Impact of exploration behavior, aptitude for pellet consumption, and the predation practice on the performance in consecutive live prey foraging tests in a piscivorous species

Abstract

Within the predator–prey relationship, predator behavior is less studied. Even in natural populations, it shows great diversity, and the factors influencing this are even less known. Among these factors, the personality type of the individual, (including exploration, and neophilia) and the practice significantly influence the success of adapting to a changing environment and switching to new prey types. In the present study, we investigated the first five consecutive foraging trials on live fish prey in naïve pikeperch individuals, which previously consumed or refused pelleted food. We hypothesized that individuals which were willing to consume alternative (pelleted) food would also show higher foraging success on living prey and that the practice would influence the learning process. Our results show that the timing of prey detection is influenced by exploratory behavior, the latency of the first attack by the aptitude for consuming pellets, and both traits by the individual’s practice. However, neither of the factor affects the latency and success rate of capturing the prey, suggesting that predation is an independent behavioral trait.

Altruistic behavior in mother-calf pairs of bottlenose dolphins (Tursiops truncatus) and the possible role of the social bond: a preliminary study

Abstract

In this study, we tested two mother-calf pairs of bottlenose dolphins in a helping task. Specifically, we provided dolphins with an enrichment tool based on the rope-pulling task paradigm to obtain a resource. The calves were unable to solve the task and get the resource on their own, and then we evaluated whether their mothers helped them. Moreover, we also evaluated whether the social bond strength among mother and calf, measured with the simple ratio index, may play an important role in determining altruistic behaviors. Our findings show that mothers performed altruistic behaviors toward their calves only when they had a strong social bond with them. Indeed, only a mother had a strong social bond with her calf, and only she acted altruistically. Moreover, as her calf grew, their social bond weakened and the mother stopped performing altruistic behaviors. As a result, our data seem to suggest the strength of social bonds has an important role in determining altruism.

Vocal signals with different social or non-social contexts in two wild rodent species (Mus caroli and Rattus losea)

Abstract

The ultrasonic vocalizations (USVs) of rodents play a substantial role in the communication and interaction between individuals; exhibit a high degree of complexity; and are influenced by a multitude of developmental, environmental, and phylogenetic factors. The functions of USVs are mainly studied in laboratory mice or rats. However, the behavioral relevance of USVs in wild rodents is poorly studied. In this work, we systematically investigated the vocal repertoire of the wild mouse Mus caroli and wild rat Rattus losea in multiple social or non-social contexts, e.g., pup-isolation, juvenile-play, paired opposite-sex encounter, female–female interaction, social-exploring, or foot-shock treatment. Unlike the laboratory mice, M. caroli, whose USVs were recorded during pup-isolation and courtship behaviors, did not produce any vocal sounds during juvenile-play and female–female interactions. R. losea, similar to laboratory rats, emitted USVs in all test situations. We found higher peak frequencies of USVs in both these two wild rodent species than in laboratory animals. Moreover, the parameters and structures of USVs varied significantly across different social or non-social contexts even within each species, confirming the context-sensitivity and complexity of vocal signals in rodents. We also noted a striking difference in call types between these two species: no downward type occurred in M. caroli, but no upward type occurred in R. losea, thereby highlighting the interspecific difference of vocal signals among rodents. Thus, the present study presents behavioral foundations of the vocalization context in wild mice and wild rats, and contributes to revealing the behavioral significance of widely used USVs in rodents.

Response of the weeping lizard to distress calls: the effect of witnessing predation

Abstract

Escaping from predation saves life, but costs energy and time. The “threat-sensitive predator-avoidance” hypothesis proposes that prey may modulate their antipredator responses, and thus the associated costs, in accordance with the magnitude of predation risk. This process requires that prey accurately assess this risk by decoding available information from various sources. For example, distress calls are uttered by prey when a predator traps them and can serve as public information on predation risk. Such is the case for the weeping lizard whose distress calls trigger immobility in conspecifics. Here, we tested whether this antipredator response of the weeping lizard is modulated by witnessing predation. We exposed lizards to distress calls alone or paired with models of a prey (conspecific), a predator (snake), or a predatory event (a snake subjugating the conspecific). Data show that the sole presence of the predator or prey paired with distress calls seems not to modulate the antipredator responses. Contrarily, witnessing a predatory event associated with calls intensified antipredator responses; lizards reduced their activity for longer and avoided proximity to the stimuli, which may decrease predation risk by reducing the likelihood of being detected by the predator. We conclude that the weeping lizard can use multisensorial public information to assess predation risk and modulate its antipredator responses.

Appeasement function of displacement behaviours? Dogs’ behavioural displays exhibited towards threatening and neutral humans

Abstract

Appeasement signals are behavioural patterns displaying an animal’s non-aggressive attitude and are hypothesized to reduce the aggressive behaviours in the receiver. In domestic dogs, specific displacement behaviours (i.e., behavioural patterns exhibited without an apparent function related to the ongoing situation), have been suggested to function as appeasement signals. To test this possibility, we assessed whether the occurrence of these behaviours was dependent on a social conflict context, predicting that, if displacement behaviours also function as appeasement signals, they should be more prevalent in a conflict vs. non-conflict context. Fifty-three dogs were exposed to two unfamiliar humans approaching them in either a mildly threatening or neutral way. We categorized the attitude of the dogs towards the strangers as “reactive”, i.e., barking and lunging towards the stimulus, and “non-reactive”, i.e., remaining passive in front of the stimuli. We coded dogs’ displacement activities and modelled their duration or frequency as a function of the interaction between the test condition and the attitude of the dog. Displacement behaviours of “blinking”, “nose licking” and “lip wiping” were associated with a “non-reactive” attitude, independently from the test condition, confirming an association with a non-aggressive intention. “Head turning” was associated with a “non-reactive” attitude in the threatening condition. In conclusion, dogs with a non-aggressive attitude exhibited more putative appeasement signals; however, these were not strictly associated with a conflict-ridden situation, calling for further investigation of their function.