Ethology最新文献

Animal behavior research has significantly advanced our understanding of animals as sentient, behaviorally complex, and often highly social beings. It has also deepened our knowledge of their needs and laid important foundations for how to treat them and their environments ethically and respectfully. It is paradoxical that bureaucratic hurdles and a political push to replace or drastically reduce animal experimentation now increasingly impede this research field. A group of established researchers working in the field of animal behavior covering topics from animal welfare, the consequences of individuality, chemical communication, and behavioral development has now highlighted the urgent need for a more nuanced perspective on animal experiments (Richter et al. 2025).

The debate between proponents, emphasizing the necessity of animal experiments in research, and opponents, raising animal welfare concerns, has led to entrenched positions and a polarized, black-and-white view of the issue. Close to 8 million animals are used in approved experiments across the European Union every year—comprising the ~7.5% being used in animal behavior studies, but also in a wide range of fields, from cancer research to drug testing and more. Here, at the latest, it should become obvious that animal experiments do not fit in just one drawer. They range from simply observing a fish swimming in a tank (a procedure with no burden to the animal) to attaching a small geolocator on a stork to understand its migration route, to conducting highly invasive procedures, for example, in testing cancer drugs or testing the safety of chemicals. While the severity (a measure to estimate the burden to the animals) of these examples greatly differs, all experiments are subject to the same rigorous and extensive ethical approval process. However, the vast majority of animal behavior and welfare studies impose at most only mild stress (the lowest of the severity classes) on the experimental animals. The authors therefore propose that the European severity classification of experimental procedures (Mild, Moderate, Non-recovery, and Severe) should also inform the permitting process, suggesting that lower severity levels correspond to expedited approvals (Richter et al. 2025). Our focus, like that of Richter et al. (2025), is solely on the European situation. However, expanding the discussion to include regulations and procedures in other countries and continents could provide valuable insights.

Placing behavioral research in one category with more intrusive investigations, and the rigorous permitting procedures attached to it, causes serious problems in the field of education: School teachers find it almost impossible to introduce their pupils to live animals and it becomes increasingly difficult—even at the university level—to teach the correct handling of animals to zoology students and to induce a healthy empathy with animals. This

For animals that traverse patchy or dynamic backgrounds, morphological color change can help to stay hidden from predators and prey. The green lynx spider (Peucetia viridans) is a sit-and-wait predator that hunts pollinators and other insects among vegetation. In the field, it is often bright green with variable patterns of white, red, orange, yellow, and purple, and individuals often appear well-matched to their backgrounds. A previous study that relied on human observers to assess color suggested these spiders can shift their body colors to match their surroundings. Our goal was to replicate this work using modern reflectance spectrophotometry to quantify spider colors. Across two experiments (in different years), we collected adult female spiders and assigned them to three differently colored backgrounds in the lab. Unexpectedly, we found little evidence that the spiders in our study shifted their colors to match their backgrounds. However, exploratory analyses revealed that color change did occur, just not as expected, and was likely related to senescence, diet, body condition, or some combination. We discuss these findings in the context of previous work and suggest that the complex nature of color change in this species makes it a promising candidate to provide novel insights for the field.

Animals across taxa form aggregations, with increased defenses as one of the benefits. Some defensive behaviors of grouped animals involve body movements. However, how those behaviors are triggered varies, and how between-individual morphological variation affects them remains unknown. In this project, we explored three drivers of bobbing—an up-and-down body vibration behavior assumed to be a defensive response—with field observations and a lab experiment in one species of the arachnid order Opiliones (Prionostemma sp.2). First, we explored the variation in bobbing duration across groups of a variable number of individuals, as animals could modulate their engagement in this behavior to ensure a successful predator-deterrent behavior. We found that the duration of bobbing increased with group size. Second, we explored the effect of different triggering stimuli that might represent natural scenarios of an approaching predator. We found that a touching stimulus (gentle stick touching) triggered longer bobbing than an airflow stimulus (gentle blow). Third, we explored if the individuals' leg condition (whether they had all eight or fewer legs when found) affects their engagement in this behavior. We found that variations in leg condition did not affect their defensive engagement, as bobbing duration was similar between intact individuals and those missing legs. Together, these data provide novel observational and experimental insights into the drivers of collective behavior in animals. While individual variation in morphological conditions does not affect bobbing in these understudied arachnids, variability in group size and the triggering stimuli impacted their engagement in movement behavioral defenses.

Sometimes we should take a closer look at the natural behaviour of even the most familiar domestic mammals. An example is the nesting behaviour of the female European rabbit Oryctolagus cuniculus and her offspring. After giving birth in a nest of dry grass and fur, mothers return to briefly nurse once a day and deposit faecal pellets there. In domestic rabbits, we examined the temporal pattern of mothers' defecation in the nest, the response of pups to these faeces and the effect of these and nest hay on pups' pre- and postweaning growth and survival. In Experiment 1, we tested primiparous and multiparous mothers given a nest box and hay and allowed access to their pups once a day to nurse. We recorded daily the number of faecal pellets deposited in the nest and the number nibbled by the pups until weaning on postnatal day 30. Mothers defecated in the nest until around postnatal day 12. The pellets and hay then started to be nibbled by the pups, and histological analysis showed that pups ingested plant material. We found no difference in maternal behaviour between primiparous and multiparous females. In Experiment 2, we investigated the growth and survival of pups before and after weaning: (1) with hay and mother's faeces present in the nest; (2) without hay; (3) without mother's faeces; and (4) without hay or mother's faeces. In condition 1, pups transitioned to solid food with little sign of digestive pathology, whereas in conditions 2 and 3, and particularly in condition 4, pups developed diarrhoea and several died. Thus, the presence of nest hay and mother's faeces appear to contribute to pups' transition to solid food. We conclude that rabbits show a well-coordinated pattern of behaviour between mothers and their preweaning offspring, likely relevant to the appropriate management of domestic rabbits.

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.