acta ethologica最新文献

Migratory shorebirds such as Calidris alba, C. fuscicollis, and Charadrius semipalmatus congregate in stopover areas like coastal wetlands to rest and feed, building up sufficient energy for their ongoing migration. To investigate the feeding ecology of these three shorebird species during their stopover, we conducted a comparative analysis of their feeding behavior and prey in Lagoa do Peixe National Park. We examined the feeding behavior using video recordings of 594 actively foraging individuals. Additionally, we determined the shorebirds' diet by analyzing 106 droppings collected from two areas within the park: the beach's intertidal zone and the lagoon's mudflats. The results highlighted that shorebird species showed marked differences in feeding strategies and prey captured during foraging. C. semipalmatus employed a visual-run-stop strategy with surface pecking, with no significant variations observed between the beach and the lagoon. The two Calidris species utilized a tactile-continuous hunting strategy, involving pecking and probing, with some variations observed between the beach and the lagoon. Multiple probing was mostly used on the beach, and single probing in the lagoon. The variation in probing behavior between the Calidris species appeared to be associated with differences in substrate type and food availability in the respective habitats they frequented. Additionally, our findings indicated that visual searching led to a more diverse prey selection, particularly in the lagoon. These differences in foraging strategies suggest that shorebird species can exploit the park's intertidal plains and trophic resources differently, emphasizing the importance of considering spatial and dietary variability in studying their foraging behavior.

Tool use by animals, traditionally studied mainly in captive primates due to its relevance to human evolution, has been investigated in both free-ranging and captive mammals. Here, I present a report on tree bark and branch use behaviours by a free-ranging Japanese marten (Martes melampus). The marten put its face in a water-filled container, looking for something, and then it proceeded to make a scooping motion with a bark held in its mouth. Subsequently, it picked up a branch with its mouth and tried to scoop something from the water with it. Upon inspecting the container approximately 2 weeks later, I found a larva belonging to the family Syrphidae. While it is unclear if the marten was trying to catch this larva, its behaviour resembled reach extension behaviour seen in chimpanzees. The use of bark or branches may provide an advantage by allowing access to objects in hard-to-reach positions.

In recent decades, reports on responses to death and dying individuals in non-human animals have been increasing. Here, we report the case of a striped hyena who refrained from eating a juvenile conspecific carcass in its territory. We inferred that the juvenile was an offspring of the individual. Although the hyena discovered the carcass several days before any other conspecific, other than maintaining vigilance over it and sniffing it repeatedly, it did not consume it; only an unfamiliar hyena did so. This is the first documentation of thanatological behavior in striped hyenas.

Annual killifish have an annual life cycle unique among vertebrates. Adults lay desiccation-resistant eggs in the soil of the temporary pools they inhabit. Courtship behavior of some Neotropical killifish consists of a series of displays performed by males and females that ends in the total or partial burial of the couple. However, little information exists on their reproductive isolation mechanisms, including a detailed analysis of courtship signals. In this study, we analyzed the courtship behavior of a Neotropical annual killifish (Austrolebias nigripinnis) within a comparative frame. The most frequent units in males were lateral (44%) and sigmoid displays (26%), where males exhibit morphological and color patterns to females. Females showed a high frequency (44%) of quiescence, suggesting that this unit may have an evaluative role during courtship. Behavioral units recognized in this species show some differences with other related species (i.e., Austrolebias affinis), mainly in frequency and duration, but also in sequence. Although the results of this work cannot determine if these differences constitute reproductive isolation mechanisms, it provides fundamental elements to try to establish kinship relationships and solve the complexity implicit in the definition of species.

While the use of trees has been widely documented for most of the big cats, this information is scant for the jaguar (Panthera onca). In this study, we investigated the use of trees by jaguars, evaluating different underlying reasons as well as the frequency of tree use based on sex, age, and reproductive status. Data were obtained from 2013 to 2020 through a combination of direct observations during fieldwork and camera trapping focused on this behavior in the Brazilian Pantanal. We documented 252 climbing events (176 direct observations, 76 camera captures). Using only camera trapping data to avoid observers’ influence on jaguar behavior, we fitted generalized linear mixed models (GLMM) with jaguar identity as a random factor to test the effects of age, sex, and presence of conspecifics in the odds of animals climbing trees. We also used a generalized linear model (GLM) to test the effect of adult body weight on jaguar tree climbing probability. Age and presence of conspecifics were the most important drivers of jaguar climbing behavior in the study area, with cubs being more likely to climb trees than adults of either sex (odds ratio = 7.91, p < 0.001), and the presence of conspecifics, irrespective of age and sex, accentuated that behavior (odds ratio = 3.26, p < 0.005). Adult females (especially the lighter ones) and cubs were commonly recorded through direct observation on trees, a similar trend to our GLMM that showed a marginally negative effect of body weight on jaguar tree climbing probability. Only a few adult male jaguars ascended trees, and in all cases, these males were following females in heat. We suggest that trees are vertical extensions inside jaguar home ranges and may be safe refuges for resting and for protecting offspring against potential threats, including the harassment of large adult males.

Abstract

Abstract

Animals whose ecological niches largely overlap within a habitat can get into intra-specific and/or inter-specific competition for some of the limited resources available. We hypothesise that differences in locomotor abilities might be a key component deciding which individual will gain the resource, especially in animals with limited agility, such as turtles. To address this hypothesis, we tested self-righting ability and releasing from a vegetation alike rope in two sympatric populations of turtles: Emys orbicularis and Mauremys rivulata. All individuals managed to complete the tests promptly (≤ 103 s). When overturned on their carapace, E. orbicularis had shorter inspecting time, as well as overturning time, indicating slight advantage in self-righting. On the other hand, both species were equally efficient to release from a rope attached to the front of their plastron. The inter-specific morphological differences indicate that muscular strength might be a good predictor of competitive relations among syntopic turtle species.

Toe-tapping, the quick movement of the middle toes of the hind legs, has been observed in many frogs and toads, and is usually associated with feeding, calling, or courtship behaviors. While plenty of observations of toe-tapping exist for different species, experimental evidence regarding the stimuli triggering this behavior is almost non-existent. Here, we systematically tested the influence of different stimuli on the toe-tapping behavior in the green-and-black poison frog (Dendrobates auratus, Dendrobatidae) from a captive colony in the Zoo Frankfurt. We found that, compared to a control, both big and small prey animals (crickets and fruit flies) elicited much more toe-tapping behavior, and that toe-tapping was positively correlated to feeding events. Playback advertisement calls in contrast did not trigger toe-tapping. We further showed that also juvenile frogs already toe-tap, but less frequently than adults. Our results support the observation-based data that toe-tapping is associated with hunting behaviors. While the auditory part of courtship does not seem to trigger toe-tapping, experimental evidence regarding visual and/or tactile courtship stimuli is still lacking.