Animal Behaviour
○ Elsevier BV
Preprints posted in the last 90 days, ranked by how well they match Animal Behaviour's content profile, based on 73 papers previously published here. The average preprint has a 0.06% match score for this journal, so anything above that is already an above-average fit.
Wild, S.; Uyehara, I. K.; Todd, L. M.; Ravara, T. A.; Sih, A.; Smith, J. E.
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Human-influenced environments pose challenges but also provide wildlife with anthropogenic resources. Individuals vary widely in their ability to exploit such resources, often as a function of behavioural type. However, we lack a clear understanding of how variation in behavioural traits influences stages of resource exploitation required to use anthropogenic resources. Using fully automated foraging puzzles, we examined how boldness and sociability influenced three aspects of resource exploitation - discovery, problem-solving, and overall performance - in two wild populations of California ground squirrels (Otospermophilus beecheyi). Bolder individuals discovered the resource earlier, solved the task faster and achieved higher performance, indicating that boldness promotes efficient exploitation of anthropogenic resources across multiple stages in the process. Greater sociability and more opportunities to observe conspecifics solving the task led to faster problem-solving, consistent with evidence for observational learning. Squirrels in the recreational-use population - with regular exposure to humans and anthropogenic food - were faster to discover the resource than those in a trail-use population - where human exposure was transient and no anthropogenic food available. Problem-solving latency and performance were consistent between populations. Our findings highlight how individual variation in behavioural traits drives performance in novel ecological contexts, providing a mechanistic understanding of behavioural plasticity in human-influenced environments.
Schroth, L.; Lopes, L.; Cunha, F.
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As foraging increases exposure to predators, individuals must allocate time to vigilance in addition to food acquisition. Although those behaviors are assumed to be mutually exclusive, this is often hard to disentangle, given that multiple sensory modalities are often applied. However, when foraging, animals often have one sensory modality more impaired (e.g. vision), than others (e.g. auditory); thus, a level of compromise on vigilance capabilities is assumed while foraging. Here, we test the idea that when a food item requires manipulation, thus reducing vigilance capabilities, social foraging should promote shared costs of vigilance. We conducted video recordings to investigate whether there is a trade-off between foraging and vigilance behavior in red-legged seriemas (Cariama cristata) when foraging in pairs. We studied the social foraging behavioral patterns while seriemas were feeding on macauba palm (Acrocomia aculeata) fruit, which requires a series of throwing maneuvers to crack the hard outer shell. Our results showed that within a pair recording one individual was observed to spend more time vigilant than their partner, while the other individual spent more time throwing fruit than their partner. However, we found no evidence for synchronization or coordination of vigilance and foraging between individuals within a feeding bout. These results provide insight into the foraging ecology of red-legged seriemas and the trade-off between foraging and vigilance in social contexts.
Kang, A. S.; Mutebi, W.; Teichroeb, J. A.
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Resource handling time is an important cost to foraging animals and this is especially true for low-ranking individuals who may be displaced before they acquire rewards. Handling may also require visual attention that can lead to a trade-off between scanning the environment and focusing on food acquisition. We ran a foraging experiment on wild vervet monkeys where we simultaneously offered them three puzzle boxes in a straight-line array that increased sequentially in handling difficulty and reward value. We found that differences in competitive ability had a large impact on access to long-handling time resources and willingness to invest time in costly problem-solving when social interference was possible. Resources with lower handling time and smaller rewards were accessed by individuals of all dominance ranks but only dominant monkeys that did not fear displacement attempted the high handling time puzzle box. Handling time improved with experience at each puzzle box and contrary to predictions, when vigilance rates were higher, monkeys were also faster at solving puzzle boxes. Thus, there is not necessarily a trade-off between attention to foraging tasks that require handling and vigilance, if a high scanning frequency to both can be balanced with limited scanning duration. These results have important implications for understanding the decision-making of foraging animals that live in competitive groups and the diets of individuals, which may vary with dominance when important resources require long handling times.
Kern, V.; Capitain, S.; Wirobski, G.; Arias-Sarah, P.; Newson, M.; Van de Waal, E.; Range, F.
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Chorus howls play a central role in wolves' (Canis lupus) social communication, shaping both intra- and inter-pack interactions. While synchrony has been shown to influence perceived threat from outgroups in birds and humans, whether the synchrony of an outside pack's chorus howl plays a role in wolf pack behaviour remains unclear. This study investigated behavioural responses of 19 zoo-housed wolf packs to playbacks of synchronous and asynchronous chorus howls from unfamiliar packs, in comparison to a dove control call. We hypothesized that packs would show stronger intra-pack cohesion and greater spatial withdrawal in response to more synchronous, and thus cohesive - and potentially more formidable - sounding vocalisations. Alternatively, asynchronous howls might elicit stronger responses due to their ambiguity and the "Beau Geste" effect (where asynchronous signals make it harder to infer the number of callers). Synchronous howls resulted in more distance from the sound source and less activity compared with asynchronous howls. This could be interpreted as a more cautious response towards a perceived threat. However, since there was no effect on pack-directed behaviour and no difference between the synchronous and control sound, lower interest or motivation to engage with the stimulus cannot be excluded. In contrast, wolves spent more time near the sound-source after hearing asynchronous howls, approached it more, and oriented towards it for longer compared to synchronous playbacks, a pattern consistent with threat-investigation. In how far these reactions result from a more difficult localisation of synchronous howls or more ambiguity in pack size in the asynchronous playbacks, as well as how this translates to wild wolf behaviour, remains to be investigated.
Wierucka, K.; Winiger, S.; Sehner, S.; Burkart, J. M.
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Foraging and feeding are often associated with vocalisations across animal species. Food calls may function to claim ownership of resources or recruit others to feeding sites, yet their potential role in facilitating food sharing remains poorly understood. This study investigates the relationship between food calls and food-sharing behaviour in common marmosets (Callithrix jacchus), focusing on adult-infant interactions, where food transfers are most frequent. We analysed over 1000 food interactions across six groups, categorising events as non-sharing (without begging or despite begging) or sharing (proactive, resisted, or facilitated). We examined the spectro-temporal structure of food calls produced immediately before each interaction. Food transfers were more likely to occur when preceded by a food call, suggesting a functional link between food calls and sharing. Random forest models reliably classified food calls according to interaction type, while generalized linear mixed models identified acoustic variation associated with sharing outcomes. Our results suggest that food calls encode information to either encourage or deter conspecific (infant) approach, influencing food transfer outcomes. These findings highlight the role of food calls in modulating social interactions around food in marmosets, advancing our understanding of vocal communication and its integration with cooperative behaviours in primates.
Kranenburg, K.; Cunha, F.
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Decision-making is key to survival, with choices and behaviour typically shaped by evolutionary pressures to enhance fitness and minimize loss. Inequity aversion, the tendency to respond negatively to unequal reward distributions, is therefore unexpected, as acts of fairness may be costly to the individual in the short term. In social, cooperative species, however, fairness may enhance long-term benefits through stable social interactions. Inequity aversion is believed to promote cooperative social structures and has only been demonstrated in certain social species. Yet, solitary species have not been tested, and whether this behaviour depends on social cooperative structures is unknown. Examining solitary species could clarify whether inequity aversion reflects an adaptation to cooperation or a general cognitive capacity linked to social comparison and reward evaluation. We studied inequity aversion in polar bears (Ursus maritimus), a largely solitary species, using three complementary, non-invasive cognition tests on seven bears from two zoos in the Netherlands. (1) An impunity experiment assessing effort-based inequity, in which bears performed a standardized action to obtain food rewards. (2) A choice-based experiment testing active selection between equal and unequal reward distributions. (3) A no-task control experiment assessing responses to unequal reward distribution without effort. Under effort-based inequity, bears reduced task performance and increased task latency when a partner received a superior reward. Unequal reward distributions did not affect reward acceptance independent of effort. In the choice-based paradigm, bears preferentially selected equal reward distributions with a partner present. Although generalizability to wild populations is limited, these findings demonstrate behavioural aversion of social inequity in a non-cooperative species. Inequality aversion may therefore not be restricted to social, cooperative animals but instead reflect a broadly distributed cognitive mechanism that emerges under relevant social conditions. These findings challenge current theories and advance our understanding of the cognitive foundations of fairness-related behaviour in animals.
Ramesh, A.; Stamhuis, E.; Nicolaus, M.
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Schooling is a widespread behaviour among pelagic fish that reduces locomotion costs of migration and predation risk. It is characterised by coordinated movements, speed and orientation of group members. Although schooling can vary both between populations and among individuals of the same population, these levels of variation are seldom considered together. Here, we investigated whether schooling tendencies in three-spined sticklebacks (Gasterosteus aculeatus) vary between populations and among individuals within-populations depending on their phenotype. We first compared the schooling behaviour of anadromous (migrants) and recently landlocked (residents) populations and tested whether individual sociability explained within-population variation in schooling. We then studied whether schooling behaviour is modulated when migrants and residents are in mixed groups. Migrant groups displayed better schooling performance than residents with higher alignment. Within migrant groups, less social individuals displayed more leadership, were better aligned, swam closer to others and fatigued less than more social fish. These patterns were absent in residents. When the two populations were mixed, overall schooling performance declined, particularly in migrants, with schools exhibiting reduced compaction and alignment, resembling resident groups. Thus, individuals did not modulate their schooling behaviour to the group social composition and phenotype-dependent schooling patterns were disrupted in migrants when mixed. These findings suggest that migration-related behaviours can disappear quickly post-isolation. They also highlight the importance of individual sociability in self-organisation and shaping collective behaviour, especially in populations that retain migratory behaviour. Considering behavioural variation across multiple hierarchical levels is thus key to understanding complex social systems.
Pal, T. S.; Biswas, S.; Bhadra, A.
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Animals often display active decision-making while navigating noisy habitats, for varied purposes like foraging, finding shelter, evading predators or finding suitable mates. While some responses are hardwired, following fixed action patterns, others are more flexible, and display context-dependent plasticity. Animals might weigh behavioural consistency against adaptive plasticity when facing recurrent ecological difficulties, but the nuanced mechanisms orchestrating this balance is not well understood. We investigated this question by repeatedly exposing 47 free-ranging dogs to chicken contaminated with lemon solution, an aversive but edible and familiar food source, across four consecutive trials. By integrating behavioural frequencies, latency measures, feeding efficiency, interaction-time and location effects, repeatability analyses, and behavioural sequence structure, we examined how repeated experience influenced foraging behaviour. Contrary to expectations of broad behavioural reorganisation, most behaviours remained stable. Initial approach latency was strongly repeatable within individuals with no detectable influence of sex or trial number across the population. This suggests that how an animal first assesses risk is primarily shaped by stable personality traits rather than momentary external factors. Eating behaviour and bowl nudging also changed selectively across exposures, with modest sex differences in several behaviours. Behavioural sequences became increasingly similar over time, while several behaviours retained consistent individual differences, indicating persistent behavioural tendencies. Our results collectively demonstrated that repeated aversive exposure selectively modified a few critical decision points rather than the entire behavioural repertoire. This implies that animals can adapt by making small adjustments to specific behaviours while maintaining the stability of their overall behavioural architectures. Animals seem to assess risk separately from how well they use resources. That separation may help explain how stable personalities can coexist with the fast, flexible decisions animals need in unpredictable environments shaped by humans.
Gleason, M.; Krieg, C.; Ododm, K.
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Female-female competition is increasingly recognized as a key driver of female ornamentation, including birdsong, which often functions in intrasexual competition. However, the specific resources females use elaborate traits to compete for remain unclear. In addition, few studies have simultaneously investigated the use of multiple competitive traits in females, despite growing independent interest in these traits (e.g., female song and aggression). We investigated the competitive contexts of female song, aggression and calling behavior in northern house wrens (Troglodytes aedon) to determine which resources females compete for across the breeding season. We simulated conspecific territorial intrusions using female song at three breeding stages representing different contexts: arrival (mate and territory acquisition), nest building (nest site and breeding status defense), and egg laying (brood defense). We tested whether female song and physical aggression varied as reproductive resources shifted across the breeding cycle. Females were significantly more aggressive during nest building, showing 5.8 times greater odds of a higher-intensity aggressive response during nest building compared to arrival. Female song output was similar across early stages but declined during egg laying, though this was not statistically significant after correction for multiple comparisons and individuals varied substantially in overall singing propensity. Non-song vocalizations varied by call type and breeding stage. Calls associated with aggression occurred most frequently during nest building, consistent with peak physical aggression responses. Together, these results identify nest building as the stage of highest female aggression, consistent with heightened competition over nest cavities and associated breeding status in this cavity-nesting species. In contrast, female song occurred across all stages and appears to function in multiple competitive contexts. This study provides evidence for context and mode-specific female signaling in a temperate songbird and highlights that females strategically use aggression, calls, and song to mediate social conflict across breeding contexts.
Nederlof, A. M. N.; Kappelhof, J.; Schel, A. M.
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The social complexity hypothesis for communication posits that species with elaborate social systems require more sophisticated vocal communication to navigate social life. Geladas (Theropithecus gelada), who live in complex multilevel societies and form diverse social bonds, are ideal for testing this hypothesis. Males produce species-specific, or derived, calls that reflect social status and function in facilitating male-female bonding. However, although derived call use also occurs in male-male social interactions, their function in male-male communication remains unexamined. In this pilot study we investigate the use of derived calls within a captive all-male bachelor group and test two hypotheses: (1) derived calls signal bachelor dominance status, and (2) derived calls function to maintain male-male social bonds. Despite a limited sample size, our results show that bachelor leaders produce higher proportions of derived calls than bachelor followers, mirroring patterns found in harem groups. Furthermore, bachelor followers were most likely to use derived calls in affiliative and resting contexts, suggesting a role in social bonding. In contrast, bachelor leaders used them more broadly. They additionally produced derived calls during agonism and travel, thereby possibly reflecting their more elaborate leadership duties. These findings provide the first preliminary evidence that derived calls serve functions beyond male-female communication and may be integral to both status signalling and affiliative interactions among bachelor males. Our results on the vocal dynamics in male geladas shed further light on the co-evolution of social and vocal complexity and offer broader implications for the origins of human language.
Sosa-Negron, P. A.; Sosa-Lopez, J. R.; Barrantes, G.; Sandoval, L.
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Individual variation in singing behavior is influenced by cultural evolution, environmental constraints, and population dynamics. In closed-ended songbird species, aging may be associated to temporal song variations in individual birds due to vocal apparatus deterioration. However, song variations may also arise as a result of extrinsic factors that induce behavioral changes. In this study, we aimed to examine song-type consistency over 13 years in four populations of the White-eared Ground-sparrow (Melozone leucotis, Aves: Passerellidae) along an urban-rural gradient. We also compared within and between-individual variation to determine potential population-level responses. We used long-term data from singing males to quantify five fine structural characteristics (minimum frequency and maximum frequencies, bandwidth, peak frequency, and song duration) for two most common song types from each population. Song consistency differed between fine-structure characteristics, song types, and populations. Contrary to our expectations, we found that the Highly urbanized population had greater between-individual variance, associated with anthropogenic disturbances such as habitat structure and noise pollution, suggesting non-uniform individual responses. The Medium, Low urbanized, and Rural populations, on the other hand, had higher levels of within-individual variance, associated to individuals' age. Our study brings insight into how both intrinsic and extrinsic factors can influence song consistency and highlights how cultural evolution within a species can diverge across populations experiencing distinct environmental contexts.
Buda, K.; Buda, J.; Budka, M.
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The vast majority of birds are diurnal and concentrate their vocal activity during daylight hours. However, some diurnal birds can also be vocally active at night, although the functions of this phenomenon remain poorly understood. We conducted playback experiments in the Warta Landscape Park (central Poland) to determine whether nocturnal singing by diurnal birds serves breeding-related functions by analysing responses to playback of songs from unfamiliar conspecific males. The sedge warbler (Acrocephalus schoenobaenus) was selected as the focal species because it exhibits relatively high levels of nocturnal song activity, while nine additional diurnal species detected near focal sedge warbler territories were included to explore whether responsiveness to nocturnal conspecific song extended across a broader taxonomic range. Playback experiments were conducted during the early and late stages of the breeding season and during the early and late parts of the nautical night. Out of 10 species tested, three responded vocally: sedge warbler, Savi s warbler (Locustella luscinioides), and common snipe (Gallinago gallinago). Sedge warblers did not modify song rate and song duration but increased flight activity after nocturnal playback. Savi s warblers and common snipes produced more vocalisations after playback than before in May, a pattern consistent with territorial defence function. General nocturnal vocal activity was higher at the beginning of the season, suggesting that birds motivation to establish territories and form pairs can extend into the night, providing additional benefits. Moreover, the probability of singing by the sedge warbler was higher in the latter part of the night. Our study demonstrates that nocturnal stimulation of foreign male playback of diurnal birds can elicit vocal responses from conspecifics, suggesting that nocturnal singing can occur in the absence of obvious artificial light pollution, but in the case of some species and environmental conditions, it may contribute to nocturnal social communication, especially in the early breeding season.
Takahashi, K.
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When food resources provide reward while simultaneously imposing risk, animals can regulate their behaviour to continue exploiting them while reducing associated costs. Angling presents such a feeding situation, in which obtaining bait can result in hooking and capture. Although fish become less vulnerable to angling following capture experience, the behavioural changes underlying this reduced vulnerability remain poorly understood. Here, we used fine-scale video observations to examine feeding behaviour of red sea bream (Pagrus major) toward angling gear before and after capture experience. Naive fish rapidly swallowed the bait and were subsequently captured, whereas capture-experienced fish continued to approach and feed on the gear but shifted from swallowing to biting. This feeding-mode shift may allow fish to maintain exploitation of the bait while reducing capture risk. Our observations provide a behavioural explanation for reduced angling vulnerability and suggest that direct experience with capture risk can alter how fish exploit a rewarding food resource.
Rossi, N.; Nicholls, E.
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Environmental predictability influences the value of information acquired through experience, yet relatively little is known about how instability in resource characteristics influences behavioural organisation during foraging. We tested whether repeated changes in floral orientation, a manipulation of environmental predictability, affect pollen foraging in bumblebees (Bombus terrestris) by exposing naive workers to either stable floral conditions (single flower orientation) or repeated inter-trial changes in flower orientation (three alternating flower orientations), under constant resource availability. We quantified pollen collection, foraging efficiency, revisitation behaviour, floral coverage and sonication behaviour across three successive foraging trials of either constant or variable flower orientation, before assessing performance in a common post-treatment preference test in which bees were offered all three flower orientations and higher pollen rewards. Environmental instability altered the organisation of foraging behaviour. Bees exposed to unstable floral conditions progressively reduced flower revisitation behaviour and were less likely to perform sonication, although floral coverage, defined as the number of unique flowers visited, remained unchanged. Contrary to our predictions, instability had only weak immediate effects on pollen acquisition and foraging efficiency compared to bees tested under stable conditions. However, previous exposure to instability generated carry-over effects in the common post-treatment preference test. Bees previously exposed to unstable conditions were significantly less likely to return with pollen and consequently collected less pollen overall than bees previously exposed to stable conditions. Our results demonstrate that environmental instability can influence pollen foraging in ways that are not captured by immediate measures of performance. Although behavioural adjustments appeared to buffer short-term consequences during repeated foraging trials, carry-over effects were evident when bees were later tested in a common high-reward, multi-orientation floral array. These findings highlight the importance of considering both behavioural flexibility and carry-over effects when evaluating how organisms respond to changing environments.
Pery, M.; Rivain, M.; Le Floch, G.; Gelinaud, G.; Deffes, O.; Petry, A.; Baguette, M.; Bels, V.
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Shorebirds provide an excellent model for investigating the relationship between bill morphology and food acquisition. Food acquisition comprises three successive behavioural stages: foraging (locomotion and prey capture), feeding (food handling and transport), and swallowing. During food transport, these birds use two non-lingual mechanisms, surface-tension transport (ST) and ballistic transport (BT), whose characteristics depends on the kinematics of head and beak movements and the physical properties of the food. We investigated the behavioural flexibility of these transport mechanisms in captive and free-ranging individuals of two species with contrasting beak morphologies: the Pied avocet (Recurvirostra avosetta) and the Black-winged stilt (Himantopus himantopus). Although these species have beaks of a similar size, avocets are distinguished by their upward-curved beaks, whereas stilts have a rather straight beak. We examined the effects of food water content and the presence or absence of water in the beak on food transport by quantifying maximum gape, maximum head displacement, and maximum head velocity. Transport kinematics were jointly influenced by food properties and water availability in the beak. Moist food improved transport performance in both species, whereas dry food required compensatory increases in gape amplitude and head movements, demonstrating that neither ST nor BT constitutes a fixed behavioural sequence. Species also differed consistently in their transport strategies: Black-winged stilts relied on slower, larger-amplitude head movements, whereas Pied Avocets exhibited faster, more precise movements, particularly when water was present. These findings demonstrate that ST and BT share common biomechanical foundations while being governed by rapid kinematic adjustments to changing environmental conditions that probably correspond to flexible motor control. This behavioural flexibility in food transport is therefore likely to enhance feeding performance and ecological resilience in the heterogeneous habitats occupied by shorebirds, suggesting that context-dependent modulation of transport behaviour represents an important adaptive feature of these shorebirds.
Wakita, M.
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Budgerigars (Melopsittacus undulatus) are vocal-learning birds with well-developed auditory abilities, but how they behaviorally evaluate melodic and rhythmic structure in sound sequences remains unclear. We examined whether budgerigars show preferences for these acoustic features and whether such preferences differ between the sexes. Three male and three female budgerigars were presented with four 8-s sound sequences in a preference apparatus: Simple (no pitch or temporal variation), Melody (pitch variation only), Rhythm (temporal variation only), and Complex (both pitch and temporal variation). Preference was quantified as the time spent in the area associated with each stimulus. No statistically significant differences among the four stimuli were detected within individuals. However, effect-size estimates indicated that two females spent more time with sequences containing rhythmic structure, whereas males showed no consistent preference related to either melodic or rhythmic components. Multidimensional scaling further suggested greater separation among stimulus conditions in females than in males. Consistent with this pattern, condition differentiation indices were higher in all three females than in all three males, although the sex difference was not statistically significant. These results suggest a possible sex-related difference in how budgerigars behaviorally weight temporal structure, with females showing greater differentiation among auditory sequence types under the present testing conditions.
Ham, K.; Park, S.; Park, G.; Kim, C.
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Japanese quail (Coturnix japonica) rely on an extensive vocal repertoire to coordinate social behaviour and respond to predation risk, yet how individual call types are modulated by predator identity remains poorly characterized. In this pilot case-series, two sexually mature Japanese quail (each contributing more than 2,000 classified vocalizations across repeated predator-exposure trials) were exposed to simulated aerial (hawk) and terrestrial (cat) predator stimuli across four social contexts, before, during, and after stimulus presentation. Vocalizations were classified, via blind dual-observer review, into 18 spectrographically distinct call types (an exploratory repertoire estimate, not independently statistically validated), of which 10 were acoustically characterized. Chi-square analyses of the full call-type composition revealed highly significant differences between hawk and cat exposure in both individuals (both p < 0.0001); call types 5 and 10 were significantly cat-biased and call type 2 was significantly hawk-biased in both individuals. An exploratory correlation suggested that call types with a higher maximum frequency tended to be relatively hawk-biased (Spearman rho = -0.67, p = 0.033, uncorrected for multiple comparisons). Independently, call-type composition shifted significantly between the pre- and post-exposure phases in all four individual-by-predator combinations (all p < 0.0001), driven substantially by a consistent post-exposure increase in call type 9 across both individuals and both predator classes. Additional exploratory analyses of social-context (mirror and concealed-conspecific) effects on call-type composition are presented in the supporting information. Given the small sample size (n = 2), these findings are presented as case-based, hypothesis-generating observations intended to justify and inform a fully powered follow-up study, rather than as population-level conclusions.
Collins, L.; Joly, M.; Micheletta, J.; Kaminski, J.
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Primates maintain cooperative relationships largely through grooming reciprocity, yet studies disagree on the timescales over which grooming is returned. Part of this disagreement stems from statistical issues: inconsistent definitions of a reciprocation window, combined with the exclusion of unreciprocated grooming, leave the debate unresolved. We still do not know if primates exchange grooming within the short windows predicted by biological market theory or over much longer timescales. Whilst survival analysis can identify reciprocation windows objectively by retaining unreciprocated grooming as censored data, previous studies have applied it inconsistently. This inconsistency leaves the true time frames over which primates reciprocate grooming somewhat blurred. Here, we use a statistical approach that addresses these problems to examine grooming reciprocity in crested macaques (Macaca nigra), a socially tolerant macaque species. We applied survival analysis to identify each group's short-term reciprocation window without imposing arbitrary cut offs, and Bayesian survival models to test whether social bond strength and eigenvector centrality predicted reciprocation latency. Short-term reciprocation occurred rarely (29% of events in one group and 5% in the other); most reciprocation occurred over longer timescales than previous research commonly assumes. Stronger bonds predicted faster reciprocation; this finding suggests that crested macaques express social investment in valued partners through how promptly they return grooming, meaning that the timing of exchange carries information about relationship value. Eigenvector centrality showed no credible effect, though our small sample size and dense groups prevent us from interpreting this outcome more robustly. Substantial variation between dyads remained unexplained, pointing to partnerspecific properties we have yet to identify. These findings caution against assuming that reciprocity operates over short windows. They show that social predictors, such as bond strength, remain essential to understanding when primates return grooming. This work provides a baseline for testing whether grooming is exchanged for other social commodities, and for comparing reciprocation timescales across macaque species that differ in social tolerance.
Cipriano, A. P.; Menezes, C.; Munro, M.; Bell, E.; Gruter, C.
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Stingless bees are key pollinators of native and cultivated plants, and their management mostly for honey and hive commercialisation has become an increasingly popular practice in Brazil. Hives are commonly kept close together and visually similar in meliponaries, a practice that favours drifting, i.e., the return of foragers to a foreign nest. Distance between hives and layout have been identified as drivers of drifting in the Western honeybee, but evidence for stingless bees, the largest group of social bees, remains scarce. Additionally, stingless beekeepers frequently associate drifting with weakened colonies, uneven honey production, worker fighting, and colony population imbalances. We investigated the effects of hive layout on foraging traffic and drifting in the stingless bee Melipona quadrifasciata. We compared forager traffic across six layouts varying in distance, colour and entrance orientation. Then, using RFID tags, we tracked drifting across three layouts with the same inter-hive distance but different designs: visually similar hives, hives with opposite entrance orientation, and hives painted with distinct colours. Forager traffic was lowest in the visually similar layout during the first two weeks of monitoring, which is consistent with greater disorientation in the absence of clear visual cues. Hive position was a key driver of drifting behaviour across all layouts, with bees from edge hives drifting considerably less than those from inner hives. Drifting decreased considerably in hives with different colours (37.6%) and hives with entrances in opposite directions (48.1%), compared to similarly looking hives with entrances in the same direction (59.5%). Therefore, our findings highlight practical low-effort strategies for stingless beekeepers to reduce forager loss, pathogen spread, and productivity losses.
Blum Moyse, L.; El Hady, A.
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The mechanisms by which organisms extract relevant information from complex sensory signals and use it for decision-making constitute a fundamental issue in biological and cognitive sciences. In social animal societies, individual decision-making is profoundly shaped by information provided by conspecifics. Collective patch-foraging experiments in the laboratory provide a controlled setting in which social information use can be quantified. Here, we consider a go/no-go task in which groups choose between two patches differing in food reward probability. We use agent-based simulations, underpinned by an augmented collective drift-diffusion model, to investigate alternative mechanisms for representing and integrating social information. We consider two representations, continuous (counting representation) and discrete (pulsatile representation), and two integration mechanisms, biasing the decision threshold (threshold modulation) and modifying the accumulated belief (belief modulation), yielding four distinct social models, in addition to a non-interacting model. We first characterize the collective dynamics generated by these models across cognitive parameters and experimental conditions. The temporal dynamics of group accuracy provide informative signatures of the underlying mechanisms. We then assess model selection and parameter identifiability using Bayesian inference and Wasserstein distance minimization, applied to group-accuracy and departure-time distributions. Bayesian inference using distributions of group accuracy provides the most reliable identification across the conditions considered. Importantly, model selection and parameter identifiability are associated with different aspects of collective behavior: model selection is closely linked to the presence of oscillations in the temporal dynamics, whereas parameter identifiability is more closely related to the global accuracy value. Thus, the information available for distinguishing the underlying cognitive mechanisms is not necessarily the same as that required to recover their parameters. Our results further show that identification depends not only on model structure but also on the experimental conditions. Overall, this study provides practical guidelines for identifying socio-cognitive mechanisms in collective foraging experiments.