Flight initiation distance (FID) is an important behavioral metric for assessing an animal's fear level and evaluating the trade-offs in survival strategies under predation risk. Studies have shown that various characteristics of observers - such as clothing, behavior, and gaze direction - can influence avian FID, yet the effect of observer gender on FID remains underexplored. A recent study found that urban birds were less tolerant of women than of men, a consistent observer gender specific pattern in five European countries. In light of this, this study investigated whether the FID of black-headed gulls (Chroicocephalus ridibundus) wintering in tourist areas of Kunming City, Yunnan, southwest China, differed in response to human observers of different genders. Our results revealed no significant difference in the FID measured by male and female observers. The coefficients of variation within both groups were relatively high, and the intra-class correlation coefficients showed significant inter‑observer variations. Due to long‑term exposure to large numbers of tourists with diverse behavioral patterns, the salience of observer gender cues may be attenuated for black-headed gulls. Alternatively, differences among individual observers - potentially including uncontrolled subtle behaviors or appearance features - exert a greater influence on the birds' escape responses than does observer gender. Our study contributed to filling the gap in understanding the effect of observer gender on avian escape behavior.

Testosterone (T) modulates male sexual behavior, partly through actions in the medial preoptic area (mPOA) of the anterior hypothalamus. Although gonadectomy (GDX) rapidly depletes circulating T, the decline in sexual behavior is gradual, taking weeks or months. In some species, prior sexual experience delays this behavioral decay; however, whether this occurs in rats remains unclear. Here, we examined the effects of GDX and prior sexual experience on serum T levels, sexual behavior, and mPOA cellular density in male Wistar rats. Males were assigned to one of two groups: sexually experienced (Stud; n = 6) or naïve (Naïve; n = 6). Stud males underwent five 90-min copulatory sessions with receptive females at 4-day intervals, whereas naïve males were exposed to the chamber alone. All males were then gonadectomized and tested for T levels and sexual behavior at multiple time points from GDX: -1, + 1, + 7, + 30, + 45, and + 110. Sexual motivation was assessed using an olfactory preference test (urine from receptive vs. non-receptive females), and copulatory behavior was evaluated during encounters with receptive females. On GDX + 111, brains were collected for Nissl staining, and mPOA cell counts were quantified. Serum T decreased from approximately 10 ng/mL on GDX -1 to undetectable levels by GDX + 1 in all animals. Olfactory preference for receptive urine was decreased by GDX + 1, but not by + 7. On GDX + 45, stud males showed more genital investigations, mounts, and intromissions, as well as shorter latencies to mount and intromit, than naïve males; however, these differences were no longer evident by GDX + 110. Importantly, mPOA cell density was significantly higher in stud compared to naïve males. Thus, although GDX rapidly eliminates circulating T, prior sexual experience delays the decline of sexual motivation and behavior and is associated with increased cellular density in the mPOA. These findings contribute to understand that sexual experience induces neuroplastic changes in the mPOA that confer resilience to hormonal depletion.

The development of behavioral diversity in juvenile animals is closely linked to their environmental adaptability and survival rate. However, research on development of behavioral diversity in juvenile animals remain limited. From May to August 2021, we surveyed three juvenile black storks (Ciconia nigra), a Class I protected species of China, at Zhangye Heihe National Wetland Nature Reserve in Gansu Province, to explore their behavioral ontogeny. We established their behavioral repertoire, and analyzed rhythms and diversity across developmental stages. The research results revealed that behavioral frequency and diel behavioral rhythms differed significantly across months, while time of day and month both exerted notable influences on behavioral differentiation. All behavioral diversity indices presented distinct monthly changes. Behavioral frequency and behavioral counts increased obviously over time, as did the Shannon-Wiener and Simpson's diversity indices. By contrast, the Berger-Parker and Simpson's dominance indices declined significantly with time, and no obvious correlation was detected between time and Pielou's evenness index. Discriminant analysis confirmed clear behavioral differences among developmental stages, with stable and stage-specific behavioral patterns emerging at different periods. Overall, behavioral development in juvenile black storks follows a clear temporal sequence, with environment-adaptive behaviors being progressively expressed as development proceeds. Behavioral ontogeny advances from simple to complex behaviors and from single to increasingly diverse behavioral repertoires.

Octopuses are keystone species in shallow-water marine ecosystems. While research has focused on predator-prey interactions, the non-neutral interactions between octopuses and fishes have not been well characterized. These range from possible cooperation, kleptoparasitism, and scavenging to occasional predation on unwary fishes. To address this gap, we analyzed video recordings of juvenile Octopus insularis interacting with 10 fish species on Brazilian reefs, compiled an ethogram, and tracked the outcomes of interactions using Lag Sequence Analysis. We observed a total of 101 interactions between octopuses and seven non-territorial fish species and three territorial fish species. Fish territoriality significantly affected the behavior of both fishes and octopuses. The duration of interactions was significantly longer in non-territorial fishes. Interactions with territorial fishes involved faster approaches and higher rates of behavioral change for both animals and were characterized by 'Jabs' and 'Swipes' by fishes, and 'Flinches' and arm 'Arm slaps' by octopuses. Interactions with non-territorial fishes were characterized by 'Follow' and 'Circle' by fishes, and the octopuses continuing their hunt. Lag Sequence Analysis confirmed distinct and predictable behavioral sequences for each interaction type. The presence of territorial fishes also affected octopus body patterning, with the 'Half blotch' - a defensive body pattern - occurring only in interactions with territorial fishes. These results demonstrate that during foraging, octopuses need to navigate a complex set of conflicting interactions.

Parasites and infections are one of the major costs associated with group living and high host density. Although infection threat can influence the behavior of both uninfected and infected individuals, investigations have focused on the responses of uninfected individuals. Here we describe the effects on, and response to, terrestrial snails, Cepaea nemoralis, treated with either a bacterial or viral pathogenic stimulus. Brief exposure of untreated (uninfected) snails to the mucus associated chemical cues of snails acutely treated with either the bacterial cell wall component, lipopolysaccharide (LPS), or the viral mimetic, polyinosinic:polycytidylic acid (Poly I:C), elicited active behavioral avoidance and antinociceptive responses (decreased sensitivity to noxious stimuli). Treated (infected) snails also avoided and displayed antinociceptive responses to the chemical cues of snails with either a simulated bacterial or viral infection; however, each according to their own treatment (infection) status. LPS (bacterial) treated snails avoided the cues of Poly I:C (viral), but not LPS, treated conspecifics, whereas Poly I:C treated snails primarily avoided the mucus associated cues of LPS, but not Poly I:C, treated individuals. These findings show that chemical mediated behavioral avoidance of bacterial and viral threat is affected by both the nature of the infection threat and the infection status of the individual.

Recent cross-species analyses suggest that the different forms of stereotypic behaviour have heterogeneous causal mechanisms. In ungulates, there are indications that some forms of locomotor stereotypy may be linked to social factors. Using the domestic horse as a model species within this clade, we investigated whether individuals displaying the locomotor stereotypy box-walking (n = 6) demonstrated greater responses to a stable mirror, intended to mimic presence of a conspecific, than horses displaying the oral stereotypy crib-biting (n = 5) and non-stereotypic horses (n = 5). After a 24 hr baseline phase, horses were provided with a 1 × 1.5 m stable mirror for 24hrs. This was followed by a 24 hr post-mirror phase. Responses were quantified using measures of behaviour, orientation, and ear and head/neck movements. Box-walking, but not crib-biting, was reduced when the mirror was present, and box-walking remained at this lower level following mirror removal. Box-walkers and non-stereotypic horses spent a greater proportion of time orientated towards the mirror than crib-biters. Box-walkers did not, however, demonstrate increased use of ear or head/neck movements associated with affiliative social behaviours, nor did they exhibit more behaviours indicative of frustration, once the mirror was removed, than other animals. There were, however, other unexpected differences in mirror responses between the stereotypy groups. This study provides an initial indication that stereotypic horses respond differently to mirrors, however a sufficiently powered follow-up, with additional controls, is required to establish if box-walking horses are more socially motivated.

Larval zebrafish have become a cornerstone in neurobehavioral research. However, the reproducibility of zebrafish behavioral studies is often hindered by subtle yet significant variations in experimental parameters. This study systematically investigates how variations in experimental parameters-well geometry; area; plate opacity; genotype; holding temperature; and light intensity-influence larval zebrafish baseline activity and behavioral responses. Using automated behavioral tracking and sample sizes ranging between 73 and 192 larvae/group, we uncovered evident differences in response to changes in these conditions. When assessing geometry and area, larvae in square wells and larger well areas displayed heightened baseline and stimulus-induced behavioral responses; however, relative comparison contradicted these findings indicating smaller areas significantly exaggerated the magnitude of behavioral responses. Clear plates elicited stronger baseline activity and stimulus-driven behaviors. Wild-type fish showed higher behavioral responses than mutants. Temperatures significantly modulated baseline activity and stimulus-induced behavior, while relative comparison analysis revealed increases in stimulus-induced responses across both extremes. Lastly, intermediate light intensities elicited the strongest reactivity, indicating a non-linear relationship between illumination and visual-motor-response behaviors. Our study demonstrates that variation in experimental parameters can alter behavioral outcomes, underscoring the need for standardized zebrafish neurobehavioral assays and for accounting for methodological differences when comparing results. Developing this framework will improve the reliability and interpretability of zebrafish behavioral data.

Rodents exhibit exploratory behaviors, such as rearing and digging, in both novel and familiar environments, which serve to monitor their surroundings. Variations in these exploratory behaviors can serve as sensitive indicators of subtle behavioral effects induced by stressors, including sleep deprivation. Disrupted maternal sleep during gestation has been consistently associated with adverse behavioral outcomes in both the mother and her offspring. Several studies have reported that sleep restriction in late pregnancy increases ultrasonic vocalizations, promotes greater novelty-seeking and risk-taking, and increases activity levels in juvenile and adolescent rodents. However, the neonatal stage remains relatively understudied, despite its critical importance for sensory and motor development. Pregnant BALB/c mice underwent a standardized sleep-deprivation protocol for seven consecutive days (gestational days, GD7-14). Behavioral assessments were conducted in home-cage conditions immediately post-deprivation (GD14), during the recovery phase (GD18), and during the postpartum period (PPD3). Early locomotor behavior was evaluated in offspring of sleep-deprived dams using an open-field test on postnatal day 7 (PND7). Dams exhibited marked increases in mobility, rearing, grid climbing, digging, and spontaneous jumping during the sleep-deprivation days (n = 13 dams) compared with controls (n = 6 dams), with these effects persisting during the recovery period. In the postgestational period, a subset of these dams (n = 5) who delivered viable offspring normalized the frequency of these behaviors, but another subset of sleep-deprived dams who experienced miscarriage (n = 8) persisted with a higher frequency of rearing. Notably, offspring born to sleep-deprived dams showed significant locomotor hyperactivity in an open-field test compared with their controls (n = 15 pups per group). These results highlight that gestational sleep deprivation not only alters maternal exploratory patterns but also programs early offspring locomotor hyperactivity, underscoring its lasting impact on behavioral development.

This study examines differences in response patterns based on associative learning strategies, focusing on goal-tracker (GT) and sign-tracker (ST) profiles in rats. To explore whether maturational processes influence the expression of these phenotypes, Experiment 1 analyzed the distribution of ST and GT profiles across developmental stages (6- and 16-week-old rats). The results indicated a developmental effect on response patterns; younger rats exhibiting a higher prevalence of the GT profile, and no significant sex differences were observed. Experiment 2 assessed the ability of GT and ST animals to suppress their previously expressed behavioral patterns using an omission training procedure. Adult rats demonstrated greater response suppression than adolescent rats. Furthermore, GT profiles showed greater sensitivity to response omission than ST profiles, suggesting that these differences may be related to prefrontal cortex maturation. Sex differences emerged as a crucial factor in adult rats, with female GTs displaying more effective omission than female STs. This finding is particularly important because it may reflect behavioral phenotypes associated with psychiatric disorders, including substance abuse. Taken together, these results highlight how developmental stage and sex influence response profiles in rats, providing translational clinical relevance for understanding core symptoms in neuropsychiatric disorders.

Jellyfish of the genus Aurelia possess a decentralized nervous system and rhopalia that contain basic visual structures, providing a unique opportunity to explore light-driven behavior in the absence of a centralized brain. Despite their anatomical simplicity, little is known about how these animals modulate their motor activity in response to light or whether they exhibit consistent preferences for light or dark environments. In this study, we conducted two behavioral experiments to investigate the light-dependent behaviour in juveniles of Aurelia coerulea. In Experiment 1, we measured pulsation frequency under light and dark conditions as a proxy for motor activity. In Experiment 2, we adapted a scototaxis-based test to assess phototactic preferences in an environment divided into illuminated and dark compartments. Our results show that jellyfish increased pulsation rates under light conditions and spent significantly more time in the illuminated area, suggesting a consistent positive response to light. These findings provide evidence of light-mediated behavior in Aurelia coerulea and contribute to a deeper understanding of how complex sensory-guided behaviors can emerge in organisms without centralized nervous systems.

Conspicuous polymorphisms provide natural tests of mechanisms maintaining behavioral and underlying genetic variation. Cognition has received relatively little attention in color-polymorphic systems. We used a melanin-based polymorphism in the eastern mosquitofish (Gambusia holbrooki) to ask whether performance in a detour task differs between morphs. Melanic males (N = 38) solved the task more often than silver males (N = 37) and had a 1.59-fold higher estimated solution rate, although effect sizes were modest and statistical support was limited. These results suggest that processes associated with detour-task performance may represent an underappreciated axis of morph divergence with a potential role in the maintenance of melanin-based polymorphism.

The estrous cycle of female mammals does not only cause regular changes in steroid hormone concentrations but can also influence behavior and hence (social) life. A valuable model organism to study such effects is the guinea pig: its long 16-day estrous cycle with an active luteal phase represents a perfect opportunity to investigate the estrous cycle in detail, but information on estrous cycle effects is scarce. This study investigated the proestrus/estrus and diestrus phases of two consecutive cycles in twelve socially housed female guinea pigs. Following cycle monitoring, sociopositive and aggressive behavior, general activity patterns, anxiety-like behavior, and saliva cortisol concentrations were investigated on three days around estrus (day -1, day 0 = estrus, day 1) and in diestrus (day 7, day 8, day 9) each. Aggressive behavior significantly increased on day 0 (estrus) and the guinea pigs spent less time in the shelters and more time feeding on day 9 compared to day 7 in diestrus. Cortisol concentrations were increased around the time of estrus versus diestrus and body mass was decreased on day 0. None of the behavioral parameters affected cortisol concentrations considerably, except for a weak negative effect of the time spent feeding. This study demonstrates that the estrous cycle exerts an effect not only on physiological parameters but also on the behavior of group-living female guinea pigs. This represents an important starting point for future research and highlights stronger consideration of the estrous cycle when investigating (social) behavior and physiology in female guinea pigs.

Animal models remain essential in translational research, particularly in neuroscience, where behavioral assessments are used to investigate brain function and disease mechanisms. However, conventional statistical approaches, focused on frequencies, durations, and correlations, provide limited insight into the temporal organization and dependency structure of behavior. These methods treat behaviors as isolated or aggregated events, often overlooking the sequential, hierarchical, and dynamic nature of behavioral expression. This perspective advocates the adoption of analytical frameworks that integrate pattern-oriented and time-series dependency inference approaches. Tools such as THEME enable the detection of non-random, temporally structured behavioral sequences (T-patterns), revealing how behaviors are hierarchically organized over time. To further incorporate the possibility of assessing directed dependencies in behavioral sequences, tools such as Tigramite can be useful. Under specific assumptions, this tool allows the estimation of time-lagged, confounder-controlled, conditionally independent relationships between behaviors, representing them as dynamic interactions established over time. By combining these approaches, researchers can move beyond descriptive analyses toward generating hypotheses about the temporal organization and interdependence of behavioral events. Animal models of conditions such as drug addiction, autism spectrum disorder, anxiety disorders, and Alzheimer's disease, among others, in which traditional measures incompletely capture the richness of behavioral interactions, could benefit from this approach. Time-series inference methods may help identify candidate behavioral predictors and generate testable hypotheses about underlying pathophysiology. Overall, adopting this integrative, time-resolved analytical strategy may enable more comprehensive, reproducible, and biologically meaningful insights from animal models.

Utilizing shelters and living in groups are key anti-predator strategies among fish. Species that have evolved under different ecological conditions may exhibit distinct escape behaviors, reflecting variations in cognitive ability and social information transfer. This study investigate3-fishesd how group size and visual landmarks shape collective escape behavior in fish species from divergent flow habitats: the demasoni cichlid (Chindongo demasoni, preferring stagnant water), zebrafish (Danio rerio, preferring slow-flowing water), and qingbo (Spinibarbus sinensis, preferring fast-flowing water). For each species, 1080 individuals were tested in a between-subjects design, distributed into groups of 3 or 6 with or without landmarks. Using a Y-maze, we assessed the effects of shoal size (3 vs. 6) and the presence of visual landmarks on escape accuracy and latency to enter a shelter arm following brief environmental exploration and a simulated predation stimulus. Results indicated that distinct anti-predator strategies were shaped by species-specific cognitive profiles. The demasoni cichlid exhibited the most cognitively flexible behavior, including rapid decision making and a landmark-dependent shift from passive sheltering to active patrolling. In contrast, zebrafish responded with a generalized increase in shelter use, whereas qingbo behavior was strongly mediated by group competition. The benefits of larger group size and landmark presence were context-dependent, challenging the universal applicability of collective intelligence theory. Our findings demonstrate that anti-predator decision making is deeply rooted in species' evolutionary histories, providing crucial insights for developing conservation strategies that account for behavioral adaptation and cognitive ecology.