The selection and expression of conspicuous colorations in animals is often related to anti-predation strategies and sociosexual communication. The giant river prawn, Macrobrachium rosenbergii (de Man, 1879) is a species with three male morphotypes that vary in claws' coloration and the size of the animals. It has been suggested that male reproductive quality might be associated to their coloration, but evidence is still conflicting. In addition, a possible communication function of orange patches, that occupies a large portion of egg-bearing females' cephalothorax, has never been investigated before. For that matter, in this study, we evaluated the importance of visual cues for reproductive decision making by males and females of the giant river prawn. Through two-choice discrimination experiments, we verified whether: 1) females would be equally attracted to the presence of males expressing different claw colorations and body sizes; 2) female reproductive status and body size would influence males' decision making. Under the tested experimental conditions, females predominantly chose larger over smaller males, while males showed no significant preference for any kind of female. It is possible that body size is one of the cues that females use to identify males' morphotype. The choice of larger males could provide greater protection for females against harassment by other males. Further studies should employ visual cues in combination with chemical ones for a better understanding of mate choice in this species.

Visuospatial working memory (VSWM) is crucial for navigating complex environments and is known to decline with ageing. The Free-Movement Pattern (FMP) Y-maze, used in animal studies, provides a robust paradigm for assessing VSWM via analyses of individual differences in repeated alternating sequences of left (L) and right (R) responses (LRLR, etc.), the predominant search pattern in many species. Previous human studies have used a honeycomb-shaped maze, designed for continuous search and trajectory-based navigation, and have shown ageing-related decline in performance of alternating responses. To date, there has been no examination of responses in the closed Y-maze in humans, faithfully replicating the discrete arm entry conditions of animal experiments. Experiment 1 replicated results observed in the honeycomb Y-maze: younger participants (18-40 years) displayed higher levels of alternating turns (LRLR/RLRL), while older participants (70+ years) exhibited predominantly sequential repetitive responses (i.e. LLLL/RRRR). Experiment 2 demonstrated that alternations reflect VSWM. Specifically, there was a significant correlation between proportion of alternating responses and higher scores on the digital Corsi test, a validated measure of VSWM. When alternating responses were reinforced in Experiment 3, older participants still alternated less and repeated more than younger participants. These findings suggest that age-related declines in VSWM underpin the repetitive search patterns observed in older adults. By faithfully replicating the conditions of animal studies, the closed FMP Y-maze offers a simple, scalable tool for assessing VSWM in humans. Its design is particularly suited for gamification, enhancing motivation, reducing stress, and personalizing interventions to improve performance in older populations.

Predation risk can influence behavioral decisions of animals in various ways. Prey animals have the opportunity to choose antipredation behaviors and escape strategies only by quickly and accurately identifying predators. As precocial birds, domestic chickens (Gallus gallus domesticus) have no adaptation period after hatching and must immediately survive under predation risk. They possess a strong ability to identify threats through vocalizations. To explore whether domestic chickens have innate predator recognition ability and whether the antipredation behavior of breeding chickens is stronger than that of non-breeding chickens. We tested the antipredation behaviors of three types of flocks (non-breeding chickens; hen with chicks; isolated chicks) of domestic chickens in response to sparrowhawk (Accipiter nisus) calls using playback experiments, while Oriental turtle dove (Streptopelia orientalis) calls were used as a control. We found that breeding hens are significantly more vigilant than non-breeding chickens. We also found that although isolated chicks can exhibit antipredator behavior, they cannot accurately identify the calls of predators and non-predators. Therefore, it can be concluded that domestic chickens exhibit varying degrees of vigilance towards predator calls at different stages of their life history. Reproductive costs can lead to increased vigilance in domestic chickens. The accurate identification of predators by domestic chickens is not innate, but gradually formed over time.

This study investigated the impact of engaging in concurrent behaviors on the emergence of untrained stimulus-stimulus relations, specifically examining interruptions, accuracy, and reaction times during test. Six participants completed a computerized matching-to-sample task under three conditions: a baseline condition, a singing condition hypothesized to be incompatible with covert verbal behavior, and a foot tapping condition hypothesized to be compatible with covert verbal behavior. The tempo was kept consistent across both singing and foot tapping tasks. Results indicated a higher average number of interruptions in the foot tapping condition compared to the singing condition. Accuracy and reaction time results varied between participants, indicating individual differences in the impact of the concurrent behaviors. Some participants showed decreased accuracy and increased reaction times during the foot tapping condition, while others demonstrated consistent performance across both conditions. These findings highlight the potential role of response fluency in the execution of concurrent tasks and the influence of verbal mediation on complex behaviors. These insights have implications for the design of experimental tasks and the interpretation of results in studies involving complex behavior and concurrent tasks.

Tourism, as an important manifestation of urbanization, is becoming increasingly popular. Although it offers numerous advantages for the local community, it also exerts a multifaceted impact on local wildlife. Previous research on the effects of tourism has mainly focused on protected areas or tourist spots, rarely considering the surrounding non-tourist attraction areas. Therefore, exploring the behavioral differences of wildlife in response to different levels of human disturbance in areas of tourist and non-tourist attraction will contribute to a more comprehensive understanding of the impact of tourism activities on animals. This study compared the differences in the flight initiation distance (FID) of Eurasian tree sparrows (Passer montanus) between areas of tourist attraction (Xijiang Miao Village and Zhaoxing Dong Village) and non-tourist attraction (surrounding villages) in Guizhou Province, southwestern China. We found that Eurasian tree sparrows in areas of tourist attraction exhibited shorter FIDs than those in areas of non-tourist attraction, suggesting that Eurasian tree sparrows inhabiting areas with higher levels of human disturbance demonstrate a greater ability to adapt to anthropogenic disturbance. Moreover, the FID of Eurasian tree sparrows was less influenced by flock size than by tourist attraction category. It highlights the notable impact of human activities on wildlife, contributing to the scientific management and protection of birds in urban environments.

Neophobia and exploratory behavior are personality traits through which organisms evaluate and respond to environment changes by adjusting their behavior. The Kelp Gull (Larus dominicanus) is a generalist seabird that consumes a wide variety of prey. Neophobia levels and exploratory behavior in novel circumstances were analyzed in urban adult (n = 13) and immature (n = 15) Kelp Gulls captured in the landfill of Mar del Plata city. These personality traits were not significantly affected by the age of the bird. Longer feeding latencies were observed in presence of novel objects, and neophobia levels were higher in the presence of a transparent box. The exploratory events were brief and influenced by the physical properties of the objects; gulls favored complex and yellow objects. Higher neophobia levels were associated with a longer time to start the exploration and spending less time investigating the objects. Exposure to an urban environment can modulate the novelty response, partially explaining lack of difference in neophobia levels and exploratory behavior between ages, as well as the apparent absence of intrinsic attraction to unfamiliar objects when not associated with a food source. Furthermore, in relation to complex objects, unfamiliar objects likely offer richer information, driving gulls' exploratory preference.

Zoo animals are regularly exposed to a plethora of sensorial stimuli beyond their control, which can adversely impact their behaviour and welfare, including unfamiliar faces, excessive noise and intrusive visitor interaction. Zoos have implemented various measures, such as enrichments and regulation of visitor behaviour, to mitigate these effects. However, guided tours have not been used to simultaneously control visitor behaviour and maintain animal welfare. In this study, we investigated how visitors influence the behaviour of two non-human primate species: white-handed gibbons (Hylobates lar) and capuchin monkeys (Sapajus apella), by observing primate behaviour and visitor noise and behaviour under guided and self-guided tour conditions. The main focus was to assess visitor impact on animal welfare and investigate whether guided tours helped regulate visitors' unwanted noise and behaviour. Observational data on several behaviours were obtained through instantaneous sampling intervals lasting 15-minutes each. Results indicate that in the gibbons' enclosure, guided tours, compared to self-guided tours, were associated with lower noise levels (mean reduction of 3.0 dB) and reduced self-grooming frequencies. Conversely, capuchin monkeys exhibited similar behavioural responses between tour types, likely influenced by the presence of an infant born during the study. Although results varied, they suggest guided tours might be associated to reduced visitor noise and may provide a familiar presence for the animals, due to the presence of a guide, which could potentially influence welfare outcomes. However, evidence of enhanced welfare remains inconclusive. Furthermore, integrating guided tours as educational and conservation initiatives could effectively engage visitors and ensure zoo animal welfare.

Female sexual behavior is a naturally rewarding activity that plays an important role in reproduction and species survival. For female rats, regulating the timing of sexual interactions is essential for optimizing mating satisfaction and enhancing the physiological conditions needed for successful fertilization. So far, traditional research on female sexual behavior has relied on a limited set of behavioral parameters, which has certain shortcomings. To address this, our study aimed to develop a more detailed behavioral framework for assessing temporal copulatory patterns in female rats. We compared fully receptive females and less-receptive females, while also investigating the effects of (R)-(+)-8-OH-DPAT, a 5-HT receptor agonist known for its inhibitory impact on female sexual behavior. Additionally, we examined how sexual experience and pacing conditions influence these copulatory patterns. Our results revealed that female rats engage in structured patterns of sexual bouts and time-outs, with higher receptivity leading to more sexual bouts and shorter time-outs. This suggests that sexual bouts can be viewed as an indicator of copulatory speed, while time-outs reflect motivation to continue mating. Sexual experience did not enhance sexual performance but did result in females receiving more copulatory events from males. Lastly, we found that the conditions under which mating occurs (paced vs. non-paced) may not significantly impact copulatory behavior in fully-receptive females, but could be more relevant for less-receptive females. Despite this, paced mating conditions remain preferable for studying female sexual behavior.

Scent marking through urine spraying is known to aid mate selection, territory marking and chemical communication in terrestrial, but not in aquatic mammals. We quantify an unusual aerial urination behaviour in botos (Inia geoffrensis) and discuss its potential functions. Between 2014 and 2018, we conducted land-based behavioural surveys on wild botos in central Brazil, recording the sequence, duration and social context of aerial urination. Aerial urination starts with a boto slowly positioning itself upside down, exposing its penis above water, and ejecting a stream of urine into the air. When a 'receiver' male is present, it either approaches the urine stream with its rostrum (sometimes pursuing it) or stays where the stream contacts the water. We recorded 36 aerial urination events during 218.9 observation hours, with 67 % occurring in the presence of receivers. The events were short (11.6 ± 9.6 SD s), highly variable (range 1-41 s) and involved only males-urinators and receivers. We hypothesize that the bristles on botos' rostrums can serve a chemical sensory role (haptosense) in detecting urine streams and that aerial urination, often occurring in the presence of other males, serves social or communicative functions beyond the physiological need for waste elimination.

The marginal value theorem (MVT) predicts that optimal foragers leave a patch when the instantaneous gain rate decreases to the average long-term gain rate. However, various animals systematically deviate from this optimum by staying too long or overharvesting relative to this optimum. We hypothesised that animals do not represent their optimal stay time but instead determine their departure point probabilistically. To test this hypothesis, we conducted behavioural experiments and modelling using chicks. The chicks ran on a treadmill with feeders on both sides, and their travel time to the feeder was experimentally controlled. As predicted by the MVT, the chicks stayed longer at the feeder when forced to run more. However, they stayed even longer than predicted by the MVT. Therefore, we constructed and compared stochastic decision-making models with the MVT-based model. The stochastic models explained the chicks' behaviour better than the MVT-based model. These results suggest that chicks leave probabilistically based on their immediate foraging history rather than representing an optimal stay time.

Activity budget investigations are necessary to understand how individuals within a group manage their daily activities, thus providing insights into the social dynamics of a species. Our objective was to explore and describe the behavioral activities within a group of managed care killer whales. From 261 hours of coded surface video collected from April 2022 to January 2023, we scan-sampled day-time hours to examine eight behavioral categories exhibited by 8-9 killer whales bimonthly. Minimal sex differences were found within each behavioral category across month and hour block. Females exhibited significantly more attention to trainers and rubbing on the environment than males. Individual variability was documented for all behavioral categories. The youngest male showed the most (43 % of scans) proximity and social interactions with conspecifics whereas all adults, both females and males, showed similar levels of social behavior. Three adult females and one adult male spent about a third of all scans observing their trainer(s) as they moved around the habitat. This observational behavior has been described in other delphinids as anticipatory behavior indicating a willingness to participate in future interactions with their trainers whether food rewards were available or not, and has been confirmed to represent a state of positive well-being. All killer whales actively engaged with peers and their environment in about 40 % of the documented scans. These findings are similar in degree to that observed in various other delphinid populations and support the interpretation that this killer whale group is in receive of positive welfare, displaying normal levels of social and individual behaviors for this species. Our results add to the growing body of knowledge about how killer whales manage their actions, both with conspecifics and their environment, across different social settings given their surroundings.

Black-capped chickadee (Poecile atricapillus) vocalisations remain plastic throughout their lifespans. Although fledglings employ vocal plasticity to refine their vocalisations through the use of tutor mimicry, adults employ vocal plasticity to create unique population dialects. Vocal convergence is one mechanism by which flockmates' vocalisations become increasingly similar to each other and distinct from the calls of other flocks. Chick-a-dee call plasticity via vocal convergence has been observed in wild and group aviary-housed laboratory chickadee flocks. Our study aimed to answer whether individually-housed laboratory chickadee colonies possess unique vocal dialects similar to wild populations. A group of six individually-housed chickadees from two laboratory colony rooms were introduced to a new experimental colony room. Calls were recorded at baseline and weekly thereafter for 8 weeks. We then conducted an operant conditioning study using a Go/No-go paradigm with birds not included in our experimental-colony, to determine whether black-capped chickadees could discriminate between calls from the two laboratory colonies, using four experimental-colony birds' baseline pre-assembly recordings as discriminative stimuli. We tested generalisation using novel, pre-assembly calls from the remaining two experimental-colony birds. Next, we tested whether chickadees perceived a change in calls following experimental-colony assembly, putatively indicative of vocal plasticity, marked by a decrease in discrimination accuracy. Chickadees successfully discriminated reinforced from non-reinforced calls using pre-assembly calls, but did not generalise this learning when later presented with novel pre-assembly calls from new birds. We posit that instead of employing colony-based discrimination, chickadees relied on individual-based discrimination. Chickadees were also not able to generalise their learning when presented with post-assembly calls from the same birds. Our findings suggest that chickadees were able to discriminate between individuals', but not colonies', chick-a-dee calls in an operant-conditioning procedure. Furthermore, chickadees can perceive differences in pre-versus-post assembly calls. Taken together, these findings suggest that group and individual identity information may be correlated, as post-assembly vocal plasticity impeded individual discrimination.

Virtual environment software is increasingly being employed as a non-invasive method in primate cognition research. Familiar and novel stimuli can be presented in new ways, opening the door to studying aspects of cognition in captivity which previously may not have been feasible. Despite the increased complexity of visual input compared to more traditional computerised studies, several groups of captive primates have now been trained to navigate virtual three-dimensional environments. Here, we outline a method for training primates to use a computerised virtual foraging task presented on a touchscreen. We document how to tailor this method to groups facing different training challenges. We present data from three groups: touchscreen-experienced chimpanzees (Pan troglodytes), touchscreen-naïve orang-utans (Pongo abelii), and chimpanzees tested in a group setting. Subjects from all groups mastered basic navigation challenges with relative ease (some in as little as 16 days), setting them up for systematic studies of primate cognition within virtual environments. The training method we present is flexible, yet structured, and we encourage other researchers to adapt it to implement virtual environment research with more individuals and across more species.

One of the simplest forms of behavior, operant behavior, appears fundamentally prospective, implying potential similarity to 'sophisticated' prospective behaviors like planning in terms of underlying mechanisms. But differences between paradigms for studying behavior resulting from 'simple' versus 'sophisticated' mechanisms prevent true comparison of underlying mechanisms. To aid development of an operant paradigm with more similarity to 'sophisticated' prospective paradigms, we replicated and extended Cowie and Davison's (2021) investing task. Pigeons were required to emit an investing response to ensure food at a different time and different response location. We asked if investing depended on whether the behavior was a single, discrete key peck (typical in operant paradigms) or an extended sequence of pecks (echoing behaviors in planning paradigms), and whether facilitative effects of an immediate stimulus change persisted when the stimulus change no longer occurred. Pigeons invested successfully whether investing required one or more responses, and for extended investing responses, performance did not worsen significantly with increasing response requirements. Experience investing with an immediate stimulus change did not enhance subsequent investing without the stimulus change. Findings show simple learning mechanisms can support extended activities with no immediate consequences. Further, they support the investing paradigm as a potential tool for investigations of overlap in mechanisms controlling 'simple' and 'sophisticated' behavior.

To cope with heat stress, storks wet their legs by excreting on them, known as urohidrosis, and perform wing-spreading in which the wings are half extended in the form of an inverted triangle. While several studies have highlighted the role of urohidrosis as an important cooling mechanism and suggested a possible thermoregulatory function of wing-spreading, sex-based comparisons and trends of these behaviours throughout the breeding season remain unexplored. Here we explore thermoregulation in a wild population of Painted Storks (Mycteria leucocephala) nesting in the National Zoological Park, Delhi, India, through the non-invasive videography technique. Temperature, humidity and wind speed significantly influenced both urohidrosis and wing-spreading behaviours. Male storks exhibited higher rates of urohidrosis and spend more time wing-spreading compared to females. Seasonal and diurnal differences were observed with more urohidrosis and wing-spreading during the hottest hours of the day and early part of the nesting season in August-September. The rate of both behaviours declined as the nesting season progressed till November when ambient temperatures dropped.

Crustaceans are increasingly used as research subjects in experiments investigating learning in invertebrates. While many of these species may be useful models it is essential to document the presence or absence of behavioral laterality, especially considering the long-held belief that functional lateralization was unique to humans or other vertebrate species. Neglecting this fundamental step weakens the applicability of results and may unnecessarily complicate experimental design. Amphipods (Gammarus pseudolimnaeus) may be a useful invertebrate for studying simple discriminations or escape behavior, but research on their potential behavioral laterality is absent. The current study investigated whether amphipods demonstrate a left-right bias when navigating an aquatic T-maze by placing them in the maze and recording their choices across multiple trials. Our results suggested that amphipods do not show a strong left-right bias during initial navigation of an aquatic T-maze. These findings may encourage other researchers to test invertebrates for behavioral laterality, utilize amphipods in studies of simple forms of learning, and potentially simplify future experimental design.

Aposematism is a widespread defense mechanism in animals. Anuran amphibians are known for their extensive repertoire of defenses, especially in the adult stage. Color-based mechanisms are particularly common in this group, although their use during the larval stage is still understudied. The hypothesis of aposematism in tadpoles has been suggested for several species that present conspicuous coloration and unpalatability. Tadpoles of some bufonid toads have been considered aposematic for decades, as they have a conspicuous black color, are unpalatable, and form aggregations that make them even more visible. However, few empirical studies have tested aposematism in these larvae against visually oriented predators, such as birds. In this paper, we tested whether the uniform black coloration acts as an aposematic signal in anuran larvae. The research was conducted through field predation experiments using artificial replicas of tadpoles of different colors (brown, gray, and black). The survival of black replicas was significantly higher than that of control groups, supporting the aposematism hypothesis. Given that the replicas varied only in color, we conclude that the differential attacks among treatments were carried out by visually oriented predators, probably birds, that had learned to recognize and avoid black tadpoles.

Population density in experimental animals is a crucial factor in maintaining the wellbeing of the organisms. Inadequate housing conditions can compromise the validity and reliability of research results, making comparisons between studies difficult. In sociable species such as zebrafish (Danio rerio), which are housed in groups, overcrowding or undercrowding represents a variable that needs to be considered. In this study, we evaluated the effects of housing at different densities for different exposure times on the anxiety response measured in the Plus Maze with Ramp test in zebrafish. The subjects (144) were divided into three large groups according to the housing time (1, 7, and 30 days). Each group was divided into six subgroups based on the density of the fish (0.25, 0.5, 1, 2, 4, 6 fish/liter, n = 8) and housed in a 4-liter aquarium. After the housing conditions, each animal was tested individually in the PMR. Time and housing density altered the exploratory behavior of zebrafish. Increased housing time reduced the time spent in the ramp arms, with groups kept for 30 days spending less time in this compartment. Density increased the time spent in the flat arms in groups with 2 and 6 fish/liter and, conversely, reduced the exploration of the ramp arms. Isolation, on the other hand, increased the exploration of the ramp arms, indicating an anxiolytic effect. In this study, we demonstrate that housing conditions can act as low-intensity chronic stressors that alter anxiety-like behavior in zebrafish when tested in the PMR protocol.

Birds have evolved a variety of antipredator strategies, which have been extensively studied during day-time. Yet, how diurnal birds directly respond to nocturnal predation threats remains largely elusive, despite that predation risk can be high during both night- and day-time. One form of antipredator behaviour found in several tit species when confronted with a predator at the nest is the hissing display. As for many forms of antipredator behaviour, studies on hissing displays have so far focussed on the day-time. Here, we exposed cavity-nesting free-living female great tits (Parus major) to simulated predator intrusions inside their nest box during both night- and day-time. We showed that 28 % of females uttered at least one hissing call during night-time, while the occurrence of hissing calls was higher during day-time (84 %). Hissing females at night, compared to non-hissing females, produced more hissing calls during day-time, providing evidence for individual cross-context consistency. Night-time hissing behaviour did not predict lay date, clutch size, breeding or nest success, indicating the absence of consequences in terms of current reproduction. Together, we reveal the hitherto undescribed occurrence of hissing displays at night in a cavity-nesting bird, while simultaneously strengthening the evidence for the existence of hissing behavioural types.

Research with nonhuman animals and children suggests reinforcer control is prospective; that is, behaviour is organised according to the likely future, as extrapolated from past experience. The present experiment extended this work to adult choice, and also explored the effects of individual differences in past, present, and future time-orientation on reinforcer control. Participants (N = 163) responded in a concurrent schedule in which the probability of a reinforcer at the same location as the previous reinforcer varied across conditions. Choice tracked these probabilities, albeit imperfectly, indicating that reinforcers controlled behaviour prospectively. Deviations in choice from reinforcer probabilities were well-captured by a quantitative model assuming that such deviations arise because reinforcers are misallocated to the wrong alternative and because of biases towards one alternative. This replicates previous findings in pigeons and children, hence demonstrating the cross-species generality and developmental continuity of prospective reinforcer control. Individual differences in time orientation appeared not to influence reinforcer control, although further work is needed to explore the conditions under which time orientation modulates prospective reinforcer control.

Social groups repeatedly solving a complex task can improve their collective performance. To study the mechanisms of collective improvement, we tested the effect of experience on collective decision-making using acorn ants (Temnothorax ambiguus). During a six-emigration training phase, colonies in the choice treatment gained experience choosing to move into one of two nests varying in quality, while colonies in the no-choice treatment had only a single available nest. Both treatments were tested in a subsequent test with two nests of varying quality. We found that experience improved decision-making speed, regardless of treatment. We also found that colonies of the choice treatment were more proficient by carrying a larger proportion of individuals directly into the better-quality nest. However, there was no steady improvement in proficiency throughout their training. Using social network analysis, we quantified changes in group performance over successive emigrations. We found that network density, our measure for social connectedness, and the coefficient of variation of out-strength distribution, our measure for workload distribution, did not differ between treatments and remained stable over successive emigrations. We conclude that collective experience with decision-making may improve subsequent group performance, but the mechanisms of improvement remain unclear. Further research on decision-making in house-hunting ants will advance our understanding of the mechanisms underpinning collective improvement.