A mismatch between signal transmission efficacy and mating success calls
           into question the function of complex signals
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Noori Choi, Mitch Bern, Damian O. Elias, Rowan H. McGinley, Malcolm F. Rosenthal, Eileen A. HebetsVariation in transmission characteristics of signalling environments is hypothesized to influence the evolution of signalling behaviour, signal form and sensory systems of animals. However, many animals communicate across multiple signalling environments, raising the possibility that some displays have evolved explicitly to enable communication across heterogeneous signalling environments. In the present paper, we explored multiple potential impacts of the signalling environment on courtship displays in the wolf spider Schizocosa retrorsa. Males of this species court females on a range of substrate types using a combination of vibratory and visual signals. Through a series of experiments, we investigated (1) activity patterns and male microhabitat use, (2) component-specific vibratory signal transmission across natural substrate types and (3) copulation success across substrate types and light levels. We found that, in the laboratory, (1) female and male S. retrorsa are most active during daylight hours, and mature males resided and courted most on leaf litter, as compared to their natural habitat types of pine litter or sand; (2) male vibratory courtship signals transmitted best on leaf litter, yet (3) males obtained the highest copulation success on sand, regardless of light level. Our results demonstrate that copulation in S. retrorsa is more likely to occur in environments with suboptimal vibratory signal transmission, irrespective of visual signal transmission. We suggest that these results point to (1) a minor role of bimodal (vibratory and visual) courtship signalling in S. retrorsa, (2) the importance of an additional signalling modality (most likely air particle movement), (3) a role of other substrate-dependent factors (e.g. predation risk), and/or (4) a reversed female preference for vibratory signalling.
       
  • Songbirds show odour-based discrimination of similarity and diversity at
           the major histocompatibility complex
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): L.A. Grieves, G.B. Gloor, M.A. Bernards, E.A. MacDougall-ShackletonThe major histocompatibility complex (MHC) is the most polymorphic region of the vertebrate genome. Individuals with more MHC alleles can respond to a broader suite of pathogens, suggesting that selection should favour the ability to assess the MHC genotype of potential mates. Indeed, MHC-based mate choice, particularly preferences for MHC-dissimilar or MHC-diverse partners, appears widespread among vertebrates. Mammals, fish and seabirds assess MHC through odour cues. However, despite the prominence of songbirds in mate choice studies, the mechanisms by which this group might assess MHC remain speculative. Motivated by the discovery that chemical similarity in the preen oil of song sparrows, Melospiza melodia, predicts similarity at MHC class II, we examined preen oil odour preferences for MHC dissimilarity and diversity. We presented breeding-condition song sparrows with preen oil from opposite-sex conspecifics using a two-choice design. We compared time spent with odour from MHC-dissimilar versus MHC-similar birds, and MHC-diverse versus less MHC-diverse birds. Both sexes spent more time with odour from MHC-dissimilar compared to MHC-similar birds and with odour from more MHC-diverse than less MHC-diverse birds. We conclude that song sparrows, and presumably other passerines, can use preen oil odour to discriminate MHC similarity and diversity of potential mates.
       
  • Adaptive plasticity of bushcricket acoustic signalling in socially
           heterogeneous choruses
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Marianna Anichini, Fran Rebrina, Klaus Reinhold, Gerlind U.C. LehmannIn many species, males produce sounds to attract a female. In a chorus, males actively adjust their acoustic production depending on the presence and number of mating rivals. Plasticity in signal features might then be advantageous as males could tune their signalling activity to the contest intensity. However, the ability to exhibit plastic behaviour might be constrained and interindividual variation in plasticity can occur. In this field study, we examined the influence of body mass and social environment on the signal expression of male bushcrickets, Poecilimon veluchianus veluchianus. We tested whether differences in signal features of rivals of different body mass and number led to changes in the competition pressure perceived by focal males and, consequently, in their acoustic responses. We used the first principal component from a principal component analysis, reflecting verse duration, duty cycle and syllable number, as a measure of acoustic output. We found that the rivals' acoustic output depended only on their number, being higher for two rivals than one. However, the response of heavy focal males depended on the rivals' body mass. Contrary to what we expected, heavy males produced shorter verses with fewer syllables when competing against two heavy rivals than when competing against one or two light rivals or one heavy rival. Facing light competitors, heavy focal males responded more to two rivals than to one. In contrast, light focal males did not vary their signal features depending on competition conditions. These results indicate that body mass and social context drive interindividual variation in the capacity of P. v. veluchianus males to adjust their signal features to competition levels. We compare these findings with those previously obtained on congeneric species and discuss the outcomes' similarities and discrepancies. Lastly, we provide suggestions for future studies of socially induced plasticity in sexually selected acoustic signal features.
       
  • Performance of Doppler shift compensation in bats varies with species
           rather than with environmental clutter
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Yu Zhang, Aiqing Lin, Jianan Ding, Xinyao Yang, Tinglei Jiang, Ying Liu, Jiang FengThe performance of vocal motor control is crucial for vocal communication; however, its evolution and ecological drivers are largely unknown. Doppler shift compensation (DSC), which has been found only in bats, represents an excellent model for studying the mechanisms and evolution of vocal control. We tested whether species that are more dependent on DSC for pulse–echo separation have a more precise DSC and whether changes in environmental clutter would result in adjustments in DSC performance. We recorded the echolocation and flight behaviour of the greater horseshoe bat, Rhinolophus ferrumequinum, and the great leaf-nosed bat, Hipposideros armiger, flying through a corridor and a window in turn. The DSC precision in H. armiger was significantly lower than that of R. ferrumequinum; the offset between the reference frequency and resting frequency, however, was not significantly different between the two species. We also studied the DSC of H. armiger flying through windows of different sizes. Their flight speed decreased significantly with reduced window size. However, DSC precision and the offset did not vary significantly with window size. Our results suggest that DSC is more precise in rhinolophids, which have a higher demand for pulse–echo separation by DSC, than in hipposiderids. Changes in environmental clutter do not necessarily result in adjustments of DSC performance. Functional importance associated with high-performance vocal control may be critical in shaping the precision of vocal control in the course of evolution. Instead, habitat clutter encountered by vocalizing animals may not play an important role.
       
  • Within-group relatedness and patterns of reproductive sharing and
           cooperation in the tropical chestnut-crested yuhina
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Sara A. Kaiser, Thomas E. Martin, Juan C. Oteyza, Julie E. Danner, Connor E. Armstad, Robert C. FleischerIn cooperatively breeding animals, genetic relatedness among group members often determines the extent of reproductive sharing, cooperation and competition within a group. Studies of species for which cooperative behaviour is not entirely based on kinship are key for understanding the benefits favouring the evolution and maintenance of cooperative breeding among nonrelatives. In the cooperatively breeding chestnut-crested yuhina, Yuhina everetti, a songbird endemic to Borneo, we tested whether unrelated helpers are more likely to gain parentage than are related helpers consistent with the hypothesis that inbreeding risk constrains reproduction by related helpers. We also examined whether related or unrelated helpers provision broods more because of differences in their potential indirect or direct fitness benefits of helping. Kin structure of breeding groups (breeding pair and up to eight helpers of both sexes, median = 2 helpers, 96% of 57 pairs had helpers) based on genetic analysis was mixed; 48% of 76 breeder/helper dyads were first-order (26%) or second-order (22%) relatives of one or both members of the breeding pair, and 52% were nonrelatives. Only unrelated male and female helpers gained parentage, and helpers did not differ in their provisioning rate according to their relatedness to the broods. We documented quasi-parasitism or co-breeding by female helpers in 14% of 29 broods and extrapair paternity by male helpers in 21% of 47 broods. This rate of extrapair paternity is relatively high among the few tropical species examined but fit with predictions for mixed-kin groups where inbreeding is avoided. These findings support the emerging pattern for cooperative breeding in birds with mixed-kin groups, wherein unrelated helpers are more likely to gain parentage than are related helpers and helping effort is not necessarily predicted by kinship.
       
  • Intermediate turbidity elicits the greatest antipredator response and
           generates repeatable behaviour in mosquitofish
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Sean M. Ehlman, Rebecca Halpin, Cameron Jones, Amelia Munson, Lea Pollack, Andrew SihIncreased turbidity, a common human-induced aquatic disturbance, can potentially have major impacts on predator–prey interactions via effects on key foraging and antipredator behaviours, on the repeatability of these behaviours (i.e. on animal personalities) and on behavioural syndromes (correlations among behaviours). Here, we repeatedly assayed individual western mosquitofish, Gambusia affinis, across a range of turbidity levels (low, intermediate, high) to test the degree to which a suite of behaviours (activity, exploration, sociality, responses to olfactory predator cues) scaled with increasing turbidity. In particular, we tested the a priori hypothesis, based on previous work, that fish show stronger behavioural repeatability and behavioural correlations when perceived predation risk is high. While individuals in all treatments responded to predator cues by reducing activity and exploration, those assayed in intermediate turbidity exhibited the strongest antipredator responses. Consistent with our prediction that repeatability should be greatest in high risk, significant behavioural repeatability was only detected in antipredator behaviours at intermediate turbidity. Significant correlations among behavioural traits were detected in all turbidity treatments but primarily under threat of predation – not when predator cues were absent (with one exception). This study demonstrates that levels of human-induced environmental change may interact with predation risk to shape both mean behavioural responses as well as patterns of behavioural correlations within and among individuals.
       
  • Impact of hybridization between sika and red deer on phenotypic traits of
           the newborn and mother–young relationships
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Uriel Gélin, Matthieu Keller, Victor de Beaupuis, Raymond Nowak, Frédéric Lévy, Yann LocatelliThe removal of pre-existing geographical barriers between species, notably by humans, allows previously isolated species to hybridize. Interspecies hybridization has been studied at different levels but the mother–young relationship, which is crucial for the offspring's survival, has not been investigated in large wild mammals. We compared the establishment of the mother–young relationship at birth and during the first week of life and the morphological development of the young in red deer, Cervus elaphus, sika deer, Cervus nippon, and their hybrids (male nippon × female elaphus). Most mother–young behaviours did not differ between the three groups, showing strong conservation of peripartum behaviours in cervids. In contrast, the behaviour and body size of the hybrid young were similar or tended to be close to those found in the maternal species, suggesting important maternal effects. In addition, hybrid young were more likely to be standing during the first week than young from the other groups, possibly resulting from increased maternal stimulation and/or hybrid vigour. Adult females in the herd were more likely to perform smell-related and agonistic behaviours towards the hybrid young, suggesting potential species recognition issues, which require further investigation. In conclusion, our findings show that hybridization has no noticeable impact on the mother–young relationship, which could partly explain the success of hybridization between the sika and red deer in the wild.
       
  • Dynamic task allocation: how and why do social insect workers take on new
           tasks'
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Nicole Leitner, Anna DornhausComplex living systems often exist in noisy environments and must have a way to respond to change. In social insects, the colony itself is a complex system composed of dozens to millions of essentially autonomous workers. Studying the behaviour of these workers in response to experimental disturbance provides insight into the mechanisms by which colonies, and complex systems in general, can achieve flexibility. Here, we explore dynamic task allocation within colonies of Temnothorax rugatulus ants by separately increasing the demand for three different types of work: nest maintenance, brood care and foraging. We investigate (1) whether colonies respond to dynamic task demand and the timeline of their responses, (2) whether the colony achieves this flexibility by recruiting new workers to these tasks or modulating individual worker effort and (3) the rules by which individual workers switch tasks. We found that T. rugatulus ants are responsive to colony perturbation, yet the means by which they achieve this flexibility are task dependent, as is the time it takes them to respond. Flexibility is achieved both by the increased effort of already active workers and the recruitment of new workers to the focal task. We suggest that newly recruited workers may come from task-specific reserve pools of unemployed workers: roaming ‘walkers’ appear to be a generalized reserve force for most tasks except for brood care, while previously inactive workers might act as a specialized reserve pool for brood care and be prompted to engage in this task when they locally encounter brood.
       
  • Mayflies avoid sweets: fish skin mucus amino sugars stimulate predator
           avoidance behaviour of Baetis larvae
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Andrea Landeira-Dabarca, Maruxa Álvarez, Barbara PeckarskyNonconsumptive effects of predators can have knock-on effects on prey fitness, life history and population dynamics. However, the origin of cues stimulating predator avoidance behaviour and the mechanisms underlying prey responses need further investigation. Previous studies revealed that nonconsumptive effects of predatory fish on Baetis mayfly larvae are mediated by water-borne chemical cues released from fish mucus. However, there are conflicting results regarding the nature of these cues and the specific role of the activity of fish mucus-dwelling bacteria in stimulating predator avoidance by prey. To address those conflicting results, we investigated whether bacteria dwelling in fish mucus and/or chemical components present in fish mucus are responsible for the predator avoidance response by Baetis mayflies to salmonids. Results of five bioassays conducted in microcosms revealed that to stimulate Baetis predator avoidance behaviour: (1) bacteria do not need to be present in salmonid mucus; (2) the saccharide fraction of the fish mucus glycosaminoglycan component, but neither the protein fraction nor the whole molecule, functions as a kairomone; (3) specific active components of the saccharide fraction are primarily amino sugars in the form of hexosamines; and (4) there is a minimum dose of mucus and specifically of hexosamine needed. Our study provides the first experimental evidence that mayfly larvae recognize fish predators via the amino sugars naturally present in fish skin mucus. These sugars are released into the water by microbially mediated breakdown of glycosaminoglycans. Further research on the responses of different invertebrate prey species to similar predator cues are needed to understand the evolutionary history of this kairomone recognition behaviour.
       
  • Presence of conspecifics reduces between-individual variation and
           increases avoidance of multiple stressors in bluegill
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Emily K. Tucker, Cory D. SuskiIndividual animals differ in their responses to external stressors, and sociability has been shown to impact whether or not an individual will avoid a stressor. However, the effect of collective group behaviour on individual avoidance in response to a stressor has not been elucidated. In this study, we sought to determine whether stressor avoidance behaviour in individuals is affected by the behaviour of a familiar shoal, and if social personality is a driver of avoidance behaviour. Bluegill, Lepomis macrochirus, were exposed to either carbon dioxide or rising temperatures in a shuttle box choice tank. All bluegill were exposed to a stressor in isolation, then their social personalities were quantified using a social network assay. Bluegill were then exposed to the same stressor in the presence of a familiar shoal, with the entire shoal being able to respond to the stressor. We found that being in a shoal significantly decreased individual avoidance thresholds to both carbon dioxide and temperature, but neither avoidance behaviour in isolation nor individual social personality type was predictive of this response. The presence of the shoal was the primary driver of the difference in avoidance behaviour when bluegill were in isolation versus when they were in groups. Potential mechanisms, both behavioural and physiological, for the relationship between group behaviour and stressor avoidance are discussed. Our results provide evidence that group movements impact individual avoidance of stressors, which may have implications for the behaviour of animals in response to decreasing habitat quality.
       
  • Dominance-related contributions to collective territory defence are
           adjusted according to the threat
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Jenny E. York, Katrina J. Wells, Andrew J. YoungAcross diverse societies, group members benefit from the cooperative maintenance of a shared territory (a public good). How such public goods are maintained has received extensive interest, yet individual contributions to cooperative territory defence remain poorly understood. Recent theory predicts that, in groups with social hierarchies, privileged individuals will contribute most to competition with rival groups as they benefit most from defence of the territory. Here, we investigated whether dominant individuals contribute more to territory defence in a group-territorial bird in which dominants monopolize within-group reproduction: the white-browed sparrow-weaver, Plocepasser mahali. Using simulated territorial intrusions, we demonstrate that dominants contributed significantly more than subordinates to territory defence. We also found that individual contributions were adjusted according to threat: males of both social classes significantly and similarly increased their contributions to defence in response to a high threat (playback of an unfamiliar pair's duet, rather than that of a neighbouring pair), which was associated with a stronger collective response by the group. Thus, while dominants contributed most as predicted by the asymmetry in benefits, subordinates did increase contributions when they were needed most (in small groups and under greater threat). Contributions by subordinates when needed most also highlights that dominants could still benefit substantially from tolerating the presence of subordinates despite their overall lower contributions. Our results show that public goods can be maintained despite unequal contributions and highlight the potential importance of context-dependent behavioural flexibility in mitigating collective action problems.
       
  • Risks and rewards: balancing costs and benefits of predator avoidance in a
           fiddler crab
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Jodie Gruber, Andrew Kahn, Patricia R.Y. BackwellThe decision to take risks in the presence of a predator involves complex trade-offs between immediate survival and future reproduction. Individuals may gain fitness advantages if they are able to optimally alter their risk-taking strategies depending on the differential costs and benefits of risky behaviours across contexts. Male fiddler crabs (Austruca mjoebergi) exhibited a higher propensity to take risks in the presence of a female compared with conspecifics that were not presented with a female during both mating and nonmating periods. Contrary to predictions, however, risk-taking behaviour did not differ between mating and nonmating periods.
       
  • Larger group sizes facilitate the emergence and spread of innovations in a
           group-living bird
    • Abstract: Publication date: December 2019Source: Animal Behaviour, Volume 158Author(s): Benjamin J. Ashton, Alex Thornton, Amanda R. RidleyThe benefits of group living have traditionally been attributed to risk dilution or the efficient exploitation of resources; individuals in social groups may therefore benefit from access to valuable information. If sociality facilitates access to information, then individuals in larger groups may be predicted to solve novel problems faster than individuals in smaller groups. Additionally, larger group sizes may facilitate the subsequent spread of innovations within animal groups, as has been proposed for human societies. We presented a novel foraging task (where a food reward could be accessed by pushing a self-shutting sliding door) to 16 groups of wild, cooperatively breeding Australian magpies, Cracticus tibicen dorsalis, ranging in size from two to 11 individuals. We found a nonlinear decline in the time taken for the innovative behaviour to emerge with increasing group size, and social information use facilitated the transmission of novel behaviour, with it spreading more quickly in larger than smaller groups. This study provides important evidence for a nonlinear relationship between group size and the emergence of innovation (and its subsequent transmission) in a wild population of animals. Further work investigating the scope and strength of group size–innovation relationships, and the mechanisms underpinning them, will help us understand the potential advantages of living in larger social groups.
       
  • Association Page
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s):
       
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    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s):
       
  • Performance on tests of cognitive ability is not repeatable across years
           in a songbird
    • Abstract: Publication date: Available online 31 October 2019Source: Animal BehaviourAuthor(s): Jill A. Soha, Susan Peters, Rindy C. Anderson, William A. Searcy, Stephen NowickiStudies of the cognitive abilities of animals aim to help us understand how they communicate, obtain resources, avoid danger and otherwise thrive in a given environment. But to what extent is cognitive ability a fixed trait in individuals' And can we answer this question by measuring performance on tests of cognitive ability' We tested the same 18 male song sparrows, Melospiza melodia, once yearly, across three consecutive years, with tests of four putative cognitive traits and a test of neophobia. We also tested 19 females twice, once in the first year and once in the third year. All birds were hand-reared and tested in the laboratory. Analyses of both data sets indicate repeatability of neophobia but not of performance on the cognitive tests. In addition, correlations among cognitive performance, neophobia and song quality that were observed in the first year were not observed in subsequent rounds of testing. These results suggest that cognitive ability is not a fixed trait in individuals, or that the tests used do not accurately measure cognitive ability, or both. Conclusions drawn from a single round of cognitive tests should therefore be interpreted with caution in this species and in any species in which repeatability has not been verified.
       
  • Playful pigs: early life play-fighting experience influences later life
           contest dynamics
    • Abstract: Publication date: Available online 25 October 2019Source: Animal BehaviourAuthor(s): Jennifer E. Weller, Irene Camerlink, Simon P. Turner, Marianne Farish, Gareth ArnottAnimal contests are costly and predicted to be won by the individual with the higher resource-holding potential (RHP). Weight is often used a proxy for RHP; however, victory does not always go to the heaviest competitor, indicating that other traits may also contribute to RHP. Here we investigated the effect of preweaning play-fighting experience on postweaning contest behaviour in the domestic pig, Sus scrofa. We predicted that individuals that played more would win contests later in life. Play-fighting experience was also predicted to influence contest escalation behaviour, on both an individual and a dyadic level. Lastly, a pre-established framework and eight contest cost measures were used to establish whether competing individuals gather/use information regarding play-fighting experience as part of an assessment strategy. Play-fighting experience was recorded for socialized and control litters before weaning and contests were staged between unfamiliar pigs of the same treatment after weaning. Controlling for competitor weight difference revealed that increased play-fighting experience was linked to contest success in females, while the opposite pattern was found in males. Play-fighting experience did not influence which individual within the dyad escalated contest behaviour, but dyads containing more experienced losers were more likely to perform a stage of nondamaging aggression. When we used skin lesions in losers as a measure of contest cost, we found evidence for the role of play-fighting experience in a novel mutual assessment strategy in socialized dyads, whereas control dyads performed opponent-only assessment. We suggest that while assessments of RHP can be made using a physical correlate of play-fighting experience (such as skillfulness), early life socialization is required for individuals to gain an understanding of their own RHP.
       
  • Presence of parents during early rearing affects offspring responses
           towards predators
    • Abstract: Publication date: Available online 24 October 2019Source: Animal BehaviourAuthor(s): Mukta Watve, Barbara TaborskySocial learning about predation threat during early ontogeny can be beneficial in developing appropriate antipredator behaviours. While such learning can be achieved through direct interactions between offspring and parents, it is unknown whether young animals can also learn appropriate responses towards different heterospecifics posing different levels of threat through inadvertent information obtained from witnessing parental interactions with these heterospecifics. In this study, we split sibling groups of the cooperatively breeding cichlid Neolamprologus pulcher and raised them with or without parents. Both rearing groups repeatedly received visual and olfactory cues from four types of fish (predators, egg predators, herbivores and conspecifics) during a 4-week experience phase. After a ‘neutral phase’ of 4 months under identical conditions and without further fish stimuli, individuals from both rearing conditions were tested for their response towards the same four stimulus species. Unlike those reared with parents, the fish reared without parents spent significantly more time in safety and were more vigilant towards the predator, whereas responses to the other three species did not differ. As during the experience phase parental responses towards the stimulus fish were unexpectedly low and indiscriminate, our results suggest that young N. pulcher reverse their innate fear of predators when observing parents being unresponsive to a threat (‘observational conditioning’). We suggest that learned reduction of fear can be a potent mechanism to prevent responding to false alarms and mitigate potentially harmful effects of chronically elevated predation stress.
       
  • Cue-based decision rules of cleaner fish in a biological market task
    • Abstract: Publication date: Available online 24 October 2019Source: Animal BehaviourAuthor(s): Sharon Wismer, Ana I. Pinto, Zegni Triki, Alexandra S. Grutter, Dominique G. Roche, Redouan BsharyTo develop an evolutionary theory of social decision making, we require an understanding of how individuals utilize environmental cues to form decision rules. We exposed ‘cleaner’ fish (bluestreak cleaner wrasse, Labroides dimidiatus) to a biological market task, where giving priority to an ephemeral (i.e. ‘visitor’ client) food plate, over a permanent (i.e. ‘resident’ client) plate, doubled the food reward. Previously published experiments revealed that adult cleaners from a complex social environment regularly solved this task and outperformed adult cleaners from a simple social environment as well as juveniles from both habitat types. In these studies, plates were differentiated by colour and/or colour pattern. However, client size is another potentially useful cue that may be used by cleaners to solve the biological market task in nature, as visitor clients are typically larger than resident clients. Here, we tested cleaners in a setting where plates differed only in size and not colour/pattern: the majority of cleaners exhibited a spontaneous preference for inspecting larger plates or were more likely to reach the task-solving criterion if the visitor plate was larger. All cleaners were able to solve the task when we incorporated both size and colour/pattern cues; however, only cleaners from the complex social environment settled on the more precise colour/pattern cue. In contrast, cleaners from the simple social environment relied on size as the primary, yet less precise, cue to solve the task. In conclusion, our results strongly suggest that intraspecific variation in the performance of cleaners in the biological market task is based on variation in the relative salience of available cues and correlates with variation in a cleaner's natural social environment. Variation in the relative salience of available cues may therefore explain a portion of the intra- and interspecific variance in cognitive performance and social behaviour documented in other animal species.
       
  • Genetic variation in sexual aggression and the factors that determine
           forced copulation success
    • Abstract: Publication date: Available online 22 October 2019Source: Animal BehaviourAuthor(s): Carling M. Baxter, Janice L. Yan, Reuven DukasSexual conflict is common in nature and sometimes results in sexual aggression. An extreme case is forced copulation, where one individual forcibly mates with another individual who resists the mating. To understand what makes some males sexually aggressive, we established an experimental system that allowed us to quantify the characteristics that contribute to males' forced copulation success. In fruit flies (Drosophila melanogaster), sexually mature females can choose to accept or reject courting males; however, males can forcibly copulate with newly eclosed, sexually immature, teneral females. We tested males from 59 genotypes and found significant genetic variation in forced copulation success, with a broad-sense heritability of 0.16. We then chose three genotypes with the lowest and three genotypes with the highest forced copulation success rates and compared the behaviour of males from these two groups. Males from genotypes with high forced copulation success were more persistent in their pursuit of teneral females and mounted them more frequently than did males from the low-success genotypes. Males of the two categories, however, were similar in their attractiveness to both teneral and sexually mature females. Our results suggest that males vary in their pursuit strategies. Some males respond to female rejection signals by giving up and searching for receptive females, while other males persist in pursuit and coercion in spite of female objection. Our work highlights the practicality of using forced copulation in fruit flies as a model for further research on the mechanisms affecting variation in sexual coercion and forced copulation success and their evolutionary consequences.
       
  • Reciprocity and rotating social advantage among females in egalitarian
           primate societies
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Kaia J. Tombak, Eva C. Wikberg, Daniel I. Rubenstein, Colin A. ChapmanInterfemale competition regimes in primate societies have been described as despotic or egalitarian based on female social behaviour. Hierarchies and nepotism are typical of despotic primates, where dominance rank and kinship are known to be strong drivers of who grooms whom and who fights with whom. However, a general theory for what structures female–female interactions in egalitarian societies remains underdeveloped. We present two nonmutually exclusive hypotheses that each propose a mechanism for levelling social advantages in a group by conferring social favour to all or most females over time: transitory states (age, residency status and reproductive state) bias social interactions and/or reciprocity governs social interactions. In this study, we (1) determined that a group of red colobus monkeys, Procolobus rufomitratus tephrosceles, in Kibale National Park, Uganda, are highly egalitarian; (2) tested our hypotheses for how egalitarianism may be maintained in this group; and (3) analysed findings across primate studies for support for either hypothesis. In red colobus, agonistic interactions were predicted by age – a transitory state – and transitory states and reciprocity predicted grooming interactions: avid groomers, older females and short-term resident females received more grooming. In addition, behavioural indicators of social status (aggression given and grooming received) were not associated with reproductive success in red colobus, as might be expected in an egalitarian group where variance in fitness should be low. Across primates, we found that transitory states commonly structure social interactions in egalitarian societies but not in despotic societies and that reciprocity is highly variable, especially among egalitarian societies. Rotating social advantage as females shift among transitory states and/or reciprocate grooming may lower interfemale skew in social benefits and potentially in lifetime reproductive success in egalitarian groups, setting them apart from despotic societies where dominance hierarchies and kinship maintain a more static and unequal distribution of social advantage.
       
  • Size matters: shiny cowbirds secure more food than host nestmates thanks
           to their larger size, not signal exaggeration
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Tatiana Bortolato, Ros Gloag, Juan C. Reboreda, Vanina D. FioriniMany hosts of obligate brood parasitic birds invest more in parasitic nestlings than they do in their own young. The shiny cowbird, Molothrus bonariensis, a generalist parasite, is fed at a higher proportion than its host nestmates when it is reared in nests of a smaller-bodied host, the house wren, Troglodytes aedon. We test two hypotheses that could account for this differential allocation of food by host parents. The signal exaggeration hypothesis states that cowbird chicks have visual and/or acoustic begging signals that elicit preferential feeding. The size-advantage hypothesis states that hosts preferentially feed large chicks and/or that larger chicks outcompete host chicks in a scramble competition for food. To gain insight into the relative importance of size versus species-specific signals on food allocation by house wrens, we performed audio and video recordings in nests with experimental broods of (1) a 2-day-old cowbird chick and a 2-day-old wren chick (different species, different size), (2) a 2-day-old cowbird chick and an 8-day-old wren chick (different species, same size) and (3) a 2-day-old house wren and an 8-day-old house wren (same species, different size). When cowbirds shared the nest with a same-size wren chick, both chicks received food in equal proportion. In contrast, larger chicks (both cowbirds and wrens) paired with small wren nestmates always received a higher food share. Cowbird begging behaviour and call traits differed from house wrens, but these differences did not always coincide with increased food. We conclude that, at least when cowbird nestlings are young (2 days old), their relatively large size accounts for the larger share of food they receive from house wren hosts, rather than some quality of their begging signal.
       
  • Behavioural repeatability is affected by early developmental conditions in
           a butterfly
    • Abstract: Publication date: Available online 16 October 2019Source: Animal BehaviourAuthor(s): Aurélien Kaiser, Thomas Merckx, Hans Van DyckFor developing organisms, early environmental conditions are critical as they provide cues about their environment and are thus helpful to make decisions for the short and long term. As such, the early environment is known to affect several phenotypic traits, and these can persist after developmental growth. However, the role of these early environmental conditions in shaping personality traits remains largely unknown. Here, we used a reciprocal transplant experiment to explore the effect of landscape of origin versus landscape of development on boldness and activity in a butterfly, Pararge aegeria. Larvae of woodland, agricultural and urban population origins were reared in situ in their landscape of origin or under the two alternative environmental conditions. We then repeatedly quantified boldness and activity in the F1 adults under laboratory conditions. While the landscape of development appeared to have no effect on mean trait values, it affected trait repeatability through changes in among-individual variation. Additionally, males of agricultural origin had higher mean boldness scores than woodland and urban origin males. Also, average boldness declined with testing sequence in individuals of woodland origin, but not in agricultural and urban origin individuals. Overall, our results suggest that (1) conspecifics originating from distinct habitat types differ in some aspects of boldness, and (2) early developmental conditions can affect behavioural consistency without changing mean behavioural phenotypes.
       
  • Detecting social (in)stability in primates from their temporal co-presence
           network
    • Abstract: Publication date: Available online 15 October 2019Source: Animal BehaviourAuthor(s): Valeria Gelardi, Joël Fagot, Alain Barrat, Nicolas ClaidièreThe stability of social relationships is important to animals living in groups, and social network analysis provides a powerful tool to help characterize and understand their (in)stability and the consequences at the group level. However, the use of dynamic social networks is still limited in this context because it requires long-term social data and new analytical tools. Here, we studied the dynamic evolution of a group of 29 Guinea baboons, Papio papio, using a data set of automatically collected cognitive tests comprising more than 16 million records collected over 3 years. We first built a monthly aggregated temporal network describing the baboon's co-presence in the cognitive testing booths. We then used a null model, considering the heterogeneity in the baboons' activity, to define both positive (association) and negative (avoidance) monthly networks. We tested social balance theory by combining these positive and negative social networks. The results showed that the networks were structurally balanced and that newly created edges also tended to preserve social balance. We then investigated several network metrics to gain insights into the individual level and group level social networks' long-term temporal evolution. Interestingly, a measure of similarity between successive monthly networks was able to pinpoint periods of stability and instability and to show how some baboons' ego-networks remained stable while others changed radically. Our study confirms the prediction of social balance theory but also shows that large fluctuations in the numbers of triads may limit its applicability to study the dynamic evolution of animal social networks. In contrast, the use of the similarity measure proved to be very versatile and sensitive in detecting relationships' (in)stabilities at different levels. The changes we identified can be linked, at least in some cases, to females changing primary male, as observed in the wild.
       
  • Dispersal decisions and personality in a freshwater fish
    • Abstract: Publication date: Available online 15 October 2019Source: Animal BehaviourAuthor(s): William D. Coates, Robin Hale, John R. MorrongielloHistorically, the differences in dispersal behaviour between individuals within a species has largely been ignored. Instead, we tend to assume all individuals within a population express similar phenotypes. However, evidence is growing for the importance of intraspecific variability in dispersal propensity and how this variability may influence population dynamics, as well as the role of environmental context in driving this behaviour. Individuals that are more likely to disperse can have other traits, such as being bolder or more aggressive, that collectively form behavioural syndromes. We tested for a behavioural syndrome in carp gudgeons (Hypseleotris spp.) species' complex, a type of small fish found in intermittent streams in southeastern Australia. Intermittent streams are an environment where selection may favour the evolution of different dispersal phenotypes, given the variable and unpredictable nature of flows. During dry periods, fish become isolated in refuge pools that vary in quality and persistence, and then can disperse when flow resumes. Dispersal can have costs (e.g. the risk of not finding another habitat) but also benefits (e.g. opportunity to find better habitat), meaning that different strategies (i.e. dispersing versus staying) may both be advantageous and thus evolve. Through a series of experiments that assessed these fish's latency to emergence into a novel environment and tendency to shoal, as well as movement behaviour in artificial streams, we found that (1) flow is not likely to be a movement cue, and (2) boldness, sociability and dispersal distance were repeatable, consistent with the notion that carp gudgeons exhibit personalities. To our knowledge, this is the first demonstration of a behavioural syndrome in a freshwater fish that inhabits intermittent streams. This finding contributes to our understanding of how carp gudgeons move through intermittent streams and the potential dynamics that allow these fish to persist in such harsh, hydrologically variable habitats.
       
  • Camera traps provide a robust alternative to direct observations for
           constructing social networks of wild chimpanzees
    • Abstract: Publication date: Available online 15 October 2019Source: Animal BehaviourAuthor(s): Maureen S. McCarthy, Marie-Lyne Després-Einspenner, Damien R. Farine, Liran Samuni, Samuel Angedakin, Mimi Arandjelovic, Christophe Boesch, Paula Dieguez, Kristin Havercamp, Alex Knight, Kevin E. Langergraber, Roman M. Wittig, Hjalmar S. KühlSocial network analysis provides valuable opportunities to quantify the nature of social relationships in animal societies including aspects of group structure, dynamics and behaviour transmission. Remote monitoring approaches such as camera trapping offer rich data sets from groups and species that are difficult to observe, yet the robustness of these data for constructing social networks remains unexplored. Here we compared networks of party association based on camera traps with those based on direct observations over the same 9-month sampling period in a group of habituated western chimpanzees, Pan troglodytes verus. Networks based on camera traps and direct observations were both stable with sufficient sampling, and had very similar structures, patterns of sex assortment and individual network positions. However, camera trap data led to lower estimates of group density and dyadic association strengths, and slightly higher modularity, illustrating the limitations raised by differences in data collection methods for network comparisons. We then constructed a social network using camera trap data from unhabituated eastern chimpanzees, P.t. schweinfurthii, demonstrating the feasibility of this approach in the absence of extensive prior knowledge of the study subjects. Further, differences between the eastern and western chimpanzee social networks followed expected patterns based on recognized social differences, illustrating the promise of this approach for detecting within-species social variation. Although long-term behavioural observations will continue to provide rich data for many species, camera traps offer a powerful alternative to gain information on social group dynamics in elusive or unhabituated animals, as well as to conduct systematic multisite comparative studies.
       
  • High-stress rearing temperature in Acipenser fulvescens affects
           physiology, behaviour and predation rates
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Lydia Wassink, Ugo Bussy, Weiming Li, Kim ScribnerEarly life stress can lead to long-term behavioural and physiological phenotypic alterations that impact fitness. Understanding effects of environmental stressors on wildlife is important to predict individual and population-level responses to stressors associated with climate change. Lake sturgeon, Acipenser fulvescens, are a regionally threatened fish species that experience high predation rates during larval stages. To investigate effects of a high temperature stressor, we exposed lake sturgeon eggs from four families to 10 °C (low-stress) or 18 °C (high-stress) rearing temperatures. At egg, free embryo and larval stages, we quantified stress levels for individuals from each treatment using whole-body cortisol analysis at baseline and after an acute stressor. At the larval stage, we videorecorded behaviour trials to quantify swimming activity, and we conducted predation trials to quantify survival outcomes for individuals from high-stress and low-stress temperature treatments. Free embryos reared at 18 °C had a significantly smaller cortisol response after exposure to an acute stressor, indicating that chronic high temperature stress may reduce stress reactivity in lake sturgeon. In addition, larvae reared at 18 °C had significantly higher activity levels during behaviour trials and significantly higher survival rates when exposed to crayfish predation, indicating that behavioural alterations induced by early life stress may be adaptive in high-stress contexts such as predation. These findings illustrate the need to experimentally evaluate fitness effects of stressors within ecologically relevant contexts in order to predict population- and community-level outcomes of climate change.
       
  • Pre-existing differences in putative fertility signals give workers the
           upper hand in ant reproductive hierarchies
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Romain Honorio, Nicolas Châline, Stéphane ChameronIn social groups, competition often gives rise to conflicts, which are regulated through a variety of mechanisms. In several social insect species, the conflict for male production that takes place between workers after queen loss, is regulated through the establishment of a reproductive hierarchy. A recent study of Neoponera apicalis showed that workers differ in their fertility levels in the presence of the queen and proposed that such idiosyncratic differences might influence access to the top of the hierarchy after queen loss. In this study, we therefore sought to characterize the influence of the initial heterogeneity in ovarian development and its chemical and behavioural correlates on the establishment of reproductive hierarchies among orphaned workers, which can only produce males. We monitored the chemical profile before and after hierarchy establishment in four groups of orphaned workers of N. apicalis morph 6. The analysis of the cuticular profiles showed that tricosane (n-C23) was highly correlated with ovarian development and could consequently act as a fertility signal in this ant. The relative amount of tricosane on the cuticle, both before and after the establishment of the hierarchy, was also correlated with the rank achieved within the hierarchy and with the expression of agonistic behaviours. Thus, our study experimentally shows that idiosyncratic differences in a putative fertility signal (and therefore presumably in ovarian activity) between workers in the queen's presence reliably predict the outcome of reproductive conflict after queen loss. We propose that this signal (together with an increased agonistic motivation of the more fertile workers) could play a major role in the regulation of dominance/submission behaviours, enabling the most fertile individuals to rapidly access top ranks and monopolize reproduction, thereby maximizing the global reproductive success of all colony workers while minimizing the costs associated with the expression of agonistic behaviour.
       
  • Individual differences in anxiety are related to differences in learning
           performance and cognitive style
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Julie Gibelli, Nadia Aubin-Horth, Frédérique DuboisIndividuals of the same population differ in their cognitive abilities, that is, in their capacity to acquire, process, store and act on information from the environment. The question of whether individuals with different personality types differ in their learning performances has been commonly addressed but has yielded mixed results. We propose that methodological differences among studies might have contributed to these contrasting results. Notably, the strength and direction of the association between personality and learning might be affected by which personality traits are considered and how they are measured. To test this hypothesis, we conducted an experiment with sailfin mollies, Poecilia latipinna. We assessed three personality traits that are likely to affect individuals’ performance by influencing either their willingness to encounter the new situation (i.e. exploration and neophobia) or their susceptibility or emotional reactivity to stressful situations (i.e. anxiety). Then, we scored their performance in two learning tasks (i.e. discrimination and spatial reversal learning) after they had been extensively familiarized with the learning device and hence were all willing to encounter the task. We found that only anxiety had a significant effect on learning performance, with less anxious fish performing better in the discrimination learning task but worse in the spatial reversal task than highly anxious ones. Thus, our findings confirm a link between personality and cognition and are consistent with the idea that learning requires different steps that are each associated with different personality traits. Furthermore, highly anxious fish, on average, needed more trials to learn an association but some of them (with presumably high energetic requirements) consistently took more time before making a choice and had higher performance than their counterparts that made faster decisions.
       
  • Behaviour of an alpine range-restricted species is described by
           interactions between microsite use and temperature
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Krista N. Oswald, Ben Smit, Alan T.K. Lee, Susan J. CunninghamClimate change predictions include increased mean temperatures and increased frequency of heatwaves. Short-term responses to high air temperatures can allow animals to conserve water while maintaining a safe body temperature. For birds, cooling is often through evaporative water loss, which can be physiologically costly. Microsite use is an effective means of conserving water via reducing environmental heat load, so long as there are no negative trade-offs with other necessary functions, such as foraging. We examined behavioural responses to temperature in Cape rockjumpers, Chaetops frenatus (hereafter: ‘rockjumper’), an alpine specialist bird. We hypothesized that rockjumper behaviours would be temperature and microsite dependent. We collected data on rockjumper microsite use (sun, rock shade), behaviour (activity, foraging, preening, panting) and temperature (air, environmental). Rockjumpers made increased use of rock shade as air temperature increased. However, birds in rock shade foraged less. Depending on where their main food source is located, this suggests that when foraging demands are high, birds may need to remain in the sun despite risks of high thermal load, or else may suffer costs of lost foraging opportunities when using shade. The relationship between air temperature and heat dissipation behaviour (panting) was also mediated by microsite: birds showed significant increases in panting with increasing air temperature only when in the sun. The lack of increase in panting for birds in rock shade suggests that shade seeking may buffer physiological thermoregulatory costs (i.e. water expenditure). Individuals may therefore be able to mitigate some potential negative effects of high temperatures by making use of cooler microsites, although this could come at a cost to foraging.
       
  • Speed consensus and the ‘Goldilocks principle’ in flocking birds
           (Columba livia)
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Daniel W.E. Sankey, Emily L.C. Shepard, Dora Biro, Steven J. PortugalThe evolution of group living transformed the history of animal life on earth, yielding substantial selective benefits. Yet, without overcoming fundamental challenges such as how to coordinate movements with conspecifics, animals cannot maintain cohesion, and coordination is thus a prerequisite for the evolution of sociality in nonstationary animals. Although it has been considered that animal groups must coordinate the timing and direction of movements, coordinating speed is also essential to prevent the group from splitting. We investigated speed consensus in homing pigeon, Columba livia, flocks using high-resolution GPS. Despite observable differences in average solo speed (which was positively correlated with bird mass) compromises of up to 6% from the preferred solo speed were made to reach consensus in flocks. These results match theory which suggests that groups fly at an intermediate of solo speeds, which suggests speed averaging. By virtue of minimizing extreme compromises, speed averaging can maximize selective benefits across the group, suggesting shared consensus for group speed could be ubiquitous across taxa. Nevertheless, despite group-wide advantages, contemporary flight models have suggested unequal energetic costs in favour of individuals with intermediate body mass/preferred speed (hence the ‘Goldilocks principle’).
       
  • Seasonal variation and stability across years in a social network of wild
           giraffe
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Steffen G. Prehn, Barbara E. Laesser, Cecilie G. Clausen, Kristina Jønck, Torben Dabelsteen, Josefine B. BraskAnimal social networks have been studied intensively in the last decade, but there are relatively few studies of their temporal stability and variation, including the influence of season. We quantified the social network structure across time of a population of wild giraffe, Giraffa camelopardalis, in South Africa. Our aim was to investigate differences between dry and wet seasons and stability across years of giraffe social structure. We found temporal stability in terms of association patterns across years, including between seasons, for the population as a whole and for each sex separately. A comparison of the mean social connectedness of individuals between the wet and dry seasons revealed significant differences, with individuals having more social ties and being stronger socially connected in the wet season. Further analyses revealed that this result stemmed from differences in female–female and intersexual associations, whereas there was no evidence for social connectedness among males being affected by season. In summary, while the extent of social connectedness differed between seasons, the overall social connection pattern of the population was stable over time. This study underlines the importance of long-term surveys of wild animals and their social networks and demonstrates that animals can adapt their social behaviour to ecological changes while simultaneously maintaining a stable social structure.
       
  • Editors' Acknowledgments
    • Abstract: Publication date: Available online 29 September 2019Source: Animal BehaviourAuthor(s):
       
  • Contest interactions and outcomes: relative body size and aggression
           independently predict contest status
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Lisa D. Mitchem, Reena Debray, Vincent A. Formica, Edmund D. BrodieIn species with pronounced male armaments, body and weapon size often determine success in agonistic interactions. However, the behavioural components of interactions also play a significant role in determining outcomes and individuals that win agonistic interactions may not be the ones that start contests. In this study, we used dyadic, intrasexual assays to characterize agonistic behaviours and determine whether body size and/or the propensity to start interactions influences contest outcome. We characterized agonistic interactions from start to end in the sexually dimorphic forked fungus beetle, Bolitotherus cornutus. Males of the species are known to use their thoracic horns in intrasexual combat, but other aspects of male–male behaviour are undescribed. We created an ethogram that described transitions between behaviours and categorized actions as aggressive, nonaggressive and mounting. Individual aggressive and nonaggressive behaviours were highly repeatable between trials while mounting behaviours were not repeatable. The initiation of nonaggressive and mounting behaviours was not predictive of contest outcome. Relative body size and absolute aggression independently predicted contest outcome. Our results indicate that traits important for establishing contest outcome are not always correlated. Considering either aggression or body size alone may be misleading when determining competitor abilities.
       
  • Neuropeptide manipulation has behavioural and cascading fitness
           consequences in wild-living fish
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Kelly A. Stiver, Susan E. Marsh-Rollo, Suzanne H. AlonzoDue to the difficulty of simultaneously assessing variation in individual physiology, behaviour and fitness, we often know little about the mechanistic basis of life-history trade-offs and fitness variation. It is similarly challenging to examine how physiological variation in one individual has cascading fitness consequences for others in the social environment. Using a wild-living fish (ocellated wrasse, Symphodus ocellatus), we manipulated a neuropeptide pathway associated with courtship, aggression and parental care in vertebrates (arginine vasotocin, AVT) and directly examined the behavioural and fitness consequences. Nesting males injected with the AVT antagonist increased their paternal care, resulting in increased hatching of offspring and increased reproductive success of all individuals that mated at his nest. By directly examining physiology, behaviour and reproductive success, we revealed how a small change in individual physiology has clear and direct fitness consequences for multiple individuals.
       
  • Male responses suggest both evolutionary conservation and rapid change in
           chemical cues of female widow spiders
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Luciana Baruffaldi, Humera Siddiqui, Athithya Thambiappah, Maydianne C.B. AndradeUnderstanding patterns of diversity in sexual signals can give insight into processes initiating, mediating or following from species diversification. Here we focus on female sex pheromones, which are widespread among animals, where some taxa show phylogenetic patterns of variation, but for others, ecological factors better explain pheromone diversity. Causes of differences in these patterns are unclear, and general insights require studying a broader range of taxa. Here we examined variation in the responses of male redback spiders, Latrodectus hasselti, to sex pheromones produced by three allopatric female congeners with different degrees of phylogenetic relatedness (from the same clade: Latrodectus mirabilis, Latrodectus hesperus; and from a different clade: Latrodectus geometricus) to infer pheromone divergence. We examined variation in male responses to conspecific and heterospecific females’ airborne and contact pheromones, which attract males and elicit courtship behaviour, respectively. We measured male courtship responses to extracted contact pheromones in isolation and male preferences in response to airborne pheromones and combined cues (pheromones, silk) in a two-choice maze. Male responses to airborne chemicals, contact chemicals and combined cues suggested variation in species specificity, with L. hasselti males showing strong discrimination against airborne pheromones of L. hesperus females (same clade), moderate evidence for discrimination based on contact cues of L. geometricus, but only when multiple sources of information were available (different clade), and no discrimination of L. mirabilis females (same clade) relative to conspecifics, regardless of the types of information available. Thus, male responses were not consistent with a phylogenetic pattern. Moreover, airborne pheromones can apparently diverge relatively rapidly, but airborne and contact pheromones may remain similar across long evolutionary timescales. We propose that differential responses to L. hesperus may arise from selection for population-level pheromone divergence within that species and that, in general, pheromones and male responses may be evolutionarily conserved across Latrodectus.
       
  • Natural sounds alter California ground squirrel, Otospermophilus beecheyi,
           foraging, vigilance and movement behaviours
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): My-Lan T. Le, Christopher M. Garvin, Jesse R. Barber, Clinton D. FrancisMany animals rely on the acoustic environment for functions spanning mate attraction, navigation and predator and prey detection. Growing evidence focused on human-altered acoustic environments suggests that anthropogenic noise can strongly interfere with the reception of biologically relevant sounds, causing a variety of behavioural changes in response to the evolutionarily novel acoustic conditions created by humans. However, little is known about how background natural sounds, such as river noise and biotic choruses, alter behaviour. Using field-placed playback of predominantly low-frequency whitewater river rapids, higher-frequency cicada choruses (∼7.0–15.0 kHz) or a silent control, we sought to determine whether background natural sounds influence vigilance and foraging behaviour in the California ground squirrel. We found that California ground squirrels exposed to low-frequency river sounds increased vigilance and decreased foraging and movement relative to ambient acoustic conditions during control trials and, to a lesser extent, acoustic conditions imposed by the cicada chorus playback. Additionally, vigilance increased with sound level regardless of whether the playback stimulus was the low-frequency river noise or the high-frequency cicada chorus. However, background sound level interacted with group size, such that increased sound levels were associated with a strong increase in vigilance in small groups but not in larger groups. To our knowledge these results are the first to demonstrate that the spectral content and amplitude of natural sounds can influence vigilance and movement behaviours. Yet our results match those from recent studies reporting increased vigilance in response to low-frequency anthropogenic noise, suggesting that many observed responses to anthropogenic sounds may be those that animals have used to cope with variable sound levels from natural sources throughout their evolutionary history. Determining how natural sounds influence other key behaviours is ripe for future studies and will likely prove useful for predicting behavioural adjustments in response to an increasingly noisy world.
       
  • Subspecies discrimination on the basis of acoustic signals: a playback
           experiment in a Neotropical songbird
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Alana D. Demko, J. Roberto Sosa-López, Daniel J. MennillWhen animal mating signals diverge between populations, reproductive isolation and speciation may occur. Variation in animals' responses to these signals may reveal whether differences in perception contribute to behavioural differences between populations. We tested whether signal divergence influences receiver responses to playback in the rufous-capped warbler, Basileuterus rufifrons, a Neotropical resident songbird with a contact zone between two divergent subspecies, B. r. delattrii and B. r. rufifrons, in southern Mexico. Studying nearby populations of birds living in allopatry and sympatry, we presented warblers with playback-simulated territorial male rivals of each subspecies. In sympatry, both delattrii and rufifrons responded more strongly to songs of their own subspecies than to songs of the other subspecies, whereas in allopatry, delattrii responded strongly to songs of both subspecies, suggesting possible reproductive character displacement. Our research demonstrates that sympatric delattrii and rufifrons discriminate between each other's songs, suggesting that song is a premating isolating barrier between these divergent subspecies. This study adds to the growing literature on receiver response to vocal signal divergence in closely related sympatric and allopatric animal populations.
       
  • Female guppies increase their propensity for polyandry as an inbreeding
           avoidance strategy
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Elizabeth M. Speechley, Clelia Gasparini, Jonathan P. EvansMating with close relatives often causes a decline in offspring fitness, termed inbreeding depression. Consequently, pre- and postcopulatory inbreeding avoidance mechanisms are likely to evolve, especially in females due to their relatively high levels of reproductive investment. If precopulatory inbreeding avoidance mechanisms are absent or unreliable, females may exploit postcopulatory sexually selected inbreeding avoidance mechanisms by mating with multiple males (polyandry). Despite this expectation, few studies have tested whether females alter their propensity to mate multiply in an inbreeding avoidance context. Here, we tested whether the perceived risk of inbreeding promotes polyandrous behaviour in guppies, Poecilia reticulata, a species susceptible to inbreeding depression. Virgin females were assigned to either a sibling or nonsibling mating and subsequently presented with three unrelated males simultaneously. Consistent with previous studies, we found that females did not discriminate between initially encountered males based on relatedness. However, females increased their propensity to mate multiply after mating with a brother. Subsequent paternity tests were performed to determine whether polyandry minimizes inbreeding through a dilution effect (i.e. greater number of sires in the related treatment) or through postcopulatory biasing mechanisms (i.e. greater paternity skew towards unrelated males). Surprisingly, our results supported neither scenario; we detected no significant difference in paternity skew or the number of sires between treatments. Overall, our study provides a rare example of females responding to an increased risk of inbreeding by increasing their propensity to remate, but the postcopulatory processes arising from this behaviour, along with the mechanisms underlying kin recognition, await further investigation.
       
  • Niko Tinbergen and questions of instinct
    • Abstract: Publication date: Available online 24 September 2019Source: Animal BehaviourAuthor(s): Colin BeerNiko Tinbergen characterized ethology as ‘the biological study of behaviour’ involving four kinds of question: causation, ontogeny, adaptive function and phyletic evolution (Tinbergen, 1963; Zeitschrift für Tierpsychologie, 20, 410–433). He said the science should give equal attention to each and to their integration. This division was prefigured in his book The study of instinct (Tinbergen, 1951; Oxford University Press). The book offered a conception of instinct as a built-in motivational system analogous to a hydraulic mechanism. The assumption of innateness and the lack of physiological credibility of the instinct model met with adverse criticism, which Tinbergen conceded to a large extent. His later work concentrated on functional issues, which anticipated the direction dominating subsequent ethological studies. Nevertheless Tinbergen's four questions, and his insistence that they be given equal attention continue to present an agenda for ethological aspiration.
       
  • Mate choice in naturally inbred spiders: testing the role of relatedness
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Cristina Tuni, Laia Mestre, Reut Berger-Tal, Yael Lubin, Trine BildeMate preference based on relatedness may evolve in response to costs and benefits of inbreeding avoidance. Whereas mating with closely related individuals can have negative fitness consequences due to inbreeding depression, it may simultaneously be favoured by inclusive fitness benefits. Variation in the fitness payoff shaped by benefits of inbreeding may even lead to preference for mating with kin. We investigated this hypothesis in the social spider Stegodyphus dumicola, a cooperative species in which reproduction occurs among siblings within the group, premating dispersal is lacking and infrequent encounters with unrelated individuals result in homozygous genetic lineages. We tested whether female mate choice is influenced by male relatedness by pairing females with males that differ in the degree of genetic relatedness, namely nest members, non-nest members from the same population and non-nest members from allopatric populations. We recorded premating (male rejections, latency to mating) and mating (copulation duration and interruptions) behaviours. Females showed no preference for partners on the basis of their relatedness during the premating phase, as frequencies of rejections and successful matings did not differ markedly in encounters with nest and non-nest members. This suggests that selection on discriminatory mechanisms may be weakened or lost in species with inbreeding tolerance and in which relatedness between interacting individuals is very high and variance in relatedness extremely low. Unrelated males from the geographically distant population experienced longer copulations than males from the same population. We interpret this finding as depicting a possible scenario of a between-population reproductive barrier or functional incompatibility, which may be the mechanism causing lower fitness in between-population crosses previously documented in these populations.
       
  • Relationships between male giraffes’ colour, age and sociability
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Madelaine P. Castles, Rachel Brand, Alecia J. Carter, Martine Maron, Kerryn D. Carter, Anne W. GoldizenIn species in which males signal competitive ability through secondary sexual traits, males with different levels of trait expression may adopt different reproductive tactics to maximize their reproductive success. In fission–fusion social systems, the most dominant males often roam widely in search of females in oestrus, and thus exhibit different patterns of sociability from subordinate males that utilize alternative reproductive tactics. Giraffes, Giraffa camelopardalis, are rare among mammals in that they are sexually dimorphic in colour, and colour is hypothesized to function as a signal of males’ social status by displaying their competitive ability. Here we analysed the coat colour and sociability of 66 wild male giraffes over 12 years at Etosha National Park in Namibia to test two premises underlying this hypothesis. First, we found that males did not all darken at the same rate or to the same degree, and colour variation increased with age. This suggests that colour is not solely an age-based trait but could be a secondary sexual trait. We then showed a distinct difference in the sociability of both young and pale males compared to darker males. Both younger and paler old males tended to be more gregarious while darker males were more solitary. This is consistent with a system where darker, more dominant males roam looking for females in oestrus. Younger or subordinate males may delay roaming or use an alternative tactic, such as remaining in groups with females to gain copulations when a more dominant male is not present. Our results are consistent with the hypothesis that male giraffe coat colour functions as a signal of social status through competitive ability, but deeper study into movement patterns and the costs and benefits associated with darker colours is required.
       
  • Testing the role of same-sex sexual behaviour in the evolution of
           alternative male reproductive phenotypes
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Jack G. Rayner, Nathan W. BaileyMale same-sex sexual behaviour (SSB), where males court or attempt to mate with other males, is common among animal taxa. Recent studies have examined its fitness costs and benefits in attempts to understand its evolutionary maintenance, but the evolutionary consequences of SSB are less commonly considered. One potential impact of SSB might be to facilitate the evolution of traits associated with less sexually dimorphic males, such as alternative reproductive tactics, by diverting costly aggression from other males. To test this, we capitalized on the recent rapid spread of a silent male morph of the field cricket, Teleogryllus oceanicus, which is unable to produce characteristic male acoustic signals, benefits from satellite mating behaviour and has feminized appearance and cuticular hydrocarbon profiles. We tested the prediction that interactions involving these nonsignalling, less sexually dimorphic male morphs would show heightened rates of SSB, which could reduce the strength of male–male competition and permit greater access to females. We found no evidence that SSB was more common in trials involving silent males. Instead, SSB was predicted by courtship of females presented during a pretrial treatment. Our results provide evidence supporting the view that SSB represents a spillover of sexually selected courtship behaviour in a nonadaptive context, but do not support a strong role for SSB in the evolution of less ornamented males in this system.
       
  • Genetic variation in maternal yolk testosterone allocation predicts female
           mating decisions in Japanese quail
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Daniela Ledecka, Michal Zeman, Monika OkuliarovaMaternal reproductive effort can be adjusted through the transfer of hormones into the eggs, where they influence embryo development, mediating short- and long-term maternal effects on offspring phenotype. While studies usually explore how females can increase their reproductive success through an allocation of yolk testosterone (T) under external environmental variability, it is less clear whether intrinsically driven interfemale differences in yolk T deposition may themselves predict female reproductive decisions. In our study, we used Japanese quail, Coturnix japonica, lines divergently selected for high (HET) and low (LET) egg T concentrations to examine whether this genetic variation in yolk T levels is linked to female mating decisions. First, we analysed line differences in male-typical reproductive behaviour and how this behavioural response is affected by female line identity. Males were tested with females from the same (match pairs) and opposite (cross pairs) lines. Next, female mate preferences were evaluated in a two-choice test in which females were allowed to choose between males from the same and opposite lines. We found no line differences in male copulatory behaviour. Interestingly, a shorter latency to copulate and a higher number of copulations were recorded in LET males when they were mated with HET than LET females. No differences between match and cross pairs were found in HET males. In the two-choice test, LET females displayed a preference for males from the same over the opposite line, but HET females did not discriminate between LET and HET males. Collectively, these results demonstrate that genetically high yolk T deposition is related to higher receptivity and reduced choosiness in female mate preferences in Japanese quail. Moreover, our results indicate an important link between maternal investment, reproductive physiology and female mating decisions, pointing out evolutionary implications and a role of variation in female mate choice in sexual selection.
       
  • Erratum to ‘Chimpanzees, but not bonobos, attend more to infant than
           adult conspecifics’ [Animal Behaviour 154 (2019) 171–181]
    • Abstract: Publication date: November 2019Source: Animal Behaviour, Volume 157Author(s): Yuri Kawaguchi, Fumihiro Kano, Masaki Tomonaga
       
 
 
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