Ethology最新文献

While it is well established that apes invent or individually learn new gestures, cases of development and use of novel gestures in monkeys are more rarely described. We report a case of a novel, idiosyncratic gesture in a Barbary macaque (Macaca sylvanus) at ‘La Forêt des Singes’, Rocamadour, France. One adult male, Jomanix, was observed hand-clapping. To our knowledge, hand-clapping has never been described before in this species. To hand-clap, the male briefly shifted his weight onto his legs, lifted his upper body, and clapped both hands together. We recorded 30 instances of hand-clapping. Twenty-five of these hand-claps occurred in combination with other agonistic signals, such as lunges and open mouth threats. Recipients either responded with counter-aggression (N = 9) or a submissive response (N = 16). In five of the 30 events, the context was unclear. These observations suggest that the gesture constitutes an agonistic signal. According to the staff at ‘La Forêt des Singes’, the hand-clapping may have been copied from staff members who occasionally hand-clap to shoo the animals away from areas where they were not supposed to be but that notion remains speculative. In the meantime, another subject from the same group reportedly started to hand-clap but the subject had passed away before we could document the behaviour. The observations show that Jomanix can flexibly combine a novel gesture with other established communicative signals. The hand-clap is goal-directed and fulfils the criteria for first-order intentional communication. This case, as well as anecdotal reports from a Tonkean macaque (Macaca tonkeana) hand-clapping to get attention, reveals greater flexibility in the gestural communication of this genus than previously assumed but also underscores that social learning of the production of communicative gestures occurs rarely in this taxon.

In the Indo-West Pacific biogeographical region, a suite of shorebirds searches for crabs as food. While the majority of these shorebirds hunt on burrowing crabs, the endemic crab plover Dromas ardeola additionally feeds on swimming crabs with “fast and powerful claws”. Here, we examined the trade-off made by crab plovers between foraging for swimming crabs and burrowing crabs on the intertidal mudflats of Barr Al Hikman in the Sultanate of Oman during four winters (2012–2015). Foraging on burrowing crabs requires waiting for the occupant to emerge, whereas foraging on swimming crabs involves searching and extensive handling. We found that crab plovers strongly preferred swimming crabs. In fact, diet composition was exclusively a function of the densities of swimming crabs, that is, crab plovers stopped waiting for burrowing crabs above threshold densities of swimming crabs even if burrowing crabs were abundant. Using a two-prey functional response model, we could explain diet composition from an energy-maximization perspective, but only if waiting time was added as an identification phase independent of prey densities. This suggests that crab plovers exhibit selective attention and can only wait for a limited number of burrowing crabs at a time. We conclude that the preference for swimming crabs emerges from both the efficient handling of swimming crabs by the crab plover and the long hiding times of the burrowing crabs. Undoubtedly, it is the crab plovers' specialized bill which makes handling of swimming crabs profitable. We speculate that this bill uniquely evolved in the “escalated” environment of the Indo-West Pacific.

Predation risk exerts significant pressure on the survival of prey species and has many indirect impacts on their habitat use, energy allocation, and community dynamics. Prey must consistently assess their surroundings by using multiple information sources to monitor predation risk and respond accordingly. In aquatic environments, chemical signals (i.e., alarm cues, disturbance cues, and predator odors) play a crucial role in informing prey of predation risk. Here, we systematically assess the impact of two non-lethal cues, disturbance cue and predator odor, on four aspects of prey fish behavior using the common blackchin shiner (Miniellus heterodon), a possible surrogate species for the Threatened pugnose shiner (Miniellus anogenus). In experiment 1, we found that conspecific disturbance cue elicited an increase in activity relative to the controls. However, there were no changes in area use, shoaling, or shelter use. In experiment 2, we found that predator odor elicited increased shelter use in blackchin shiner, consistent with an antipredator strategy, but no changes in activity, area use, or shoaling. Our two experiments suggest that disturbance cues and predator odors elicit different behavioral responses in blackchin shiner, perhaps since sources of risk information vary in their urgency and reliability. These results aimed to provide the baseline for future work on pugnose shiner, and demonstrate the value of using non-lethal chemical cues, with standardized methods, to study antipredator behavior in threatened species.

The expression of melanic or black coloration is ubiquitous and has significant behavioral and ecological relevance. Although black coloration is common, melanic morphs within populations are often considered rare. The mechanism for the maintenance of rare melanic morphs is often associated with differences in morph behavior, predator preference, or the interaction of both. Mechanistically, the genetic loci associated with black coloration in rare morphs can also influence behaviors, and these pleiotropic effects may provide some benefit to black morphs. We predicted that different mating behaviors, antipredator responses, and stress response, as well as predator preference influenced the maintenance of a rare black morph in freshwater Eastern mosquitofish. We created predator and control treatments to measure differences in melanic and silver mosquitofish behavior and cortisol levels. We also measured predator approach and attack of melanic and silver morphs. Overall, melanic morphs exhibited a higher number of mating behaviors compared to silver morphs and returned to mating attempts quicker than silver morphs after predator exposure. Melanic males also exhibited higher baseline cortisol levels, but silver males produced more cortisol after predator exposures compared to melanic males. These specific responses may provide the mechanism by which melanic males continue to persist in populations where they are rare.

Pair bonds are a hallmark of many monogamous species, yet in the monogamous California mouse (Peromyscus californicus) pair-bond formation is poorly understood. While pair bonds are often assumed to be present after a week of cohabitation, when they actually form in this species is debated. To characterize pair bond latency in California mice, we conducted three-chamber partner preference tests for both males and females following 1, 3, 5, or 7 days of cohabitation. Since copulation may contribute to pair-bond formation, animals were paired when females were in estrus and were assessed continuously throughout the cohabitation period for copulatory behavior. We found evidence of pair bonds after 24 h of cohabitation for both sexes with no significant changes in partner preference behaviors across cohabitation periods. Focal animals spent more time in the partner's chamber, were more affiliative toward the partner than the stranger and displayed more aggressive behavior toward the stranger. Affiliative behaviors were consistent between the sexes, while males attacked the stranger more frequently and for longer durations than females. Pairs that copulated prior to partner-preference testing spent more time in the partner's chamber and more time huddling, licking, and grooming their mate than those that did not copulate. We conclude that although copulation may not be necessary for pair-bond formation, sexual receptivity at time of pairing is important for the development of these social relationships and that copulation may serve to enhance pair bonds in California mice.

Animals move in three spatial dimensions, but many animal movement tools have only focused on the use of 2D coordinates for modelling space use, habitat selection, behavioural classification, social interactions and movement. Here, we submit that many common movement ecology analyses can and should be extended to consider all three spatial dimensions to make more robust inferences about ecological processes. We provide an overview of how home range analysis, network analysis and social network analysis, hidden Markov models, resource selection and step selection functions and hierarchical linear and additive models are used for studying animal movement in two dimensions. Then, we explain how the third dimension, z, can be used within these existing frameworks to consider how depth and altitude affect key ecological inferences drawn from animal tracking data. Our position builds on empirical and theoretical work about how three-dimensional methods can contribute to stronger inferences in movement ecology. Key limitations to operationalisation of this framework include calibration of uncertainty in pressure sensors used to measure depth and altitude, visualisation and rendering of three-dimensional data to make them interpretable and understandable to end-users and generally more conventional and accepted methods for using three dimensions when conducting standard animal movement analyses.