acta ethologica最新文献

Heterospecifics eavesdrop on mobbing calls and respond with appropriate behavior, but the functional aspects are less studied. Here, I studied whether jays (Garrulus glandarius) eavesdrop on blackbird (Turdus merula) mobbing calls in comparison to blackbird song. Furthermore, it was studied whether jays provided with extra information about predators differ in their response. Three different experimental designs were carried out: (1) control playback of blackbird song to control for the species’ presence, (2) experimental playback of different mobbing events of blackbirds towards different predators, (3) experimental playback similar to (2) but combined with different predator models. In the combined experiments, mobbing calls were tied to the respective visual stimuli. Comparing the experiments with and without predator presentation, a similar number of jays occurred during the playback-only experiment (n = 7) and the playback combined with model presentation (n = 6). However, during the playback-only experiment, jays approached the speaker closer and stayed for longer time in the nearer surrounding. These results show that jays need extra information to make an informed decision.

Ecological factors may affect resource availability and distribution, impacting foraging and burrow construction behaviours. Clyomys laticeps is a caviomorph rodent with subterranean habits occurring on the Brazilian Cerrado domain (savanna-like) until the Paraguayan Chaco. We investigated their underground system’s architecture taking into account the vegetation and climate. We hypothesised that the sparse food distribution in the winter would promote longer tunnels and more complex architectures to connect more distant foraging areas, supposing that the species moved underground to avoid predators; moreover, the winter would promote food storage. We excavated eleven Clyomys underground systems and measured their size and internal parameters (tunnel and chamber width, length and depth) and complexity (linearity and convolution). We noticed that half of the systems were in the open landscape (OL) and half on vegetation covered (VL). If the anti-predation theory was right, we would find shorter tunnels on the VL systems. We found systems from 2 to 24 m² and up to 22 m long. The deeper and biomass scarcer tunnels were on VL during the dry season, supposedly when animals would need underground water but not stocked food (the palm season). Also, they were more complex (higher circularity and convolution indexes) in OL, favouring our anti-predation hypothesis. Furthermore, Clyomys burrows offer refuge for other species such as arthropods, snakes, amphibians, and birds. We conclude that systems’ architecture is related to vegetation presence and seasonal foraging challenges. This rodent may construct its systems for shelter, food storage and as a safe trail among foraging areas.

Wolf packs perform group vocalizations called chorus howls. These acoustic signals have a complex structure and could be involved in functions such as strengthening of social bonds, territory advertisement, or spacing between packs. We analyzed video recordings of 46 chorus howls emitted by 10 packs of wolves held in captivity, in order to investigate whether sex, age, social status, pack, or individual influence the way wolves participate in a chorus. We found that, during a chorus, wolves vocalized 63% of the time, with the howl being the most common vocalization (36% of the chorus duration), followed by woa (13.5%), other vocalizations (11.8%), and bark (1.7%). The main factor affecting the vocal behavior of wolves was age, since young wolves vocalized less and uttered shorter acoustic signals than adults. The discriminant analysis carried out with the wolves of Cañada Real pack assigned 89.3% of the cases to the correct individual, which is much better than the assignment expected by chance, suggesting that individuals could have a unique vocal usage during a chorus howl, mainly due to the use of howls and woa-woa howls. Based on our results, we propose that in the context of a chorus the woa-woa howl is important, although further research is needed to address this issue properly.

Common across various taxa, infanticide is a highly variable phenomenon present from insects to birds to mammals. In felids, antagonistic sexual coevolution led to the development of female counterstrategies to infanticide spanning particular sexual behavior, physiology, and social strategies. Numerous protective behaviors are well documented for large felids such as lions, cheetahs, and pumas that rely on cooperative defenses and polyandrous mating to protect their cubs from infanticide. Nevertheless, little is known about other wildcat species adopting such behaviors. Solitary and enigmatic, jaguars (Panthera onca) are the largest cat existing in the Americas. Little is known about this big cats’ reproductive and rearing behavior, mainly due to its secretive nature. Here, field observations in two major wetland ecosystems of South America show new and unique findings on female jaguar counterstrategies towards male infanticide. Our findings suggest that, like their big cat relatives in Africa, jaguars have evolved behavioral counterstrategies to protect their young in response to antagonistic sexual coevolution.

Though biological invasions constitute one of the biggest threats for global biodiversity, our understanding of the mechanisms that enable invasive species to outperform native species is still limited, especially, in terms of behavior. Most available studies have examined behavioral traits which favor invasive species on the later stages of invasion, however, our knowledge on earlier stages, namely, when alien species face novel environments and must exploit new resources, remains obscure. Here, we focus on one crucial behavioral trait, finding food. The Italian wall lizard (Podarcis siculus) has been widely introduced and established viable populations in S. Europe and N. America. We examined whether P. siculus has enhanced exploratory behavior and abilities to find food compared to two native congeneric species with which it may come in contact in the near future, an insular endemic (P. milensis) and a widely distributed lizard (P. erhardii). We performed a Y-maze experiment, in which we varied arm markings in a standard way to prevent learning. Podarcis siculus was more efficient than its congenerics in finding and consuming food. This exploitative superiority was persistent, more frequent and repetitive. Interesting behavioral differences were also detected within the native species. Some P. milensis individuals showed no interest in exploring the maze, while few P. erhardii individuals remained rather indifferent to food even after detecting it. Our results suggest that the invasive P. siculus displays behavioral traits that could provide better opportunities for survival in the new environment and thus facilitate establishment even in the presence of congenerics. This provides further support to the idea that behavior plays a crucial role in animal invasions.

Dominance hierarchies are typically stable, with dominants occupying central positions in social interaction networks. However, system perturbations, such as the removal of individuals, may cause instability, which varies according to the group’s resilience. If the hierarchy undergoes a restructuring, this can occur through a dynamic process of self-organization (Social Dynamics hypothesis) or through the influence of individuals’ attributes (Previous Attributes hypothesis). We analyzed the resilience of the white-lipped peccary hierarchy after the alpha’s death and observed how the rise of a new dominant occurred. Additionally, we evaluated the validity of these two hypotheses in the restructuring of the system. We observed the group of white-lipped peccary males of the Municipal Zoo of Curitiba, PR, Brazil, from May to October 2018. We recorded and analyzed the agonistic and affiliative interactions, and we collected data from the attributes: weight, testicle size, testosterone serum and age, before and after the dominant’s death (August). Due to this perturbation, the hierarchy started to show instability, but proved to be resilient. There was an increase in agonism and more than one individual pleading for the new dominant position, which was occupied by a subordinate male. Affiliative interactions were also important in the rise of the new alpha. The hierarchy was well ordered by the social dynamics among individuals, but weight and testicular volume were also correlated with the status of the individuals before, and with the serum testosterone after the alpha’s death. Thus, both hypotheses affected the restructuring of this system.

The domestic dog (Canis lupus familiaris) is known to have evolved from gray wolves, about 15,000 years ago. They frequently exist as free-ranging populations across the world. They are typically scavengers and well adapted to living among humans. Most canids living in and around urban habitats tend to avoid humans and show crepuscular activity peaks. In this study, we carried out a detailed population-level survey on free-ranging dogs in West Bengal, India, to understand the activity patterns of free-ranging dogs in relation to human activity. Using 5669 sightings of dogs, over a period of 1 year, covering the 24 h of the day, we carried out an analysis of the time activity budget of free-ranging dogs to conclude that they are generalists in their habit. They remain active when humans are active. Their activity levels are affected significantly by age class and time of the day. In addition, we provide a detailed ethogram of free-ranging dogs. This, to our knowledge, is the first study of this kind, which might be used to further study the eco-ethology of these dogs.