Ambient light can have a marked influence on the behavior of many species, particularly prey animals, where increased illumination may raise the risk of predation while offering limited advantages for activities such as foraging and mating. Katydids, which depend on species-specific acoustic signals for long-distance communication, are known to be sensitive to environmental conditions. However, the impact of ambient light on paleotropic katydids remains unexplored. The current study explored the effect of ambient light, temperature, and humidity on katydid assemblages at two locations, one in Northeast India and the other in the Western Ghats, over 5 years (2015-2020). We examined possible differences across seasons and between ecosystems at each site. A total of 537 encounters through psychoacoustic monitoring were used for the analysis. The results showed that temperature and humidity had no significant impact. Ambient light had a significant effect on katydid activity, with overall activity peaking near the waxing phase, thereby indicating a strong influence of light. Comparison between ecosystems showed contrasting results across sites, activity peak being more closely associated with the understorey in the Western Ghats and with grasslands in Northeast India. Although elevated light may increase predation risk, especially in open habitats, the consequent impact on the activity level of individual species varies. While previous studies explore the effect of sympatric signallers and predators, our study is the first to explore how the natural environment might affect the signaling activity of katydid assemblages in the Paleotropics.
Understanding the temporal niche of different carnivores and their interactions with humans is crucial for conservation research. This study aimed to investigate the activity patterns of the carnivore community and their responses to human activities in the common leopard (Panthera pardus) distribution area of the Luoxu White-lipped Deer Nature Reserve, Sichuan Province, China. From September 2019 to October 2020, camera traps were used to obtain data on seven different carnivores. Kernel density estimation and generalised linear models were used to study the temporal niche partitioning of these carnivores and their reactions to human and livestock activities. Among the three types of large carnivores, common leopards preferred daytime and twilight and showed limited activity at night; the grey wolf (Canis lupus) preferred daytime; and brown bears (Ursus arctos) favoured twilight and night. Mesocarnivores there were nocturnal. The alpine weasel (Mustela altaica), a small-sized carnivore, was diurnal. The staggered activity peaks among these carnivores indicated temporal niche partitioning, which presumably reduced direct interspecific competition. Furthermore, the relative abundance index 2 (RAI2) of certain species was associated with different environmental and biological factors across different time periods. Common leopards showed no association with elevation during daytime but exhibited avoidance of grey wolf habitats. During twilight, their RAI2 increased at higher elevations and was independent of grey wolf distribution. Brown bear activity was not associated with human presence during daytime but shifted at night to areas that had been used by humans throughout the day. The RAI2 of common leopards showed a negative correlation with distance to settlements. Grey wolf daytime RAI2 was positively correlated with the RAI2 of humans and horses during the same time period. These findings inform management decisions and conservation efforts for ecological communities threatened with human encroachment.
Aggressive mimicry is an ambush strategy observed in various animal taxa, including snakes, which use caudal luring (CL) to attract prey. CL involves cryptically colored snakes waving a conspicuous tail tip (CTT) to mimic worm-like invertebrates, luring prey that feeds on such organisms. This strategy is common among Viperidae, particularly in juveniles, which often exhibit ontogenetic shifts in diet (OSD) from ectothermic to endothermic prey. Although CL, CTT and OSD are assumed to be correlated, this relationship has never been empirically tested. This study investigated the origin and persistence of CL, CTT and OSD in Viperidae evolution, assessing their phylogenetic signal and testing for correlations. Data on the presence or absence of these traits were compiled from the literature, and phylogenetic comparative methods were used to measure phylogenetic signal, test correlations and reconstruct ancestral character states using parsimony and maximum likelihood. Results revealed strong phylogenetic signals for all three traits and significant correlations between each pair. Maximum likelihood reconstructions suggested that the ancestral Viperidae possessed CL, CTT, and OSD, while parsimony analyses indicated CL and CTT were present in the ancestor, but OSD was not. These findings support the hypothesis that CL, CTT and OSD are evolutionarily linked and have been integral to Viperidae since their origin. Despite being the most comprehensive study on these traits, significant gaps in viper natural history data were identified. This highlights the need for further descriptive ecological studies to enhance understanding of viperid biology and support broader macroevolutionary research.
The trade-off between protection and mobility is a central principle in functional ecology and is particularly relevant in terrestrial hermit crabs, which depend on gastropod shells for defense while potentially incurring locomotor costs. Under the trade-off hypothesis, heavier or asymmetric shells are expected to impair movement, especially on heterogeneous or uneven substrates. To evaluate this prediction, we examined locomotor behavior in the land hermit crab Coenobita compressus on Coiba Island (Panama), integrating field observations with controlled experimental assays across substrates differing in topography and compaction. Contrary to classical expectations, shell weight and morphology exerted limited effects on locomotor performance. Instead, individuals exhibited substantial behavioral flexibility, adjusting posture and gait across environmental contexts. These findings suggest that C. compressus may buffer mechanical constraints imposed by shell architecture through adaptive behavioral compensation. Our results support an expanded interpretation of the trade-off framework in which behavioral plasticity attenuates, rather than eliminates, functional trade-offs, potentially enhancing performance in dynamic coastal habitats.
Animal personality is a concept in behavioural ecology that describes consistent inter-individual variation in behavior. These behavioral tendencies are stable across different contexts and throughout an individual's life. Increasing evidence shows that variation in individual personality of animals is related to variation in their cognitive ability (e.g. spatial learning), but the findings on such links are contradictory among and even within species. This study examined how personality traits (boldness and activity) relate to spatial learning in crucian carp (Carassius auratus), specifically to determine their reliance on allocentric (landmark-based) navigation. Fish were trained under two conditions: a visual landmark absent and present. As trials progressed, latency to complete the foraging task and theG number of fish turn-backs decreased in both treatments. However, the percentage of correct choices increased significantly only in the landmark present condition, with no marked improvement in the landmark absent condition. This indicates that the presence of a landmark enhanced learning efficiency, suggesting a reliance on allocentric navigation. Despite this, neither boldness nor activity predicted individual learning performance in landmark present context. Our findings demonstrate that environmental structure, specifically the presence of landmarks, is a critical factor in spatial learning for crucian carp, but the personality traits measured here do not underpin individual variation in this cognitive ability within the tested contexts.
The Swamp deer, also known as the Barasingha, is one of the largest species of deer in the Cervidae family. This study investigates the winter season food and feeding habits of Northern Swamp deer (Rucervus duvaucelii duvaucelii) in Dudhwa Tiger Reserve using vegetation sampling and microhistological analysis of fecal samples. Data were collected during the winter season (January--March 2024), randomly 98 sampling plots were laid at eight different locations within the study area. Ten m circular radius plots were laid along trails/roads at 100 m intervals on either side. In addition, pellet group collection was carried out within 10 m circular radius plots. To aid in the identification of species, 44 permanent reference slides were also prepared. The results showed that 97.4% of the diet consisted of grasses, out of the 28 food plants species that were detected. The results of this study also revealed that five species were consumed in proportion to their availability, 10 were less preferred species and eight were preferred species in the diet of swamp deer. The results based on winter season observations highlight the need to conserve important habitats, such as wetlands and grasslands, for the conservation of swamp deer and provide suggestions to conduct year-round research to better understand seasonal variations and enhance conservation strategies.
Locomotion is both a result and an impetus of morphology; though their interplay is an essential part of natural speciation, almost all domesticated species have been selectively bred so that their morphology better suits human needs. Where many species have been bred for function, many fish in the aquarium trade have been bred for aesthetics. Domesticated male Betta splendens have been bred for their large fins and are available in many varieties, but there is a lack of literature investigating the possible effects of this artificial selection on their behavior. The exaggerated large caudal fins of domesticated Betta are an artificially selected trait that is absent in wild Betta species, leading to questions regarding the possible effects of this selection on locomotion. To measure the effects of fin morphology on swimming behavior, we used a mixed-sex sample of several varieties of B. splendens and the closely related species B. imbellis to obtain a wide phenotypic range. We found that morphological characteristics associated with caudal fin size had a significant negative relationship with burst swimming speed, with caudal fin area and propulsive area ratio explaining the most variation in speed when adjusted for species, sex, and intra-individual variation. These results are consistent with patterns seen in similar studies of other small ray-finned fish and raise questions of the mechanical and behavioral costs of selective breeding in a common aquarium fish.
Growing urbanization affects ecosystems worldwide. Its ecological and evolutionary consequences are receiving increasing interest, on both fundamental and applied aspects. However, as for biodiversity knowledge in general, most studies have been conducted in Europe and North America, leaving other parts of the globe less explored. In Algeria, the Eurasian collared dove (Streptopelia decaocto) has a well-known settlement history and offers a unique opportunity to explore the potential phenotypic consequences of urbanization. Following up a previous study at the regional scale, we compared 13 morphological characteristics, body mass and two body condition indices (Body Condition Index or by Scaled Mass Index) of 35 Eurasian collared doves from two spatially close sites differing in their environmental characteristics (a woody cemetery and a roof-top surrounded by a highly urbanized area) 1.6 km apart within the city of Annaba itself, 20 years only after the species settled there. Some morphological traits were smaller in doves from roof-top compared to doves from woody cemetery, either significantly (extended and folded wing, finger and beak) or marginally (tarsus and beak height), while other traits did not differ (beak width, exposed and total culmen lengths, tail length, total body length, collar length, fifth primary feather length, bill index, relative wing length, body mass). Importantly, doves from both sites had similar body condition (whether estimated by BCI or SMI). In line with previous European and North American findings, these observations shed further light on the spatial (< 1 km) and the temporal (< 20 years) scale at which phenotypic differentiation may occur. Obtained on a limited sample size from two sites, our results highlight the urgent need for developing urban ecology studies in all parts of the world, including in overlooked regions such as Africa, to better understand the ecological and evolutionary consequences of urbanization and their underlying mechanisms worldwide.
Communication through scent-marking plays a crucial role in animal fitness, particularly for solitary species such as the Andean bear, in which it fulfills the function of advertising individual attributes to conspecifics and managing social interactions. However, research on the scent-marking behavior of Andean bears and the impact of free-ranging dogs on their chemical communication remains limited. This paper aims to characterize Andean bears' scent-marking behavior and to study the overlap of their daily activity patterns with free-ranging dogs in a key biological corridor linking the Andes to the Amazon region. We collected data using camera traps in front of 10 trees selected for rubbing by Andean bears. Cameras were deployed in the Gu & aacute;charos-Purac & eacute; Biological Corridor Regional Natural Park (PNRGP), Colombia, from April 2023 to April 2024. We determined the transition probabilities of marking behaviors using finite Markov chains. We compared the time budget for the behaviors displayed by Andean bears at rub trees by age and sex. Finally, we described the temporal overlap of Andean bears and free-ranging dogs and analyzed whether it differed between rainfall seasons. Results revealed significant intersexual differences in the time budget of scent-marking, with adult males investing more time on marking than females and subadults. This behavior was prevalent during the dry season. The daily activity patterns of Andean bears and free-ranging dogs were predominantly diurnal. Both species showed high temporal overlap during the dry season (77%), decreasing during the general analysis (75%) and the wet season (69%). We also suggest an increased potential for interspecific interactions between Andean bears and free-ranging dogs that could negatively impact the former, through competition, altered communication patterns and the potential transmission of diseases. We emphasize the need for further studies on the impact of free-ranging dogs on wildlife, particularly on the intraspecific communication of Andean bears.
The presence of a conspecific can influence individual behavior due to providing numerous benefits, including increased foraging efficiency, enhanced predator detection, and opportunities for social learning. While these benefits often arise from being in groups, the effects of minimal social exposure remain poorly understood and could help to better interpret ecological and evolutionary processes. We examined how social context (individuals tested alone or in pairs) affects locomotor and exploratory behaviors in the gregarious freshwater fish Squalius cephalus. Fish tested in pairs exhibited higher exploration rates than solitary fish, likely reflecting social facilitation and information gathering. Isolated fish showed elevated average acceleration, suggesting more erratic or stress-related movements. Mobile speed, mobility rate, freezing events, and spatial positioning were not significantly affected. These results demonstrate that even the smallest social context (a single conspecific) can influence behavioral components. Our findings highlight the importance of considering social context in controlled experiments and aquaculture practices, as isolation may produce unrepresentative behavioral baselines.
Porcellanid crabs avoid predation by autotomizing their chelipeds, a strategy that enhances immediate survival. In decapod crustaceans, males with larger bodies and chelipeds often outcompete rivals for access to receptive females, suggesting that cheliped loss may reduce reproductive success. We tested this hypothesis in the porcellanid crab Petrolisthes japonicus, a gregarious species inhabiting intertidal cobble and boulder shores, under three autotomy conditions: both chelipeds intact (control), one cheliped autotomized (OCA), and both chelipeds autotomized (BCA). Mating behavior was observed, and female reproductive traits - including spawning, egg number, egg size, and fertilization rate - were assessed, as these factors influence male reproductive success. Two mating experiments were conducted. In experiment 1, a female was presented with two males of different autotomy conditions (control vs OCA, control vs BCA, and OCA vs BCA). In experiment 2, each pair consisted of a female and a male from one of the three groups. Male cheliped loss did not affect mating behavior or the reproductive traits of female partners. In experiment 1, BCA males showed reduced mating success only when competing with control males. In experiment 2, copulation frequency did not differ significantly among groups. These results indicate that the impact of male cheliped loss on reproductive success depends on both the number of chelipeds lost and the competitive context. However, the loss of both chelipeds may severely reduce male reproductive success in P. japonicus under natural conditions.
The Daba Mountains is a critical ecological barrier in central China, with diverse landforms supporting rich avian communities. To clarify the species composition, seasonal dynamics, and vertical distribution of birds in its southern foothills - key for biodiversity conservation - we conducted systematic surveys via line-transect and direct observation methods in June (summer) and September (autumn) 2024, covering multiple habitats and altitude gradients. A total of 72 bird species (8 orders, 31 families) were recorded, including 51 residents (70.83%), 13 summer migrants (18.06%), six winter migrants (8.33%), and two passage migrants (2.78%). Zoogeographically, Oriental realm species dominated (37 species, 51.39%), followed by cosmopolitan species (23 species, 31.94%) and Palaearctic realm species (12 species, 16.67%). Summer avian diversity was significantly higher than autumn (P < 0.05), linked to breeding activities and summer migrants. Across the studied altitudinal range, aquatic habitats consistently showed the highest diversity index, whereas farmland and urban-rural habitats displayed the greatest similarity in community composition. Analysis along the altitudinal gradient revealed that the overall species richness showed a mid-peak pattern, peaking at 800-1100 m, Linear Mixed Model (LMM) analysis further confirmed that elevation had a significant effect on bird diversity, with the 800-1100 m band showing significantly higher Shannon-Wiener index values than lower elevations (P = 0.035), while no significant interaction was found between elevation and habitat type. Resident birds exhibited seasonal altitude range expansions. Our study provides baseline avian biodiversity data for the region, enhancing understanding of avian ecological adaptation in mountain ecosystems. This information is valuable for guiding targeted conservation and ecological management in the southern Daba Mountains.
Besides humans, Rhesus macaques (Macaca mulatta) are the most adaptable primate species that can thrive in most types of terrestrial habitats. Due to their affinity for disturbed habitats, their conflict with local wildlife and humans has increased, especially in India's semi-arid agro-climatic zone of Uttar Pradesh. It was, therefore, imperative to analyse the behavior of this species, especially in urban areas. The behavior of macaques was studied in all seven districts of the semi-arid agro-climatic zone of Uttar Pradesh for two consecutive years, April 2019-March 2021. GPS trackers (GARMIN eTrex 10) were employed to track the movements of Rhesus macaques. QGIS software was utilized to map their locations. A total of 42 troops were identified. Behavioral data was collected by using focal sampling technique. Videography was done once a week in each district. Videos were uploaded to Noldus Technologies' behavior coding software, Observer XT version 14.2 (1703). A holistic ethogram was generated using the focal sampling technique. Kruskal-Wallis ANOVA analysis showed significant variations in Macaca mulatta behavior in urban areas (P < 0.05, H > 12.59). The Rhesus macaque time-activity budgets varied with the seasons. Foraging, locomotion, and play were the most common activities in the spring. Autumn saw increased locomotion, maintenance, conflict, and play. A considerable influence of Macaca mulatta behavior on humans in urban areas was found via multiple regression analysis. To assess how the Rhesus macaques' behavior affects people in urban areas, a survey was conducted. Macaque-human interactions and conflict levels in urban environments can be heightened by factors such as diminished green spaces, food provisioning, high human population density, tourism and religious sentiment. Diverse approaches are needed to address the complex urban macaque-human relations: ecology, policy, education, conservation, law, awareness and urban planning for a successful cohabitation.
Foraging dynamics and energetics play critical roles in pollination efficiency and plant fitness. Bees are among the most efficient pollinators; therefore, understanding their foraging patterns can elucidate their ecosystem services. We examined two aspects of foraging behavior: floral fidelity (a pollinator's consistency in visiting the same plant species) and handling time (the time an individual spends on a single bloom). Unlike previous studies that primarily focus on an individual bee species or simplified habitats, we investigated the foraging behaviors of bee communities within complex pollinator habitats. Study sites included eight research stations across North Carolina. In Experiment 1, we analyzed the pollen grains from five focal bee species caught on 18 different plant taxa to quantify the floral fidelity of individual bees. In Experiment 2, we filmed naturally foraging bees across nine bee and plant taxa to calculate their handling and interflower durations. Comparison of floral fidelity for previously studied bee species was consistent with the literature, but we found substantial variability within and among taxa. Handling time did not vary significantly by pollinator genus, but bee traits (such as body size and tongue length) as well as flower genera, shape, and size played a role. While interflower time likewise did not differ by bee genus, smaller bees were found to have lower interflower time. Our findings suggest that individuals may be visiting more flowers of different species than previously thought, or that blooms may harbor cross-contamination of pollen grains. These results can be used to evaluate habitat effectiveness and inform conservation efforts.
Territoriality in animals is a costly behavioural engagement with severe consequences, often resulting in the loss of one individual's resources. Therefore, behavioural displays are carefully selected and conducted, as their failure may result in costlier physical combats. Here, we studied the agonistic behaviour of a little-studied frog endemic to the Western Ghats of India, Raorchestes luteolus, in response to a simulated territorial intrusion using a playback experiment. We recorded seven territorial behavioural displays, of which the most frequent behaviours in a sequence of occurrences were a vocal challenge, followed by orientation towards the sound source, approaching the source and ultimately deserting their territories at the end of the experimental trial. We found a significant positive effect of temperature on the displacement distance after deserting the territory. Further, for the first time, we report a second call type in this species that we refer to as aggressive call and we provide a detailed description of the advertisement calls. Advertisement calls were complex and each note displayed an initial and main section that varied in pulse rate and number. The two call types differed in their temporal structure, especially in the introductory pulses of the aggressive calls. Alongside adding substantial information on call types, our study details the behavioural sequences displayed by the territorial males in response to simulated threats.
Trade-offs in resource investment between growth, reproduction and somatic maintenance are key drivers of life history evolution. Although extensively studied using single trait selection in Drosophila melanogaster, the evolutionary responses of simultaneous selection on multiple life history traits are largely unexplored. We investigated sex-specific life history traits evolution in Drosophila melanogaster populations simultaneously selected for faster pre-adult development and increased adult longevity (FLJs) as compared to their ancestral controls (JBs). Both FLJ males and FLJ females emerged with reduced resources, yet their evolutionary responses diverged. FLJ males had comparable pre-copulatory traits and reproductive effectiveness, while achieving higher longevity than JB males. In contrast, FLJ females exhibited significantly reduced lifetime fecundity and fewer ovariole numbers with longevity similar to JB females. These findings indicate a clear sex-specific divergence in resource allocation strategies under identical selection pressures.
Fear response to anthropogenic disturbance can shape species behavior and influence their distribution and population health. Fear is species- and situation-specific, but can be quantified by using behavioral indicators such as alert distance (AD), flight initiation distance (FID), and escape distance (ED). In this study, we collected ADs, FIDs, and EDs of the white wagtail (Motacilla alba) in two cities in Finland, Helsinki and Lahti. We aimed to find whether bird age, sex, flock size, pedestrian activity, distance to refuge, land use, built cover or escape method related to any of the indicators and whether these relations differ by city. For analysis, we used linear models (LM) and classification and regression trees (CART). Flock size had a positive correlation with AD, and distance to refuge had a positive correlation with both AD and FID. Juveniles were shyer, with higher FIDs and EDs. Escapes in Helsinki, and by running were shorter. Additionally, in Helsinki, higher pedestrian presence was positively related to AD and ED, flock size with FID, and in commercial land use, birds escaped shorter distances. In Lahti, there was fewer correlations, so that distance to refuge had a positive correlation with AD, juveniles had higher FIDs, and runners had shorter EDs. Built cover had a non-linear relationship with all indicators. Understanding fear is crucial when assessing how species respond to environmental change. At the same time, it offers tools for modulating animal behavior, be it for conservation or non-lethal deterring.
Breeding Common terns Sterna hirundo typically remain at the colony at night, yet nocturnal colony desertion may occur due to predation, nocturnal foraging, or prospecting. We used GPS telemetry data to investigate nocturnal colony attendance and movements of Common terns at multiple freshwater and marine colonies. Across most colonies, nighttime colony attendance was 98%; however, at one marine colony, extremely low attendance occurred (< 0.02%), probably due to nocturnal predation. Terns from the marine colony were also recorded flying slowly over the sea at night, presumably foraging. Nocturnal prospecting of conspecific colonies beyond typical foraging ranges occurred in both sexes. Night-time tracking may help to identify previously unknown colonies and improve monitoring, especially in populations that frequently change breeding locations. For primarily diurnal foragers, including nocturnal tracking in future studies can be used to increase monitoring efficiency, identify threats, and support planning of conservation activities.
In this study, we assessed the possible dual utility of nuptial color patterns in male rainbow darters (Etheostoma caeruleum) in the context of male-male territorial interactions and female mate choice. Using a cohort of wild-caught male E. caeruleum, we conducted simulated territorial contests between pairs of males in the lab. We scored the "winner" and the "loser" of each contest based on behaviors and color changes at the end of each contest. We then performed dichotomous choice trials using the same pairs of males as stimuli and female E. caeruleum as focal subjects. We scored the choice trials based on the female strength of preference. We assigned each male an Elo rating (a relative skill score used in zero-sum contests between pairs of players) in the male-male contests based on wins and losses, and in the choice trials based on female preference across all trials for each male. We evaluated whether success in male-male contests correlated with success in female choice trials. Finally, we measured body area, mean luminance and luminance contrast for each male, and we evaluated whether either variable correlated with success in male-male contests or in female choice trials. We did not find a statistically significant correlation between Elo ratings in the contests and those in the choice trials, although we observed a positive trend in the relationship. Neither body area nor mean luminance was significantly correlated with success in either set of trials, and luminance contrast was positively correlated with success only in the female choice trials. Our findings indicate that the vivid patterns in breeding male E. caeruleum may play a role in female mate choice. This study highlights the importance of evaluating the role of conspicuous nuptial characteristics in both intrasexual and intersexual selection.
Sexual plasticity allows individuals to maximize fitness by adjusting their sex allocation in response to environmental cues. Sequential hermaphroditism, or sex change, is expected to evolve when the reproductive value (i.e. expected future reproductive success) of one sex increases disproportionately with body size. While socially mediated sex change is well documented in adults, less is known about how juveniles respond to social cues during development. Here, we investigated adaptive plasticity in sex allocation in the marine annelid Ophryotrocha puerilis by exposing size- and age-matched juveniles to four social environments: isolation, exposure to adults, and size-matched pairs and triplets. Isolated juveniles changed sex early, whereas nearly all juveniles exposed to adults deferred sex change, suggesting that the presence of adults modulates the timing of sex change. Juveniles in pairs and triplets consistently formed mating pairs through one individual changing sex to female early, supporting our proposed Adaptive Matchmaking Hypothesis that juveniles use conspecific cues to adjust their developmental trajectories and sex allocation. We discuss the adaptive value of such early-life social sensitivity and the potential for sex role preferences in juveniles. This study highlights how social environments shape developmental trajectories in sequential hermaphrodites, beginning earlier in life than previously recognized.
