Ethology最新文献

Self-grooming is an ancient and innate behavior observed across numerous animal species, serving essential survival functions such as parasite removal, thermoregulation, and stress regulation. In rodents, self-grooming is often characterized by stereotyped sequences known as syntactic chains. However, the extent of their variability across social contexts remains unclear. In this study, we used information theory metrics (entropy and linearity) in combination with network analysis to systematically evaluate the variability and organizational patterns of grooming sequences in male common hamsters (Cricetus cricetus) under three experimental conditions: water-induced grooming (WT), male–male interaction (MT), and male–female interaction (FT). We found significant differences in sequence structure across conditions. WT demonstrated the longest grooming sequences, whereas FT showed the shortest. Water-induced grooming exhibited high entropy and low linearity, suggesting greater behavioral variability and less stereotypy. In contrast, social contexts (MT and FT) showed the opposite pattern, reflecting more stereotyped and structured sequences. Network analysis revealed no significant differences in modularity indices, suggesting that the overall network structure of self-grooming elements is similarly organized across contexts. However, transition probability matrices identified distinct context-dependent patterns. Specifically, WT sequences were cyclic, with frequent returns to forepaw licking, whereas MT and FT sequences were shorter and more directed, typically concluding with anogenital grooming. These results suggest that hamster self-grooming is a flexible, context-dependent behavior, with social interactions promoting more structured and less variable sequences. Our integrative approach, combining information theory and ethological analysis, provides a robust framework for investigating behavioral organization. The quantitative metrics of entropy and linearity offer objective measures for assessing how various factors influence self-grooming patterns, demonstrating that social context significantly impacts structural organization by reducing variability while increasing behavioral stereotypy.

Daytime microhabitat selection is shaped by both physiological traits and environmental pressures, yet nocturnal microhabitat selection remains poorly understood in many species. In urban brown anole lizards (Anolis sagrei), daytime perch selection is influenced by morphology, thermoregulation, and competition, but the factors shaping nocturnal perch selection in urban populations are less clear. We examined sleep site selection at night in adult male, adult female, and juvenile brown anoles in an urban population in New Orleans, Louisiana. Larger individuals perched marginally higher than smaller conspecifics, though perch height did not differ significantly across groups. Within juveniles, higher body temperatures were associated with lower perch heights, a pattern not observed in adults. This difference may reflect active thermoregulatory behavior on the part of juveniles, or passive heat gain resulting from lower thermal inertia. Most lizards slept facing the stem of the plant, suggesting a defensive posture toward potential ground-based predators. Individuals also slept in dark sleeping perches, with most observed at light levels below 1 lx, microhabitats that may reduce predator detection or exposure to artificial light at night (ALAN). Overall, sleep site selection in this urban population of A. sagrei exhibits marked variation within the studied population, and likely reflects the combined influence of morphology, light exposure, predation risk, and age-specific constraints.

Many animals display phenotypic plasticity in various traits. The induced changes can lead to the evolution of novel traits. The evolutionary potential of plasticity is heightened if traits are involved that affect reproduction. In many instances, however, it is not known if phenotypic changes are permanent or reversible. I tested if the plastically induced changes in mating songs and song preferences of the cricket, Gryllus rubens were permanent or reversible. This species has two generations per year (spring and fall) and songs and preferences change in parallel between generations as the result of the thermal environment. I reared males and females as juveniles until adulthood at one temperature (“cool” or “warm”), recorded males and tested female preferences for the songs, and then kept the animals for 1 week at the other temperature (“warm” or “cool”) and rerecorded males and retested females to test if the initially induced songs and preferences changed after exposure to the other temperature. The pulse rate of male songs increased significantly after increasing the rearing temperature from “cool” to “warm” and decreased significantly when decreasing the temperature from “warm” to “cool.” Female preference changed significantly and in parallel with the songs, that is, female attraction for the “warm” song increased and that of the “cool” song decreased after increasing the rearing temperature from “cool” to “warm” for 1 week. Females displayed the opposite attraction pattern to the stimuli when reducing the temperature from “warm” to “cool.” Reversible plasticity in G. rubens' communication could be adaptive to keep it functional in the face of thermal fluctuations within and between reproductive generations. In more general terms, parallel plasticity of songs and preferences allows communication systems to acquire phenotypic variation necessary to evolve, despite the need for both to remain matched.

A well-established paradigm to assess fear sensing is the exposure to alarm substances (AS) from conspecifics in Ostariophysi fish, such as zebrafish, which causes several physiological and behavioral changes associated with distress. Although exposure to AS has been increasingly used to study various aspects related to threat perception, the general effect of fear sensing on agonistic behavior is understudied. Interestingly, while consecutive agonistic encounters modulating aggressive behavior are well studied in males, the extent to which social behavior can be altered by fear sensing during consecutive agonistic encounters remains unexplored. The aim of the present work is to examine whether fear sensing after two consecutive exposures to AS alters agonistic behavior in female zebrafish. Moreover, since female aggression is understudied when compared to males, this study also assesses possible differences according to the reproductive stage. We performed intrasexual dyadic encounters between female zebrafish to determine if agonistic behavior is altered during two consecutive contests and by the presence of AS. To control for the biological effect of the AS, individual behavioral parameters such as distance, mean velocity and freezing were determined during a first and a second exposure to AS. We then quantified agonistic behaviors during dyadic encounters, such as the latency to the first aggressive display, freezing (a well-established behavior associated with fear response after one acute AS exposure) and time of aggression, as the total time in which opponents engage in agonistic interaction. When comparing agonistic behavior in different reproductive stages, results suggest there are no differences in latency and in freezing. Regarding time of aggression, while there are no differences between contests in prespawning or postspawning, significant differences are detected between postspawning dyads and mixed dyads with both females in different reproductive stages. Results suggest that exposure to AS reduces female motivation to engage in an agonistic encounter while aggressive behavior is still maintained despite sensing AS as a potential threat, regardless of corresponding to the first or second contest. To the best of our knowledge, this is the first evidence assessing how consecutive agonistic encounters with a real opponent can be altered by repeated exposure to AS.

In birds, vocal interactions are essential during reproduction. However, the majority of studies on vocalisation discrimination and mate preferences in birds are biased in favour of females. Indeed, few studies have focused on male perception and preferences for female vocalisations. Thus, this study aims to determine male preferences for a type of female vocalisation in the domestic canary, Serinus canaria. To do this, we tested sexually receptive males in an operant conditioning test. The males tested were given the opportunity to choose between two keys and pressing the keys triggered the broadcast of female-specific copulation solicitation trills (CST) with a different number of notes per second. This experiment did not reveal preferences that could be generalised to the group but individual preferences could be highlighted. Further studies will be needed to explain these results and to better understand male preference in monogamous species.

Facilitative interactions between invertebrates and vertebrates are rarely documented, especially those involving trophic mechanisms. Here, we report a novel case of facilitation between the stingless bee Trigona spinipes and the nectarivorous bat Glossophaga soricina, observed in an urban coastal area in southeastern Brazil. Bees were seen wounding pedicels of Senna macranthera trees during the day, inducing sap exudation. At night, bats visited these sap sources, licking the exudate without creating wounds themselves. This observation represents a rare case of indirect trophic facilitation involving distantly related taxa and expands our understanding of cross-taxon interactions in urban ecological contexts.

Cichlid fishes have long been a popular model for ecology and evolutionary biology. Not only do they exhibit nearly unparalleled taxonomic diversity, but their community structures are both complex and extremely dense. Niche partitioning along dietary axes has been credited with maintaining cichlid biodiversity in a broad sense; however, it is common for cichlid species with overlapping diets to co-exist, leading to the search for other mechanisms to explain the maintenance of cichlid biodiversity. Behavioral variation has the potential to drive fine-scale (i.e., micro-) habitat partitioning, but analyzing complex animal behavior poses several challenges, including time, cost, and reproducibility. Modern tools, such as Machine learning (ML), ease the burden of behavioral analyses and are increasingly used in the field. Here, we present the application of tools from a well-developed sub-field of ML, Computer vision (CV), to extract locomotor behavioral data from four Lake Malawi cichlid species. Our dataset consisted of low-resolution (320 × 240), 24 h infrared videos of activity in 4 cichlid species. We first analyzed a pair of species with divergent behaviors, diets, and habitats (i.e., Abactochromis labrosus versus Tropheops kumwera), representing a proof-of-concept comparison. Next, we analyzed activity in two closely related species with broadly similar behaviors and overlapping diets and habitats (i.e., Maylandia sp. “daktari” versus Maylandia fainzilberi). In both comparisons, our analysis involved the quantification of tank usage patterns and stop/rest activity, as well as the statistical testing for differences in these behaviors between species and between times of day within species. Our data align with the known ecologies and behaviors of the species in our proof-of-concept comparison and also reveal novel behavioral differences between all species, especially as related to variation in tank usage from day to night. Our approach provides a window into potential cryptic patterns in behavioral niche partitioning, as well as a foundation for future, high-throughput analyses to study the genetic basis and evolution of behavior.