Behavioral Ecology and Sociobiology最新文献

The group augmentation hypothesis states that individuals gain benefits by increasing group size and is rarely studied because it often overlaps with other evolutionary mechanisms like reciprocity. When rescuing a fellow prey from death, the mere presence of that member in the group can yield different benefits that can be passive like risk dilution or active like delayed reciprocity. We were able to separate the effects of passive and active group augmentation benefits by experimentally manipulating the behaviour of prey (altruist vs. non-altruist) in a video game where the costs and benefits of altruism were easily measured. The game pits four players-prey that must acquire resources to survive, while avoiding getting captured by a fifth player-predator. We instructed half of the prey players to avoid rescuing other prey, and the other half to rescue when possible. Our data showed that increasing the frequency of altruistic prey in a group increased survival of all group members. Maintaining group size yielded passive benefits like improving resource acquisition and facilitating future rescues. These passive benefits had a higher impact on survival than the active benefits (e.g., being rescued in return through reciprocity). Thus, we were able to support the importance of passive benefits from anti-predator altruistic behaviour using a biologically relevant online video game.

Migration is a life-history trait that shapes individual-by-environment interactions, affecting fitness. Currently, many species are changing their migration strategies, stressing the need to identify and better understand the behavioral correlates of migration. As a partial migrant, the noctule bat, Nyctalus noctula, allows for rare intra-specific investigations of the potential behavioral causes (or consequences) of variation in migration. Here, we combined in-situ behavioral assays with stable isotope analyses to investigate whether spatial and acoustic responses to a roost-like novel environment correlate with migration strategy (local or distant). Given a migrant’s more frequent exposure to novel environments, we predicted migrants would enter a novel environment more quickly and show stronger spatial and acoustic exploration activity. However, individuals of local and distant origin did not differ in acoustic exploration (call activity per unit space), nor, contrasting to several bird studies, in spatial activity (number of chambers visited). Surprisingly, local individuals were more likely than migrants to enter the novel environment. Our findings suggest that small-scale exploration does not vary with migration, potentially because of similar selection pressures across migration strategies on small-scale exploration (e.g., exploration of roosts) as opposed to large-scale. Yet, our findings on the likelihood of entering a novel environment suggest that locals may be more risk-taking. Repeated measures would be necessary to determine if personality differences are underlying these responses. Our unique approach, combining behavioral assays with isotopic geolocation, gave us novel insight into an elusive taxon, highlighting the importance of studying behavioral correlates of migration across various taxa.

In many gregarious species, sex-specific differences can lead to significant variation in movement patterns and, consequently, to social and spatial segregation by sex within the population. Specifically, in several long-distance migratory shorebird species, reverse sexual dimorphism has been proposed as a driver of spatial segregation during the non-breeding season. Thus, sex-specific costs associated with space use during these stationary periods could differentially condition subsequent movement patterns between females and males in these species. Using satellite tracking technology, we analyzed the space use and movement patterns of a population of Hudsonian godwits (Limosa haemastica), a gregarious long-distance migratory shorebird, during the non-breeding season in Chiloé, Chile. We predicted that larger females would show more restricted movements and higher local site fidelity, while smaller males would be less competitive and more exploratory. Most individuals exhibited restricted space use (i.e., a home range), while a smaller fraction showed exploratory movements leading to a nomadic movement pattern. Most of these nomadic individuals subsequently oversummered in Argentina rather than migrating back to breeding areas. Contrary to our main prediction, none of the observed movement patterns were sex-biased. Recent evidence suggests that female and male godwits access prey of different sizes within the same foraging sites on Chiloé. Thus, in accordance with our results, and supported by recent additional findings, resource-partitioning within the same foraging patches could reduce interference competition between the sexes by offsetting the competitive advantage associated with the reversed sexual dimorphism of females over males. Finally, we propose these sex differences in foraging strategies could be advantageous for gregarious migratory shorebird populations that show strong connectivity and high site fidelity during and between non-breeding seasons.

When animals are exposed to higher-than-optimal temperatures, they are expected to thermoregulate by decreasing their activity and seeking cooler areas. However, individuals of certain species continue performing reproductive behaviors instead of thermoregulatory behaviors during challenging conditions. This trade-off has been demonstrated in aquatic animals, but not in terrestrial ectotherms. This research gap is important given the relevance of survival-reproduction trade-offs in evolutionary ecology and the pace of current habitat warming. We explored this potential trade-off in territorial males of the lizard Sceloporus ochoterenae, which mate during the hot-dry season in seasonally dry tropical forest. We first assessed the existence of a temporal trade-off between performing push-ups (territorial behavioral display) versus sheltering in the shade (thermoregulatory behavior), then used confirmatory path analysis to explore how it was affected by tree cover, microclimate temperature, and the presence of a conspecific intruder. We found that territories with less tree cover had higher microclimate temperatures, where focal males spent more time performing push-ups at the expense of sheltering in the shade. Focal males also spent more time performing push-ups the longer an intruder was present, who was also affected by the environmental variables. Territorial males spent more time in sunny spots when performing push-ups despite the potential loss of moisture and energy reserves, perhaps because the display is more effective when performed in the open. The potential effects of continued habitat warming on this trade-off could intensify it or driving lizards to change their daily activity rhythms.

Abstract

During risky interactions like social play, motor resonance phenomena such as facial mimicry can be highly adaptive. Here, we studied Rapid Facial Mimicry (RFM, the automatic mimicking of a playmate’s facial expression, play faces) during play fighting between young rhesus macaques (Macaca mulatta) living in a large zoo-housed group. For the first time and in contrast to previous data on highly despotic-intolerant macaques, we found RFM to be present at high frequency in young rhesus macaques, especially when the trigger was dominant over the responder and when both players were subadults. The hierarchical modulation of RFM may be associated with the increased uncertainty and riskiness of play involving a higher-ranking playmate. This highlights the importance of mimicry in improving communication and coordination during such interactions. Interestingly, RFM prolonged playful sessions, possibly indicating a more effective fine-tuning of motor patterns. Moreover, the occurrence of RFM had an effect on shortening the latency to restart playing after a break, possibly acting as an engine to potentially maintain playmates’ arousal. When investigating if bystanders could replicate play faces emitted by the playing subjects, we failed to find RFM, thus highlighting that being directly involved in the interaction might be crucial for RFM activation in monkeys. Even though further comparative studies should investigate the role of RFM across tolerant and despotic-intolerant species, our findings offer valuable insights into the communicative and adaptive value of motor resonance phenomena in regulating social play in despotic societies.

Significance statement

In risky interactions involving competition and vigorous physical contact, such as play fighting, replicating partners’ facial expressions can serve as a strategy to convey positive mood and intentions. Here we investigated the presence and possible roles of Rapid Facial Mimicry (RFM) in rhesus macaques (Macaca mulatta). For the first time, our study demonstrates that communicative strategies, including Rapid Facial Mimicry (RFM), can be both present and frequent in despotic-intolerant macaque species. We demonstrate that the role of mimicry not only prolongs playful interactions but can also be linked to the reinforcement and/or transmission of playful arousal. Our study shows how the adaptive value of motor resonance phenomena may have driven their evolution to cope with challenges during social interactions also for despotic-intolerant species.

Animal personality is a rapidly growing focus of behavioral ecology and increasingly is found to play a significant role in ecological processes. This study builds upon a growing body of literature on the declining reptile species Terrapene carolina carolina (the eastern box turtle) that shows highly consistent personality traits with probable fitness effects. We used this productive study system to show that spatial variation in ecological interactions has not led to divergence among populations in their average boldness, but that some populations have higher levels of variability among individuals. Furthermore, we highlight sex differences in boldness and a potential role for anthropogenic land use change in shaping boldness of T. c. carolina populations. These findings add to the growing body of literature on animal personality and explore the less commonly discussed phenomena of the absence of among-population variation in personality and the potential importance of levels of behavioral diversity within populations.

Consistent individual differences in behavior (“animal personality”) have consequences for individual fitness, evolutionary trajectories, and species’ persistence. Such differences have been documented across a wide range of animals, though amphibians are generally underrepresented in this research area. The aim of our study was to examine consistent individual differences in Dyeing poison frogs, Dendrobates tinctorius. We evaluated repeatability in activity, exploration, and boldness to assess consistency of behaviors across different temporal, experimental, and environmental contexts. We found repeatability in activity and exploration across time and contexts. In contrast, we observed context-specific behavior for our metrics of boldness, with consistent individual differences only for some measures. Further, while activity and exploration displayed consistent correlations across contexts, relationships between activity and boldness were context dependent. Our findings document the presence of consistent individual differences in behavior in D. tinctorius poison frogs, and also reveal context-dependent behavioral differences, highlighting the complex relationship between consistent individual differences and context-specific responses in animal behavior.

Top krill predators such as the Antarctic minke whale (AMW) serve a vital role within the fragile Antarctic sea-ice ecosystem. They are an abundant krill specialist, but their ecological role in the Antarctic remains poorly understood due to their cryptic behavior and remote habitat. It is therefore crucial to develop a baseline understanding of their basic social and foraging ecology. This study uses animal-borne camera tags to quantitatively explore these critical ecological aspects. Twenty-eight tags were deployed on AMW between 2018 and 2019 in Andvord and Paradise Bays around the Western Antarctic Peninsula. Tag data were analyzed with respect to diving, foraging, and social behavior. Results suggest the presence of loose fission-fusion sociality, with individuals forming short-term associations in 60.6% of cases including both foraging and non-foraging contexts. Socializing was significantly more common for larger individuals and resulted in a significant decrease in foraging rates for both shallow (< 30 m) and deep (> 30 m) dives. There were 12 instances of simultaneously tagged individuals that associated with one another in pairs or trios, displaying synchronized spatial movement and diving behavior. These data illustrated the use of group foraging strategies, with high incidence of synchronized foraging dives (67.5% of associated dives) and lunges (64% of associated lunges). Our results provide clear baseline information on AMW sociality and group foraging, which will help direct future studies for more targeted work. This study will improve our ability to understand the relationship between Antarctic species and their environment as climate change continues to alter the ecosystem landscape.

Abstract

Navigating risk of predation is a major driver of behavioral decision-making in small fishes. Fish use personal information from olfactory and visual indicators of risk, and also rely upon social cues to inform behavioral trade-offs between risk avoidance and fitness-positive activities such as foraging. Here, fathead minnows (Pimephales promelas), were captured, clipped and released at 48 field sites chemically labeled with either fathead minnow alarm cue (high risk) or water (low risk). We removed the chemical label after 2 h, then monitored area use by clipped and non-clipped fish. In addition, a shoal was placed in traps in half of the risky and half of the safe locations as a visual social cue of safety. We caught 2919 fish in the first sample, of which 594 were fathead minnows. These were clipped and released. The second sample caught 1500 fish, of which 164 were fathead minnows including 11 bearing marks from the first sample. Non-clipped fathead minnows and northern redbelly dace in the general community, which lacked personal information about risk status associated with trap sites, avoided areas previously labeled with alarm cues for at least 2 h after the source of alarm cue was removed, unless an experimental shoal was present at the risky site, in which case they joined the shoal in the trap. Clipped fathead minnows with direct personal knowledge of risk showed a significant shift away from areas labeled with conspecific alarm cue and a significant attraction toward sites seeded with a shoal. Moreover, unlike non-clipped fish in the general community, clipped fathead minnows were not influenced by experimental shoals at sites previously labeled as risky. These data indicate that the influence of social cues of safety depend on whether individual minnows have access to recent personal information about risk.

Significance statement

Animals use information for making decisions about when and where it is safe. Information comes from direct personal experience and/or from observing the behavior of others (social cues). In this study minnows with different levels of personal knowledge about risk responded differently to social cues about safety. Naïve minnows relied on social cues while minnows with personal knowledge of risk associated with an area ignored social cues. This study, conducted on free-living fish in a natural population, show how fish use information about risk and safety when the risk of predation is highly variable in space and time.

Abstract

Across animal systems, abiotic environmental features, including timing of seasonal events and weather patterns, affect fitness. An individual’s degree of social integration also has fitness consequences, but we lack an understanding of how abiotic features relate to patterns of individual sociality. A deeper understanding of this relationship could be developed from studying systems where these two links with fitness have already been identified. We explored the relationship between individual social behavior and seasonal timing, seasonal length, and weather patterns. We used social network analysis on a sixteen-year dataset of a wild population of hibernating yellow-bellied marmots (Marmota flaviventer). We fit a series of generalized linear mixed models and found that longer growing seasons before winter hibernation and longer winters were associated with increased individual sociality in the following spring. However, later snowmelt was associated with decreased sociality that spring. We found no relationship between individual sociality and various measures of precipitation and temperature. This suggests that seasonal timing and length may be a more important driver of sociality than weather patterns in this system, both as a lag and contemporary effect. Seasonal timing and length may mediate the opportunity or intensity of social interactions. The entwined relationships between the seasonal schedule and weather, and the seemingly contradictory role of winter length and snowmelt, suggests the timing of seasons and its relationship with sociality is complex and further exploration of environment-sociality relationships is required across taxa.

Significance statement

While the adaptive benefits of social behavior are well studied, less is known about how features of the abiotic environment drive variation in individual social behavior. Given increasing stochasticity in the timing of seasonal events and weather patterns, mapping the environment-sociality relationship will provide important insights to the drivers of sociality in the wild. This is particularly salient for species most vulnerable to climate and environmental change, such as seasonal hibernators, like yellow-bellied marmots (Marmota flaviventer). We found that features of seasonal duration were positively associated with increased sociality, whereas the timing of seasonal onset was negatively associated. This work provides empirical evidence towards an important gap in the behavioral ecology literature.