Ethology最新文献

Animal vocalisations are widely used to signal strength or motivation of a caller in competitive interactions, such as in territorial defence. Substantial understanding of signalling functions in territorial conflicts is based on singing by male songbirds. Yet, in many species, both pair members call during territorial conflicts, as well as in predator-induced situations, leading to complex signalling interactions in which calls overlap or alternate. This raises the question as to whether or not variation in how individuals in pairs time their calls is perceived as meaningful by receivers. Here, we tested with playback experiments whether Eurasian magpies (Pica pica), a species producing alarm calls (so-called chatter calls) in territorial defence, respond stronger to simulated pair-intruders who overlap their calls with each other than to those who alternate them. Magpies emitted a significantly longer first chatter calls in response to playback with overlapping calls but chattered significantly sooner and approached the loudspeakers significantly more closely in response to playbacks of alternating (and therefore longer) call sequences. These findings exemplify that the timing of calls by pair members matters, but in more complex ways than we predicted. The overlapping playback appeared to trigger a longer yet later initial chatter response and a weaker approach response, suggesting that the different ways in which magpies respond reflect different levels of arousal or defence strategies. The results may also reflect uncertainty by receivers due to a potential mismatch between signalled and perceived information: While overlapping calls may signal high arousal by both callers, a longer alternating sequence could be perceived as a more aroused longer signal. These findings expand on classical experiments on call function, suggesting that pairs can vary the message by coordinating their alarm calls in different ways, similar to how duetting pairs time their song contributions in advertisement signalling.

The overarching goal of neurobiology is to understand how complex behaviors are generated by the nervous system. The behavior of each species, and the brain that controls it, is shaped by the historical and current state of the environment that they inhabit. This fact is juxtaposed with the reductionist approach of neuroscience that isolates animals from their natural environment. Understanding how brains evolved to orchestrate the myriads of natural behaviors an animal performs in response to its environment requires an integrative approach to neuroscience that considers ecology, ethology, and evolution. Current technological developments are leading us to an inflection point at which studying brain functions in the wild is now possible. Ecological studies on how the environment affects behavior of animals (i.e., hibernation, foraging, food hoarding, and nest building) have framed a plurality of questions to be answered mechanistically, and yet, only few studies have addressed the relationship between the environment and the brain's anatomy and physiology. Neuroscience needs new animal models that allow us to tackle such questions in the wild. Here, we propose a new animal model for wild neuroscience, the agouti (Dasyprocta spp.), a large wild rodent playing a critical seasonal role in the maintenance of the central and south American rainforest ecosystems. We focus on how a rodent model, like the agouti, will allow for the investigation of large-scale brain dynamics during seasonal behaviors of ecological importance: scatter-hoarding and retrieval. We describe agouti evolution, ecology, and physiology as well as neuro-anatomical and neurophysiological studies, which have set the foundation for future neuroscience in natura. We suggest agoutis have the potential to be a groundbreaking model for wild neuroscience.

Gray mouse lemur, Microcebus murinus, mothers either cooperatively breed plurally with kin or breed solitarily. We describe the first observations of cooperative and solitary mobbing to defend offspring by wild cooperative breeding gray mouse lemur mothers in Kirindy Forest, Western Madagascar. We observed four groups of cooperatively breeding mothers and their offspring daily between 18:00 and 04:00 from January 1 to 15, 2023. Cooperative mobbing was observed twice, and solitary mobbing by a single cooperative breeding mother was observed once. There was one Malagasy tree boa, Sanzinia madagascariensis, per mobbing event. Mothers solitarily mobbed by directly approaching within 1 m of the boa, walking and changing distance while within 1 m of the boa. In addition to the solitary mobbing behaviors, cooperatively mobbing mothers approached the boa together from the same or different directions or alternated, and they gathered around the boa. Mothers collaborated in the context of offspring defense from predators and performed different complementary tasks: mobbing while another provided alloparental care by guarding the offspring of the association, that is, babysitting. Mothers performed similar mobbing behaviors and occasionally synchronized in time or coordinate in time and in space to approach from different directions and gather around the boa. Mothers did not come in contact with the boas during mobbing but kept a distance of at least 20 cm. On two mobbing events, the boa rose up with its head facing the mobbing mothers and climbed down the tree after the mobbing. Cooperative mobbing to defend offspring likely evolved by kin selection but reciprocity and an interaction between kin selection and reciprocity cannot be ruled out, since gray mouse lemur mothers cooperatively breed with kin and basically allonurse reciprocally.

Different environments place different cognitive demands on constituent taxa. Learning and memory involve cognitive processes with associated costs, and it is expected that different levels of learning will occur in taxa from different environments. Greater memory loads linked to increased environmental complexity require greater learning and memory capacities. We investigated the variation in learning and memory in sister taxa of striped mice (genus Rhabdomys). We studied two populations each of the mesic grassland-occurring R. d. chakae and the mostly arid-occurring R. pumilio. We conducted two sets of experiments. (1) In a novel object recognition (NOR) test, we assessed memory by recording the duration of exploration of similar and novel objects by test mice. (2) In an associative learning task, we assessed whether mice could associate specific scents with or without a food incentive or with different quantities of the food incentive in previous training phases. We measured the latency of mice to contact scents in a two-sample choice in the test phase. In the NOR test, R. pumilio spent less time investigating similar objects in a training trial than R. d. chakae but increased absolute exploration of the novel object when presented with a novel and a familiar object in the retention trial, suggesting a sensitization to the novel object by R. pumilio. In the associative learning experiments, R. pumilio approached the stimuli faster than R. d. chakae, whereas mice from both taxa preferred scents associated with a seed versus no seed and scents associated with 5 seeds versus 1 seed. The data provide evidence of taxon-level differences in learning and memory, likely related to environmentally modulated personality differences between the taxa.

In insects, aging produces deterioration in physiological and cellular functioning, affecting their reproductive potential. Anastrepha fraterculus and Ceratitis capitata are two fruit fly species where overwintering adults resume their reproductive activity in spring, giving old individuals the possibility of mating with young adults. Most age studies focus on male reproductive capacity; however, we lack information on how the interaction between the ages of both sexes can determine post-mating processes. Here, we studied sex and age effects on (i) female fecundity and fertility, (ii) failure to leave viable offspring (reproductive failure), and (iii) female remating behavior. We found that young pairs of both species had higher fecundity, but young C. capitata males mated with old females had the lowest fecundity. This suggests that overwintering flies in this species will not substantially contribute to the next generation. We also found in C. capitata more prevalent reproductive failure in hetero-age combinations, which could be due to age recognition between mates, resulting perhaps in differential ejaculate allocation. Copula duration was positively associated with female age, yet it was longer for older A. fraterculus females and shorter for C. capitata females. Female remating was lower when young females mated with old males in C. capitata. This would imply that males perceive young females of “good quality” and thus invest and transfer all the ejaculate possible to ensure the delay of renewal of female receptivity. Aging does not always cause a decline in reproductive potential, which may be important in species that overwinter as adults. Complex interactions between female physiology and male ejaculate senescence can impact postcopulatory behaviors that affect reproductive success for both sexes.

The eusocial “paper wasp” Polistes dominula is an invasive species that has successfully established worldwide. In the present study, we investigate the foraging behaviour of P. dominula wasps when revisiting previously gathered resources. We recorded the number of learning flights and food manipulation efficiency performed by a single target wasp during several consecutive collecting visits. Additionally, we analysed P. dominula relocating behaviour when dealing with changes in food position. We assessed whether wasps choose the previously visited dish containing food or opt for a novel baited dish placed 60 cm away. Then, we trained wasps to collect food either once or three times and compared the time taken to find the novel food position when it was displaced 60 cm away. This is the first study to demonstrate relocating behaviour in P. dominula in which wasps rapidly learned to return to certain food sites. A significant reduction in learning flights after only one collecting visit was observed. Likewise, wasps learned to manipulate the resource spending less time after each experience. Moreover, when two food sources were offered, after just one visit, the majority of wasps collected the resource from the previously rewarded dish. Furthermore, when food was displaced, foragers found the new food location more rapidly after one visit than after three consecutive collecting experiences. Our findings contribute to the understanding of P. dominula behavioural plasticity while collecting food sources in anthropized environments, which highlight the importance of considering such learning experiences.

During courtship, animals perform conspicuous and elaborate signals. In birds, courtship involved often mutual engagement by both partners but most research on courtship behaviours has focused on male signals despite of growing interest for female signals in recent years. Here, we show that female domestic canaries (Serinus canaria) have the ability to modulate their sexual response to male songs. To do so, we exposed females to two types of song (very attractive and moderately attractive songs) during two consecutive reproductive cycles. We measured both visual (copulation solicitation displays, CSD) and vocal signals (copulation solicitation trills, CST; contact calls, CC and simple trills, ST) emitted by the females during song broadcast. We observed that females could modify the characteristics of their signals (duration and the number of elements of CSD, duration, frequency and number of notes of calls) depending on song attractiveness and the number of times they were exposed to a male's song. We also found that some females always emitted more signals than others (i.e. stable inter-individual differences) regardless of the song attractiveness and across reproductive cycles. Further studies are necessary to check whether female signals constitute sexual ornaments and if they could stimulate male canaries during courtship.