Biology subjects

Robira, B.

Publications and source records attributed to Robira, B..

10 recordsLinked to original sources

bioRxiv2026

Spatial segregation and multi-scale space-use adjustments to socio-ecological variables in western gorillas

Background: Identifying the mechanisms that shape space-use dynamics and the scale at which they operate can provide insights into the socio-ecology of numerous animal species. This is crucial for addressing both applied (e.g., conservation) and theoretical questions (e.g., the coexistence or segregation of individuals). Yet, longitudinal views of the space-use dynamics are generally rare. Taking advantage of a long-term movement dataset (up to 8 years) on five habituated groups of wild western gorillas (Gorilla gorilla) in Central Africa, we investigated the dynamics of their space use in relation to the socio-ecological variables from everyday movement to home range shifts. Methods: We looked at which temporal scale their ranging movements are stationary to highlight the dynamics of home range settling and shifts. We also studied how daily space use is shaped by (i) foraging and intra-group constraints (i.e., diet, group size, presence of offspring), and by (ii) inter-group competition (direct or indirect), quantifying static and dynamic interactions in neighbouring group-dyads. Results: Gorilla groups shifted the centre of their home range 0.17 times per year by a distance larger than the mean home range radius. Movements within the home range were highly dependent on the group composition and the ecological features (with larger daily-travelled distances in the high-fruit season compared to the low-fruit season). The presence of dependent infants affected the daily-travel distance: the larger their number, the smaller the daily-travel distance. Furthermore, the frequently visited sites of the home range were also used the longest, but their locations differed seasonally, suggesting space use flexibility. Although there was little overlap between the home ranges of neighbouring groups, these groups did not seem to avoid each other more than expected at random. They could even venture into, and slept in, the central part of the home range of a neighbouring group. Conclusion: Our study suggests that spatial segregation should be the simple consequence of avoidance of depleted areas rather than of territorial behaviour. It shows how socio-ecological constraints may shape the space-use patterns at different scales in a non-territorial species, and questions the role of cognition in space-use dynamics.

ecology↗

bioRxiv2026

The ecology of remembering and forgetting: quantity-quality trade-offs in the spatiotemporal memory of a forager

One way that animals can cope with the challenge of locating ephemeral food in time and space is by tracking elapsed time and planning revisits to these resources. These abilities likely evolved under constraints of memory capacity. We expect that during evolution a trade-off emerged between a large memory size (quantity) and high accuracy (quality) of information. We used computer simulations of a forager moving through space and time to investigate how timing accuracy, memory size, and forgetting affect foraging efficiency across environmental conditions, and how foragers should trade off the quantity against quality of memorised information. Memory in general paid off, as it improved foraging efficiency. However, surprisingly, the largest accuracy and size were not always most beneficial. In resource-poor, heterogeneous, and highly dynamic environments, extensive memory was even detrimental, as individuals likely became trapped in overexploited familiar areas. This suggests that under certain environmental conditions, a hidden, non-energetic cost of memory can arise. Furthermore, environmental structure shaped a quantity-quality trade-off such that a minimal memory size and higher timing accuracy were favoured in resource-poor, temporally stable and homogenous environments. Finally, forgetting was beneficial when memory was constrained, and environments were poor, heterogenous and dynamic. Forgetting limited the benefits of increased memory size, highlighting that memory costs can emerge from how it shapes movement patterns and foraging decisions. Overall, our results highlight that larger and more accurate memory is not necessarily better and that forgetting can be adaptive. This study takes a first step toward the theoretical consideration of memory trade-offs in order to research how they shape, and are shaped, by foraging pressures. Author summaryHow can we explain foraging memory abilities differences in animals? In this study, we make an attempt to elucidate the current patterns of temporal memory using a computational model that was inspired by realistic environmental and cognitive mechanisms. Building on our previous theoretical and empirical investigations of the causes and consequences of spatiotemporal memory, we provide new insights into the ecological drivers of temporal memory, how they shape an accuracy-size trade off, and its consequences for movement behaviour. We show that a larger memory is favoured, at the cost of accuracy, in resource-rich and dynamic environments. Our results highlight that while memory is generally beneficial, a larger and more accurate memory is not necessarily better. Moreover, our model suggests that such constraints of memory stem from a hidden cost of how memory restricts movement and instigates local overexploitation. Our findings contribute to a broader understanding of how cognition evolves in response to ecological conditions.

animal behavior and cognition↗

bioRxiv2025

Living with urban fear: vervet monkey response to an evolutionarily new predator

Humans have facilitated contacts between prey and predator species that have originally not co-evolved, reshuffling the prey-predator arms race. How do prey cope with an evolutionarily new predation risk? We tracked three vervet monkey troops in a South-African semi-urban habitat for 14 months to study their response to domestic dogs. We show that monkeys responded to dogs with a two-pronged behaviour: they emitted alarm calls, and became more vigilant and displayed aggressive behaviours towards the dogs. While their movement highlighted risk-prone behaviour, they appeared to have mapped and planned for risk, as they reacted more strongly when risk was unexpected. The response intensity was further modulated by risk labels typically encountered in their natural environment, but not by labels uniquely associated with dogs. This highlights that vervet monkeys responded with ingrained behaviour to this evolutionarily new threat, anticipating risk based on long-term spatial memory, but failed to integrate evolutionarily new information. TeaserVervet monkeys fear domestic dogs but fail to adjust their antipredator response by discriminating evolutionarily new risk labels.

animal behavior and cognition↗

bioRxiv2025

Behavioural flexibility and its drivers in semi-urban vervet monkeys

Phylogenetic comparisons suggest that behavioural flexibility facilitates success in urban environments. It remains less clear whether urbanization fosters cognitive skills that require flexibility, or whether successful individuals in urban environments simply apply pre-evolved skills to solve new problems. To investigate whether variation in anthropogenic experience drives behavioural flexibility required to solve a new technical problem, we presented 42 semi-urban vervet monkeys (Chlorocebus pygerythrus) with a three-phase foraging experiment. For this, we measured each monkeys tendency to "raid" human structures in their search for food to assess whether their anthropogenic experience explained individual variation in flexibility and problem-solving skills. We then used a probabilistic model to describe the series of monkeys actions when attempting to solve the foraging experiment. This allowed us to quantify three traits encompassing individuals behavioural flexibility: switch tendency between solutions, innovativeness, and learning sensitivity. We found that individuals switch tendency and innovativeness were not explained by anthropogenic experience and that the three traits were unrelated to each other. Moreover, neither switch tendency, nor innovativeness predicted the monkeys human food consumption in this habitat. Thus, our study suggests that behavioural flexibility is not driven by anthropogenic foraging experience. Contrasting with the hypothesis that urbanization selects for behavioural flexibility, our findings instead imply that vervet monkeys already had the sufficient behavioural flexibility and cognitive capacities to successfully exploit the urban habitat.

animal behavior and cognition↗

bioRxiv2024

Movement responses to lethal risk: an integrative analysis of proactive and reactive antipredator behaviours in a large herbivore

Prey species can display antipredation movement behaviours to reduce predation risk including proactive responses to chronic or predictable risk, and reactive responses to acute or unpredictable risk. Thus, at any given time, prey movement choice may reflect the trade-off between proaction and reaction. In previous studies, proaction and reaction have generally been considered separately, which neglects their simultaneous influence on animal decisions. In this study, we analysed how proaction and reaction interact to shape the movements of GPS-collared red deer (Cervus elaphus), in response to human hunting of conspecifics. Our results show that red deer proactively selected canopy cover where and when risk was predictably high. However, when they were unable to avoid risk, canopy cover was no longer selected, but only modulated a reactive response along a freeze-to-escape continuum. This reaction was even more evident when the environment was unfamiliar, underlining the importance of memory in such reaction patterns. Therefore, to our knowledge, for the first time, we describe how proaction and reaction fuse in an antipredation sequence of interconnected movement decisions in a large herbivore, and we lay the foundations for further investigations into the evolutionary origins of similarities and differences between proactive and reactive behaviours.

ecology↗

bioRxiv2023

The role of cognition and movement of seed-dispersing animals in shaping plant distributions

In the scenarios concerning the emergence and selection of spatiotemporal cognitive abilities in vagile plant-eating animals, there is always an implicit assumption: the distribution of plants does not change and ultimately shapes the cognitive abilities of the animals, hence their movement. Yet, if plant distribution patterns are likely to remain unchanged over short time periods, they may change over long time periods as a result of animal exploitation. In particular, animal movement can shape the environment by dispersing plant seeds. Using an agent-based model simulating the foraging behaviour of a seed disperser endowed with spatiotemporal knowledge of resource distribution, I investigated whether resource spatiotemporal patterns could be influenced by the level of cognition involved in foraging. This level of cognition represented how well resource location and phenology were predicted by the agent. I showed that seed dispersers could shape the long-term distribution of resources by materialising the routes repeatedly used by the agent with the newly recruited plants. This stemmed from the conjunction of two forces: competition for space between plants and a seed-dispersing agent moving from plant to plant based on spatiotemporal memory. In turn, resource landscape modifications affected the benefits of spatiotemporal memory. This could create eco-evolutionary feedback loops between animal spatiotemporal cognition and the distribution patterns of plant resources. Altogether, the results emphasise that foraging cognition is a cause and a consequence of resource heterogeneity.

ecology↗

bioRxiv2023

Unravelling vulture avoidance tactic of wind turbines combining empirical and simulation data

The increase of wind turbine installations to limit climate change may affect bird populations because of collisions with rotor blades. Birds may respond to wind turbine presence along a gradient of behavioural changes: avoiding the wind farm (macro-scale) or only the wind turbines either by anticipating wind turbine locations (meso-scale) or engaging into last-minute flee attempts after late perception (micro-scale). We investigated the flight response at these three spatial scales of 25 adult griffon vultures (Gyps fulvus) equipped with GPS tags over three years when flying in an area including ten wind farms in the Causses, France. At macro-scale, the population foraging range and habitat use revealed that vultures did not avoid wind farms. To investigate avoidance at meso- and micro-scales we focused on the four mostly visited wind farms. We compared vulture flights to null movement models, based on a method allowing us to keep the correlation between flights and topography while creating movement independent of wind turbine locations. At most sites, vultures did not show avoidance behaviour. Yet, simulations from our agent-based model highlighted that the avoidance pattern detected at one wind farm matched with an anticipated avoidance of turbines, probably linked to the presence of a ridge nearby. Overall, our results suggest wind farm-specific responses by soaring birds as a function of the landscape topography. Thus, stakeholders should carefully consider the wind farm location for siting and designing preventive measures (e.g. improve detection of species not able to avoid turbines in switching off on-demand technologies) to reduce collision risk of soaring birds.

animal behavior and cognition↗

bioRxiv2023

The use of social information in vulture flight decisions

Animals rely on a balance of personal and social information to decide when and where to move next in order to access a desired resource, such as food. The benefits from cueing on conspecifics to reduce uncertainty about resources availability can be rapidly overcome by the risks of within-group competition, often exacerbated toward low-ranked individuals. Being obligate soarers, relying on thermal updrafts to search for carcasses around which competition can be fierce, vultures represent ideal models to investigate the balance between personal and social information during foraging movements. Linking dominance hierarchy, social affinities and meteorological conditions to movement decisions of eight captive vultures, Gyps spp., released for free flights in natural-like soaring conditions, we found that they relied on social information (i.e. other vultures using/having used the thermals) to find the next thermal updraft, especially in unfavourable flight conditions. Low-ranked individuals were more likely to disregard social cues when deciding where to go next, possibly to minimise the competitive risk of social aggregation. These results exemplify the architecture of decision-making during flight in social birds. It suggests that the environmental context, the context of risk and the social system as a whole calibrate the balance between personal and social information use.

animal behavior and cognition↗

bioRxiv2023

Cities as parasitic burden? Malaria prevalence and diversity along an urbanization gradient in great tits

Urbanization is a worldwide phenomenon that modifies the environment. By affecting the reservoirs of pathogens and the body and immune conditions of hosts, urbanization alters the epidemiological dynamics and diversity of diseases. Cities could act as areas of pathogen dilution or amplification, depending on whether urban features have positive or negative effects on vectors and hosts. In this study, we focused on a host species and investigated the prevalence and diversity of avian malaria parasites (Plasmodium/Haemoproteus sp. and Leucocytozoon sp.) in great tits (Parus major) living across an urbanization gradient. In general, we observed high prevalence in adult birds (from 95% to 100%), yet lower prevalence in fledglings (from 0% to 38%). We found a slight tendency for increased Plasmodium sp. prevalence with increasing urbanization in adults. Urban nestlings had higher Plasmodium sp. infection rates than non-urban nestlings. We found evidence of higher diversity of parasites in the most natural urban park; however, parasite diversity was similar across other urbanization levels (e.g. from a little artificialized park to a highly anthropized industrial area). Parasite lineages were not habitat specific. Only one Plasmodium sp. lineage (YWT4) was associated with urban areas and some rare lineages (e.g., AFR065) were present only in a zoo area, perhaps because of the presence of African birds. This study suggests that urbanization can lead to a parasite amplification effect and can favor different avian malaria lineages.

ecology↗

bioRxiv2022

Species sympatry shapes brain size evolution in Primates

The main hypotheses on the evolution of animal cognition emphasise the role of conspecifics in affecting the socio-ecological environment shaping cognition. Yet, space is often simultaneously occupied by multiple species from the same ecological guild. These sympatric species can compete for food, which may thereby stimulate or hamper cognition. Considering brain size as a proxy for cognition, we tested whether species sympatry impacted the evolution of cognition in frugivorous primates. We first retraced the evolutionary history of sympatry between frugivorous primate lineages. We then fitted phylogenetic models of the evolution of the size of several brain regions in frugivorous primates, considering or not species sympatry. We found that the evolution of the whole brain or brain regions used in immediate information processing was best fitted with models not considering sympatry. By contrast, models considering species sympatry best predicted the evolution of brain regions related to long-term memory of interactions with the socio-ecological environment, with a decrease in their size the higher the sympatry. We speculate that species sympatry, by generating intense food depletion, might lead to an over-complexification of resource spatiotemporality that counteracts the benefits of high cognitive abilities and/or might drive niche partitioning and specialisation, thereby inducing lower brain region sizes. In addition, we reported that primate species in sympatry diversify more slowly. This comparative study suggests that species sympatry significantly contributes to shaping primate evolution.

ecology↗