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Ethology

Wiley

Preprints posted in the last 30 days, ranked by how well they match Ethology's content profile, based on 18 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

1
No evidence of sentinel behaviour in a highly social bird based on an artificial set-up

Marmelo, M.; Silva, L.; Ferreira, A.; Doutrelant, C.; Covas, R.

2026-03-24 animal behavior and cognition 10.64898/2026.03.17.712373 medRxiv
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Sentinel behaviour occurs when individuals use raised positions to scan for predators while the rest of the group forages. Here, we investigated whether a colonial cooperatively breeding species that forages in large groups, the sociable weaver, Philetairus socius, displays sentinel behaviour. This behaviour has been reported in species with similar ecology, behaviour and foraging habits, (e.g. ground foraging in open habitats where aerial predators are common) and, hence, we expected that it could occur in sociable weavers. On the other hand, sentinel behaviour appears to be less common in species that live in very large groups. We used an experimental set-up consisting of an artificial feeding station and perches to assess occurrence of sentinel related behaviours: (i) perching events > 30s on an elevated position, (ii) head-movements and (iii) alarm calling. Birds were seldom observed perching while others fed, and those that did, perched for periods that were too short to be considered as sentinel behaviour (less than 5s on average). Our results suggest that this behaviour is uncommon or even absent in sociable weavers. We discuss whether other factors such as foraging in very large groups, or interspecific foraging associations might make sentinel behaviour less important in this species.

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Energetics and behavior during predation in wild, schooling white mullet (Mugil curema)

Mukherjee, I.; Liao, J.

2026-04-06 animal behavior and cognition 10.64898/2026.04.02.716113 medRxiv
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Although predation is a major driver of group living across taxa and the antipredator benefits of grouping are well established, the energetic costs experienced by groups under predation remain largely unexplored. In the current study, we use wild, white mullet (Mugil curema, Valenciennes 1836), to provide the first real-time quantification of the energetic cost of escape in schooling fish using intermittent, closed-loop respirometry. We found that small groups exposed to predators showed a 53.8% increase in their organismal metabolic rate (MO2) as compared to groups without predator exposure. When we evaluated antipredator behaviors such as escape response, group cohesion, and displacement of the group centroid, we found a positive correlation to energetic costs. We then investigated whether escape responses are socially modulated by comparing the energetic costs of escape across solitary individuals, solitary individuals with visual access to a group, and groups. We found that escape frequency and energetic costs to predation were comparable across social contexts, indicating that escape may be an intrinsic survival response independent of cues from group members. Furthermore, we found that fish exposed to predators showed markedly reduced feeding, suggesting that predation constrains energy acquisition in addition to imposing direct energetic costs. Our results provide the first direct quantification of the energetic costs of escape in a schooling fish, offering new insights into the physiological trade-offs underlying collective antipredator defenses.

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Context-Dependent Reactive Antipredator Behavior of Chacma Baboons (Papio ursinus) Amidst Predator Recovery

Van Cuylenborg, S. M.; Wright, N. S.; Palmer, M. S.; Carvalho, S.; Gaynor, K. M.

2026-04-08 animal behavior and cognition 10.64898/2026.04.05.716544 medRxiv
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Predation is a driving force in the ecology and evolution of prey, and primates exhibit diverse anti-predator strategies for minimizing risk. Because these behaviors can be costly, individuals must balance costs and benefits when responding to perceived threats. The cognitive capacity and behavioral plasticity of baboons make them an ideal taxon for studying the context-dependent variation in anti-predator strategies. Here, we used an autonomous, motion-activated playback experiment to study the behavioral responses of chacma baboons (Papio ursinus griseipes) to simulated predator encounters in Gorongosa National Park, Mozambique. We compared responses in 2021, when predator densities were relatively low, to responses in 2024, after predation increased due to lion (Panthera leo) population recovery and African wild dog (Lycaon pictus) reintroduction. We compared flight and vigilance responses to vocalizations of these common predators with responses to leopard (Panthera pardus), historically a key predator; spotted hyena (Crocuta crocuta), a rare predator; and cheetah (Acinonyx jubatus), absent historically and currently. We also assessed how responses varied with habitat, age-sex class, presence of offspring, and group size. Across 916 predator playbacks, baboons fled in 19% and displayed vigilance in 71% of trials. When predator density was higher, baboons displayed weakened antipredator responses, consistent with the risk allocation hypothesis. Baboons were more likely to flee in response to lion and wild dog cues. Juveniles fled more frequently than other demographic classes, while adult females with offspring were more vigilant. Overall, responses were highly heterogeneous, reflecting the substantial intraspecific variation and behavioral flexibility characteristic of baboons.

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Reef fish escape responses selectively match predator attack speeds

Neven, S. L.; Faber, L.; Martin, B.

2026-03-24 animal behavior and cognition 10.64898/2026.03.21.713327 medRxiv
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Animals must continually balance foraging with the risk of predation. In complex natural environments, this means quickly distinguishing between threats and harmless situations. We investigated how site-associated coral reef fishes decide to escape in response to visual cues mimicking predator attacks, using controlled underwater presentations of looming stimuli at varying speeds. We measured escape responses across species and social contexts, comparing them to predator attack speeds observed in the same habitat. Escape responses were highly sensitive to the speed of the looming stimulus, with no responses occurring at low speeds. The speeds triggering escape matched those of predator attacks, whereas cruising swim speeds never triggered a response. Species employed distinct antipredator strategies: Brown Chromis foraged away from shelter with high responsiveness, whereas Bicolor Damselfish remained shelter-dependent with lower escape propensities. Contrary to expectations, the social factors did not affect responses in this study. These findings demonstrate that reef fish are highly sensitive to the approach speed of objects, with species-specific strategies further shaping behaviors. By combining realistic visual threats with natural predator attack data, this study offers insight into how animals make escape decisions in complex, real-world environments.

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Using activity data to estimate brown bear den exit and entry dates

Brault, B.; Clermont, J.; Zedrosser, A.; Friebe, A.; Kindberg, J.; Pelletier, F.

2026-04-01 animal behavior and cognition 10.64898/2026.03.30.715338 medRxiv
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BackgroundIn hibernating mammals, the timing of den entry and exit reflects complex interactions among environment, physiology, and energetic constraints, with consequences for fitness. Consequently, shifts in denning phenology can affect population dynamics, particularly under climate change. Reliable estimation of denning timing is therefore critical, yet current methods often rely on GPS-derived movement data, limited by coarse sampling intervals, detection issues, and the inability to distinguish true inactivity from active presence at the den site. In this study, we developed and apply a method to estimate denning phenology in a brown bear population in south-central Sweden using accelerometer-derived activity data. Our approach employs adaptive, individual-specific thresholds to account for variation in baseline activity across bears, focusing on day-to-day changes to identify the start and end of inactivity periods. This method allows flexible and reproducible detection of den entry and exit dates, overcoming limitations associated with fixed thresholds and small sample sizes. ResultsWe compared activity-based estimates with GPS-derived den occupancy and examined variation in denning behavior across demographic groups. Analyzing 388 bear-winters, the method successfully identified inactivity periods in 360 cases. The method failed to identify clear start and end dates of hibernation for 28 (7%) bear-winters, which were characterized by unusually high or low daily activity levels at the boundaries of the inactivity period. Den site occupancy ranged from September 5 to June 2, with durations of 112-260 days, whereas inactivity periods detected from activity data extended from September 6 to May 13, lasting 83-217 days. Our comparison of activity-based and GPS-based methods indicates that bears may arrive at the den site several weeks before the onset of inactivity, with timing varying among demographic groups. ConclusionWe show that activity-based analysis provides a robust framework for estimating denning phenology, distinguishing actual inactivity from site presence, and improving understanding of the timing and variability of bear denning behavior. Applying an individual-level activity-based method improves accuracy in assessing ecological mechanisms underlying hibernation in bears and other hibernators, while also enhancing interpretation of environmental drivers and providing a reliable tool to monitor phenological shifts in response to climate change.

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Which senses do wild vervet monkeys (Chlorocebus pygerythrus) use for evaluating potential food items?

Ondina Ferreira da Silva Teixeira, C.; van de Waal, E.; Laska, M.; Motes-Rodrigo, A.

2026-03-30 animal behavior and cognition 10.64898/2026.03.27.714682 medRxiv
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Traditionally, primates have been considered primarily visual animals. However, studies across a variety of taxa suggest that, in the context of food evaluation, the reliance on this sense might be more nuanced that previously thought, with dietary specialization and food item properties leading to differences in sensory prioritization. We performed a field-based study assessing the use of sensory cues during food evaluation as well as food-related behaviours such as muzzle contact in two mixed-sex groups of wild vervet monkeys including three age classes over a period of five months (nmonkeys = 44). Using a total of 18868 food evaluation observations collected over 44 hours of focal follows, we found that vervets mainly relied on their sense of vision when evaluating food (96.8% of all instances). Sensory usage varied according to food category and sex differences were only observed in the use of smell for a subset of these. Juveniles initiated muzzle contact and used tactile inspection more often than adults whereas females received muzzle contact more often than males. In addition, the low rejection rates suggest that most food items were familiar to the vervets regardless of age and sex. These findings are in line with optimal foraging theory according to which the food evaluation process should be adapted to the familiarity of food items and allows individuals to maximize their intake of energy and critical nutrients, while minimizing the time and effort in food evaluation.

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Vocal Signatures of Stress Relief: Effects of Appeasing Harness and Synthetic Pheromone on Puppy Whine Acoustics in Separation Context (Canis familiaris)

Philippe, R.; Le-Bourdiec-Shaffi, A.; Kaltsatos, V.; Reby, D.; Massenet, M.

2026-04-06 animal behavior and cognition 10.64898/2026.04.02.715714 medRxiv
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In mammals, loud, high-pitched, and harsh-sounding calls typically accompany heightened emotional arousal, particularly during distress such as separation. However, whether subtle arousal reductions can be detected through acoustic analysis within a single negative context remains unclear. We investigated whether source-related acoustic parameters of puppy whines reflect arousal modulations induced by calming interventions during maternal separation. Thirty-five eight-week-old Beagle puppies were recorded under four conditions combining synthetic appeasing pheromone and a pressure harness. Vocal behavior, activity, whine duration, and intensity, did not significantly differ across treatments, suggesting interventions did not suppress separation-related vocal responses. Nevertheless, calming products selectively altered acoustic parameters known to index arousal in dog vocalizations. Puppies receiving combined treatments produced whines with lower fundamental frequency (fo) and reduced fo variability, while pheromone exposure increased call tonality, reflected by reduced jitter and shimmer and elevated harmonics-to-noise ratios. Spectral entropy remained unchanged, possibly because the proportion of whines containing nonlinear phenomena did not vary across conditions. Reductions in fo, fo variability, and acoustic roughness are consistent with established correlates of lower arousal in mammals, suggesting source-related vocal parameters sensitively capture subtle arousal shifts even when overt vocal behavior remains stable, supporting their use as bioacoustic indicators for evaluating welfare interventions.

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Temporal consistency of judgement biases in bumblebees

Baciadonna, L.; Nityananda, V.

2026-04-09 animal behavior and cognition 10.64898/2026.04.07.716885 medRxiv
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Judgment bias tasks are increasingly used to assess affective states in animals, yet the extent to which they might reflect transient states or stable traits remains unclear. Here, we tested bumblebees (Bombus terrestris) in an active choice task across three repeated sessions to assess individual consistency in the absence of any manipulation. Bees were trained to associate each of two colours with either a high or a low reward, presented in separate chambers. During testing, they were presented with ambiguous colours. Bees were more likely to choose the high reward chamber and to choose more quickly in response to colours closer to the positive colour. The latency to choose the cues showed significant and moderate repeatability across sessions, suggesting a stable, trait-like underlying component. In contrast, the repeatability of the chamber choices was negligible, indicating that such responses might be largely state-dependent and influenced by situational factors. These findings suggest that judgment biases, particularly as assessed through an active choice task reflect states affected by external factors. Active choice tasks may help disentangle stable behavioural traits from transient affective states in invertebrates.

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Sex change in a protogynous hermaphrodite fish: life-history and social strategies in female cleaner wrasse Labroides dimidiatus

Pessina, L.; Bshary, R.

2026-04-08 animal behavior and cognition 10.64898/2026.04.06.716686 medRxiv
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Protogynous sex change, where individuals first function as females and later as males, is a key life-history strategy among polygynous reef fishes. In haremic systems, sex change is typically socially regulated, with dominants suppressing subordinates sex change through aggression. Females within a harem form a size-based hierarchy that can remain stable in most species through the threat of eviction. We studied a different situation in the cleaner wrasse Labroides dimidiatus, where larger females have incomplete control, as they spend most of their time alone at their own cleaning territory. We tracked over 400 individuals for 12 months, recording growth, behavior, social organization, and sex change. We confirmed earlier reports that both sexes direct aggression primarily at those ranked immediately below them. However, we observed 30 cases where smaller females outgrew larger ones, revealing hierarchy instability. Of 42 sex change events, 43% occurred in presence of the male, and half of these early sex changers were not the largest female, but individuals overlooked by the male. Fast growth relative to harem-mates and harem switching increased the likelihood of sex change. Local population densities also influenced growth and sex change, with individuals in high-density demes growing faster and changing sex at larger sizes. Our findings reveal flexible sex change dynamics in a system with incomplete social dominance. Such incomplete control and observations that becoming male confers both higher reproductive success and survival highlight the need to expand game-theoretical and life-history frameworks to encompass such strategic flexibility. Lay summaryDominant cleaner wrasse cannot fully control subordinates as individuals occupy distinct core areas. Tracking 400 fish for a year, we found that smaller females could outgrow initially larger ones, and early sex change despite a larger male. Fast growth and harem switching increased the chances of becoming male. Population density also shaped these strategies. Our findings reveal flexible sex change dynamics in a system where becoming male confers both higher reproductive success and survival.

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Twenty-five years of monitoring reveals that uninterrupted rodent control is the fundamental driver of breeding success in the Galapagos Petrel Pterodroma phaeopygia

Lopes, F.; Gibbs, J. P.; Carrion, J.

2026-03-30 ecology 10.64898/2026.03.29.715149 medRxiv
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The long-standing misconception that the Galapagos petrel (Pterodroma phaeopygia) and the Hawaiian petrel (Pterodroma sandwichensis) were conspecific masked the severe vulnerability of the Galapagos population. By the time its distinct status was recognized, the Galapagos petrel was already in marked decline, primarily due to invasive predators. Consequently, sustained rodent control programs have been implemented on Santa Cruz Island. An unintentional one-year failure in rodent control provided a rare quasi-experimental opportunity to quantify the demographic consequences of the invasive black rat predator. During this year, hatching success declined by [~]35% and breeding success by [~]40% relative to long-term means (66% and 62%, respectively), representing a substantial reproductive collapse. Fledging success exhibited a comparatively modest decline (from a long-term mean of 94% to 86% in 2017), suggesting stage-specific vulnerability. These results support the hypothesis that invasive black rats primarily affect early reproductive stages through egg predation and predation on small chicks, while older chicks surpass a critical size threshold that reduces susceptibility. Across the remaining managed years, reproductive metrics exhibited great stability, demonstrating the petrels resilience against other environmental or climatic stressors. Our findings provide robust empirical evidence that invasive rodent control is the dominant driver of reproductive success in this endangered seabird. The quasi-experimental failure underscored both the effectiveness and the necessity of continuous predator management, highlighting the severe and immediate consequences of even short-term lapses.

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First Evidence Of Object Play In Wild Geladas: Functional Implications For Later Utility And Re-Elaborated Object Use In Adulthood

Cordoni, G.; Porfiri, M. C.; Yitayih Hailie, Y.; Benori, A.; Bergamo, S.; Dessalegn Berhane, E.; Bogale, B. A.; Norscia, I.

2026-03-25 animal behavior and cognition 10.64898/2026.03.23.713729 medRxiv
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Object play - seemingly non-functional interactions with objects - can promote the development of foraging skills, tool use, and behavioral innovation. Among Catarrhine monkeys, it was described in macaques and baboons. Wild geladas, although closely related to baboons, have been described as lacking object play (observed only in captivity) linked to their specialized grazing ecology. Here, we provide the first evidence of both social and solitary object play in a wild gelada population (NOMUs=13) at Debre Libanos (Ethiopia) and compare it with object play in sympatric olive baboons (Nindividuals=42). Notably, immature geladas engaged in object play both socially and solitarily, but the latter case was most frequent also with novel objects introduced by researchers. Solitary object play occurred at levels comparable to those of baboons, challenging previous reports of limited object interest in geladas. This finding aligns with the occurrence of object play in phylogenetically related species and with the retention in wild geladas of arboreal behavior and fruit consumption and hand morphology enhancing fine manipulation. Hence, object play in geladas under certain environmental conditions may reflect a biologically rooted capacity and underscores the importance of ecological variability, as distinct behavioral ecotypes can emerge across different populations of the same species.

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Estimates of habitat selection reveal distinct habitat associations across life-stages in three coral-reef damselfish.

Sciamma, G.; Fakan, E. P.; Hoey, A.

2026-03-27 ecology 10.64898/2026.03.26.714170 medRxiv
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Understanding habitat association of animals and how they change through ontogeny is critical to predict the likely effects of habitat change on populations. We investigated how fine scale habitat associations of three common coral reef damselfish species changed among life-stages on reefs surrounding Lizard Island, northern Great Barrier Reef. All three species showed distinct habitat selection at settlement, however the degree to which these initial associations changed through ontogeny were species specific. Pomacentrus amboinensis associated with sandy areas throughout all life-stages; Pomacentrus chrysurus settled to areas with high cover of sand and rubble, but displayed no clear habitat preferences as juveniles or adults. Pomacentrus moluccensis settled to areas with high cover of fine branching corals before shifting to areas with relatively high cover of soft corals as adults. We also compared two different approaches to estimate habitat selection; one that quantified the benthic composition within the approximate home range of individuals versus a more widely used approach of recording a single point underneath the focal individual when they were first observed. Although results were broadly similar, the benthic composition approach revealed details that was overlooked using the single point method. Decreases in the availability of any of these preferred benthic habitats may adversely affect future populations, therefore understanding habitat associations and their transitions among life stages will be crucial in predicting future reef fish communities under ongoing coral loss and habitat change. This will require to systematically study a broader range of species, integrating relevant spatial and temporal scales.

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Reassessing display behavior from Bels et al. (2025) given the complexity of anthropogenic hybridization and intraspecific diversity in Iguana iguana

van den Burg, M. P.; Thibaudier, J.

2026-03-23 zoology 10.64898/2026.03.19.713079 medRxiv
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Understanding behavioral differences between non-native and closely related endangered species could be important to aid conservation management. In volume 169 of Zoology, Bels et al. (2025) reported on their comparison of display-action-patterns (DAP) between native Iguana delicatissima and non-native iguanas present on islands of the Guadeloupe Archipelago in the Caribbean Lesser Antilles. Here, we address conceptual and methodological concerns about their work and reanalyze their data given our proposed corrections, primarily a literature-informed adjustment of their "species" category. We additionally utilize online videos from South American mainland I. iguana populations, from where the non-native iguanas in the Guadeloupe Archipelago originate, to better understand the different DAPs between native and non-native iguanas in the Guadeloupe Archipelago. Significant differences in DAP characteristics among "species" categories (native I. delicatissima, non-native iguanas, and hybrids) show that Bels et al. (2025) oversimplified their data analyses by merging all non-native populations into one group. This result indicates the presence of behavioral variation among subpopulations within widely hybridizing iguanid populations, which has been poorly studied. Additionally, videos from mainland populations across two major mitochondrial clades of Iguana iguana show that non-native iguanas on Guadeloupe retained DAP characteristics of those populations from which they originate. We discuss these findings in light of the proposed hypotheses put forward by Bels et al. (2025), of which two can be excluded. Overall, our reanalysis shows that studies focusing on characteristics within settings of complex hybridization in diverse species should acknowledge this complexity.

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Persistent male survival advantage in a protogynous hermaphrodite fish

Pessina, L.; Bshary, R.

2026-04-06 animal behavior and cognition 10.64898/2026.04.02.716101 medRxiv
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In many polygynous species, males face stronger intrasexual competition, higher energetic demands, and lower survival than females, especially under resource limitation or environmental stress. Such sex-specific vulnerabilities are expected to intensify with climate change. Yet, in sequentially hermaphroditic systems, where individuals change sex during their lifetime, how sex and sex change shape survival remains largely unexplored. We studied sex-specific survival and growth in the haremic protogynous cleaner wrasse Labroides dimidiatus across eight reefs around Lizard Island, Great Barrier Reef. We tracked a total of 731 adult fish (individually recognizable through marking or idiosyncratic color patterns) over two years. This period included the 2024 El Nino-Southern Oscillation (ENSO), which caused a temporary 1-degree increase in water temperature, severe coral bleaching, and coral mortality at Lizard Island. Contrary to expectations from dioecious systems, terminal-phase males exhibited higher survival than initial-phase females under both normal and in particular ENSO conditions. While male mortality was not affected, female mortality more than doubled during the event, indicating greater physiological or energetic vulnerability. A partial explanation for the overall higher female mortality is their generally faster growth rate, which declined in both sexes during the ENSO event. Our findings challenge existing assumptions of male-biased mortality in polygynous species and highlight that sex and sex change fundamentally shape demographic responses to climate extremes.

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Social Distancing Responses to Fungal Disease in an Australian Wild Lizard Population

Requena-Garcia, F.; Jackson, N.; Class, B.; Mitchell, A. C.; Cramp, R. C.; Frere, C. H.

2026-04-09 animal behavior and cognition 10.64898/2026.04.06.716608 medRxiv
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Social living often confers substantial fitness benefits; however, close spatial association among individuals can also elevate opportunities for pathogen transmission, especially where the populations are dense. Despite this, the extent to which avoidance behaviours are expressed by wild reptiles facing fungal disease remains unclear. We examined Eastern Water Dragons (EWDs; Intellagama lesueurii) in Roma Street Parklands, Brisbane, Australia, where a population is affected by the emerging fungal pathogen Nannizziopsis barbatae (Nb). Using a five-year dataset (2018-2023) spanning 146 individuals, we quantified social distance, as the minimum distance to the nearest neighbour, in relation to the number of diseased conspecifics that overlapped each individuals seasonal core home area. Social distance decreased as diseased conspecifics became more numerous, indicating a strong crowding effect; however, this reduction was weaker for diseased individuals, which maintained larger distances than healthy individuals even under high disease pressure. Together, these patterns support partial social avoidance consistent with behavioural changes in infected individuals, suggesting that infection risk constrains density-driven proximity. Our findings provide new insights into how disease pressure shapes social spacing in reptiles and contribute to a broader understanding of behavioural responses to emerging infectious fungal diseases.

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From lab to ocean: bridging swimming energetics and wild movements to understand red drum (Sciaenops ocellatus) behavior in a tidal estuary

Gibbs, B.; Strother, J.; Morgan, C.; Pinton, D.; Canestrelli, A.; Liao, J. C.

2026-04-07 animal behavior and cognition 10.64898/2026.04.03.716345 medRxiv
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Understanding how fish navigate complex natural environments requires bridging fine-scale biomechanics with ecological behavior. We investigated the volitional movement and energetics of wild red drum (Sciaenops ocellatus) across laboratory, mesocosm, and field settings. Using flow-respirometry, we quantified metabolic costs and swimming kinematics under ecologically relevant flow conditions shaped by bluff bodies mimicking mangrove roots and oyster mounds. Fish swimming in turbulent wakes exhibited reduced oxygen consumption and altered tailbeat dynamics, especially at high flow speeds. In a large outdoor mesocosm, dual accelerometers revealed a rich behavioral repertoire, including maneuvering and rest, which is not easily observable in confined lab settings. Spectral analysis and clustering identified eight distinct locomotory states, highlighting the limitations of summed acceleration metrics. Field telemetry tracked wild red drum across a 54 km estuarine corridor for a three-year period through an array of 36 acoustic receivers, revealing movement patterns shaped by tidal flow and physical habitats. Hydrodynamic modeling revealed that while laboratory trials demonstrated substantial energetic savings at high flows (approaching 100 cm/s), wild fish were detected predominantly in low-velocity microhabitats (<30 cm/s) near structurally complex features. This mismatch suggests that habitat selection is an adaptive strategy driven by ecological factors such as foraging opportunities, predation refuge, and site fidelity, rather than hydrodynamic efficiency alone. Our multi-scalar approach demonstrates that while flow-structure interactions can reduce locomotor costs for fish, habitat use in the wild reflects broader ecological constraints, offering a framework for integrating biomechanics, physiology, and ecology in conservation-relevant contexts.

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Consolation behaviour in pigs: Prior exposure to group members in need of help drives targeted affiliation and facilitates social buffering

Lopez Caicoya, A.; Janicka, W.; Moscovice, L. R.

2026-04-06 animal behavior and cognition 10.64898/2026.04.02.716034 medRxiv
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We assessed whether pigs provide consolation, referring to targeted affiliation that attenuates a partners stress, under experimental conditions that manipulated exposure to stressed partners. Using a within-subject design, 74 pigs were tested in three contexts: a helping task in which group members could observe and help a trapped focal pig to return to the group, a direct-reunion, in which group members were naive to the experience of a separated focal pig until reunion, and an undisturbed control. We measured affiliative and non-affiliative interactions, anxiety behaviours and changes in salivary cortisol. Only the helping context satisfied most consolation criteria: there were selective increases in unidirectional affiliative contacts from the observer to the focal pig, non-affiliative interactions remained at baseline, and focal pigs showed fewer anxiety behaviours. In contrast, direct-reunions triggered increases in affiliative and non-affiliative interactions and higher anxiety. Cortisol increased during both direct-reunions and helping, but its level was not linked to affiliation. Results add to growing evidence for consolation behaviour in pigs and suggest best practices for reintegrating pigs into groups. Graded reintroductions that allow observers to assess the emotional state of targets may promote social buffering, whereas abrupt regrouping may trigger more generalized arousal or personal distress.

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Ruffled minds? First insights into restlessness as a potential novel indicator of impaired welfare in bulls fattened for meat production

Hintze, S.; Wildemann, T.; Krottenthaler, F.; Winckler, C.

2026-03-31 animal behavior and cognition 10.64898/2026.03.29.715061 medRxiv
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Restlessness is a symptom of chronic boredom in humans and a behavioural phenomenon anecdotally described as a concern in bulls raised for fattening purposes, but it has so far not been addressed in research. The two studies presented in this paper aimed to gain first insights into restlessness in bulls. We operationally defined restlessness by the number of transitions between behaviours in a given time period, and quantified restlessness in bulls of different weight classes (300, 400, 500 kg) on farms keeping bulls on fully-slatted floors (n=8, Study 1) as well as across three different husbandry systems (fully-slatted floor (FS, n=4), straw-based (SB, n=4) and organic pasture (OP, n=3), Study 2). All farms were visited twice, and the behaviour of different individuals was continuously recorded for 15 minutes each between 9 a.m. and 5 p.m. (Study 1) and for 8 minutes each between 6 a.m. and 10 p.m. (Study 2). The effects of weight class and husbandry system were analysed using generalised linear mixed-effects models, and we ran a sequence analysis to cluster observations by the sequence, frequency, and duration of bulls behaviours in Study 1. Bulls kept in fully-slatted floor systems in Study 1 changed their behaviour on average 48.3 times per 10 minutes, with high variability both within and across farms. Weight class did not have a statistically supported effect on the number of transitions, and the sequence analysis revealed four clusters that differed in sequence and in the number of transitions. In Study 2, OP bulls showed fewer transitions than SB and FS bulls (X22 = 23.6, p < 0.001), while SB and FS bulls did not differ. While SB pens were more structured and offered more space per animal, both SB and FS systems can be characterised by monotony, which may explain the similar level of restlessness in both systems. Alternatively, or in addition, the high feeding intensity in SB and FS systems may have caused the higher number of transitions compared to the OP system, potentially elicited by subacute ruminal acidosis and/or laminitis and the resulting pain. However, these explanations are speculative and require systematic disentanglement in future studies. This study provides initial insights into restlessness in bulls and lays the groundwork for future research to identify the causes underlying restlessness and investigate its association with bull welfare.

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Early Emergence of Auditory Quantity Discrimination in Domestic Chicks

Eccher, E.; Salva, O. R.; Chiandetti, C.; Vallortigara, G.

2026-04-09 animal behavior and cognition 10.64898/2026.04.08.717196 medRxiv
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Numerical abilities are widespread in the animal kingdom and are not exclusive to humans. Domestic chicks (Gallus gallus) have been shown to discriminate numerosities spontaneously, but prior research has focused exclusively on the visual modality. Whether chicks can discriminate numerical information in the auditory domain remains unknown, despite evidence that they can perceive other auditory features such as tone and rhythm. In this study, we investigated spontaneous numerical discrimination in the auditory modality in naive domestic chicks. In Experiment 1, newly-hatched chicks were tested for their ability to discriminate between two auditory sequences differing in numerosity (4 vs. 12 identical sounds), with and without controlling for continuous variables such as duration and total sound amount. Experiment 2 examined chicks filial imprinting responses to familiar or unfamiliar numerosities. Experiment 3 controlled for potential spontaneous preferences for a single longer sound versus a shorter one. Our results showed a preference for the 12-sound sequence only when duration and total sound amount were not matched. When these continuous variables were controlled, no spontaneous numerical preference emerged. Experiment 2 revealed an overall preference for the 12-sound sequence regardless of imprinting conditions, while Experiment 3 confirmed that chicks do not have an inherent preference for longer sounds. These findings suggest that chicks are sensitive to overall magnitude in the auditory domain but do not spontaneously discriminate numerical differences when other continuous variables are held constant. Future studies will explore how specific stimulus features, such as heterogeneity of sounds, influence these preferences.

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Convergently-evolved honeypot ants show mixed signs of niche conservatism

Nogueira, B. R.; Leon-Alvarado, O. D.; Khadempour, L.

2026-04-08 ecology 10.64898/2026.04.07.717096 medRxiv
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Honeypot ants represent an example of convergent evolution, where a group of workers specialized in storing liquid food in their crops (i.e., stomach) has independently evolved multiple times across different ant genera. While seasonal resource scarcity and arid conditions are thought to drive the evolution of repletism, the role of environmental variables in this process has not been tested. With this is mind, species ensemble models were computed to assess suitability and richness areas, and the importance of predictors. Predictor importance was compared between genera and groups occupying a similar geographical area. Niche overlap and similarity between honeypot ant species were also evaluated to determine whether they occupy similar environmental spaces. Similarity was mainly found within genera, and Leptomyrmex and Myrmecocystus showed striking niche differences. Overall, Leptomyrmex distribution was mainly influenced by atmospheric bioclimatic variables like precipitation and temperature, while Myrmecocystus had soil bioclimatic variables as the most important predictors for their current distribution. Our results indicate that honeypot ants species currently do not occupy the same environmental space, and are not experiencing the same contemporary environmental stressors. While our results suggest that contemporary environmental factors cannot explain the convergence of honeypot ants, future research will examine past climatic conditions along with investigations into the ant genomes to understand more about the causes and consequences of the convergence.