Behavioural Processes最新文献

Group living is widespread in the animal kingdom, which brings numerous benefits and costs to individuals. In nature, refuges for animals are complicated and variable, increasing the survival of animals when they encounter various potential threats, such as predators. Predation, a natural selection force, can induce alterations in the morphology, physiology, and behaviour of prey species in contexts. Indeed, the research on predator-prey interactions has attracted a growing amount of attention from researchers. To address the question of how predation stress and scenarios influence the collective behaviour of fish, our study used crucian carp (Carassius auratus) as the prey fish and northern snakehead (Channa argus) as the predator. We exposed the crucian carp to either a control (i.e., no predator) or a predation stress environment (i.e., northern snakehead) for two weeks. Subsequently, we measured the collective behaviour of each treatment across three ecological contexts: open water, food, and food + refuge. We found that, contrary to our prediction, predation stress exerted no effects on the collective behaviour (e.g., individual swimming speed, synchronization of speed, inter-individual distance, nearest neighbor distance, group polarization, group speed, and group percent time on moving) of crucian carp. However, the splitting number of the fish group was higher in the predator stress treatment compared to the control treatment across three conditions. Additionally, in both the food and food + refuge conditions, the foraging latencies were shorter in the predator stress treatment than that in the control treatment. Consequently, in the food + refuge condition, the duration of stay in the refuge was shorter in the predator stress treatment than the control treatment. The synchronization of speed was found to be lower in the food conditions compared to the other two conditions in both the control and predator stress treatments. Conversely, the group cohesion of the fish, as reflected by inter-individual distance and nearest neighbor distance, was lower in the food + refuge context than in both the open-water and food conditions for two treatments. Our findings suggest that it is the context, rather than two weeks of predator stress, that predominantly influences the collective behavior of fish. However, predator stress may enhance the frequency of fission-fusion dynamics during the collective movement of the fish irrespective of conditions.

Brood parasitic cuckoos usually remove one host egg before laying their own. The purpose of this behaviour is still not fully understood. Recent studies that investigated cognitive mechanisms underlying egg removal found that cuckoos preferentially remove brighter eggs because darker eggs may be more cryptic. However, the role of chromatic differences (e.g., in hue) has been overlooked, despite being key cues in avian egg recognition. Using red and green model eggs and video recordings of experimental nests, we found that common cuckoos (Cuculus canorus), preferred removing red model eggs in 92% of cases. Such a strong preference for eggs of a certain hue indicates that cuckoos use chromatic cues to selectively remove eggs from host nests. Avian visual modelling revealed that it is unlikely that the preference for red eggs was elicited by higher conspicuousness of red eggs in nests. We speculate that cuckoos might have been attracted to red-coloured eggs similarly to how other bird species are attracted to red-coloured food. These findings contribute to better understand the purpose of egg removal in brood parasites.

The present report aims to examine models that best describe the temporal structure of walking and immobility in Drosophila melanogaster, using data from a public repository (Maesani et al., 2015). Two candidate models were evaluated: a power-law distribution, which implies criticality in the neural networks underlying these behaviors, and a geometric distribution, which suggests stochastic competition between neural circuits governing two mutually exclusive motor states. The results indicate that both models provide satisfactory fits to the observed spontaneous walking-resting behavior. Both models provide an alternative framework for understanding internal neural mechanisms through the observation and quantification of overt behavior. These findings underscore the importance of testing alternative models to more accurately characterize the underlying dynamics of behavioral organization.

This study investigates the optimal daily foraging strategy of predators that encounter two distinct types of prey. While the classical prey model is derived under the assumption of an infinite foraging duration, a stochastic simulation model was developed to incorporate finite foraging durations. The classical prey model yields two major predictions: the zero-one rule and the independence of the optimal strategy from the density of the less profitable prey. In contrast, the simulation model revealed that the optimal strategy involves partial preference (a deviation from the zero-one rule) and depends on the density of the less profitable prey. Thus, neither key prediction of the classical prey model held under finite foraging durations. Because empirical studies have also frequently failed to support the classical model, previous theoretical studies have attributed these discrepancies to species-specific biological complexities, such as predator cognitive limitations. The present simulation suggests that finite foraging durations, common to all species, can by themselves account for some of these deviations. Moreover, incorporating finite foraging durations may further alter the outcomes of models that include detailed biological mechanisms if those models remain based on an infinite foraging duration.