Biology subjects

Clermont, J.

Publications and source records attributed to Clermont, J..

8 recordsLinked to original sources

bioRxiv2026

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

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.

animal behavior and cognition↗

bioRxiv2025

Predicting space use patterns of a territorial top predator: from individual movement decisions to Arctic fox space use

O_LIPredicting animal space use could greatly improve our understanding and forecasting of ecological processes. Despite growing interest, the development of predictive space use models amenable to the integration of spatial processes into ecological frameworks have yet to reach their full potential. C_LIO_LIUsing high-resolution tracking data collected at 4-minute intervals from 26 Arctic foxes over five years, we developed a predictive space use model based on a step-selection approach. We assessed fine-scale habitat selection in relation to prey distribution, landscape features, and ecological constraints such as central place foraging and territoriality. We then used these results to build an agent-based model simulating fox space use and evaluated its ability to reproduce observed space use patterns. C_LIO_LIStep-selection analyses confirmed that fox movements were driven by habitat type, goose nest density, distance to den, and avoidance of distance to the home range boundary. Agent-based simulations closely matched empirical tracking data and accurately forecasted fox space use, even for individuals excluded from model parameterization. C_LIO_LIBy developing a predictive model of predator space-use, our study provides a foundation for incorporating additional components of the predation sequence and contributes to more spatially informed approaches in predator-prey ecology. C_LI

ecology↗

bioRxiv2024

Territoriality and resource availability modulate the effect of conspecific encounters on the foraging behaviours of a mammalian predator

The probability of encountering conspecifics shapes multiple dimensions of animal behaviour. For example, territorial individuals increase vigilance, scent marking and alarm calling when approaching home range boundaries. Whether territorial predators modify their foraging behaviours with respect to the probability of encountering neighbouring territory owners is poorly understood. However, this could strongly influence the landscape of predation risk and therefore modulate predator-prey interactions. We studied the movements and behaviours of 23 resident Arctic foxes occupying neighbouring home ranges during two years of contrasting resource availability (abundant resources in 2019, scarce resources in 2022) on Bylot Island, Nunavut, Canada. First, based on simultaneous GPS tracking of individuals, we established which individuals used a territory (an exclusive area) by estimating the spatial distribution of the probability of encountering a neighbour within their home range. Second, using GPS and accelerometry data, we evaluated if the probability of encountering a neighbour influenced the spatial distribution of foraging behaviours, and whether this relationship differed between territorial and non-territorial individuals. When resources were abundant, only breeding individuals excluded other foxes from a part of their home range and were thus territorial. When resources were rare, none of the foxes reproduced and all but one were territorial. Non-territorial individuals in 2019 were less likely to cache prey in areas with a high probability of encounter, possibly reducing the risk of cache pilfering. We found no effect of the probability of encounter on the behaviours of the non-territorial individual in 2022. The probability to cache prey of territorial individuals however did not depend on the probability of encountering a neighbour, suggesting they have no benefit of modulating the distribution of their caches according to potential encounters in a partly exclusive area. Our results thus suggest that Arctic foxes use different tactics to secure resources based on their degree of territoriality and the availability of resources. We highlight how the presence of resident, but non-territorial predators, whose home ranges overlap those of their territorial neighbours, may influence the distribution of predation risk by creating zones where predator density is high, potentially influencing predator-prey interactions.

ecology↗

bioRxiv2024

Perceived and observed biases within scientific communities: a case study in movement ecology

Who conducts biological research, where, and how the results are disseminated varies among geographies and identities. Identifying and documenting these forms of bias by research communities is a critical first step towards addressing them. We documented perceived and observed biases in movement ecology. Movement ecology is a rapidly expanding sub-discipline of biology, which is strongly underpinned by fieldwork and technology use. First, we surveyed attendees of an international conference, and discussed the results at the conference (comparing uninformed vs informed perceived bias). Although most researchers identified as bias-aware, only a subset of biases were discussed in conversation. Next, by considering author affiliations from publications in the journal Movement Ecology, we found among-country discrepancies between the country of the authors affiliation and study site location related to national economics. At the within-country scale, we found that race-gender identities of postgraduate biology researchers in the USA differed from national demographics. We discuss the role of potential specific causes for the emergence of bias in the sub-discipline, e.g. parachute-science or accessibility to fieldwork. Undertaking data-driven analysis of bias within research sub-disciplines can help identify specific barriers and first steps towards the inclusion of a greater diversity of participants in the scientific process.

ecology↗

bioRxiv2022

Predator-mediated interactions through changes in predator home range size can lead to prey local exclusion

1The effects of indirect biotic interactions on species occurrence are difficult to quantify in the wild. In theory, the exclusion of a prey species can occur through the numerical and functional responses of a predator to another prey. Few studies assessed the relative effects of these responses on the net interaction strength between multiple prey sharing common predators, in part because empirically based multi-species functional response models are very rare. To investigate whether the presence of a prey species affects predation rates and population growth rate of another prey species, we used a multi-prey mechanistic model of predation along with a population matrix model. The predation model was parameterized using a combination of behavioral, demographic, and experimental data acquired in an arctic vertebrate community. It includes the arctic fox (Vulpes lagopus), a predator feeding primarily on small mammals as well as eggs of various bird species such as sandpipers and colonial nesting geese. Our results showed that the positive effects of the presence of a goose colony on sandpiper nesting success (due to the handling time of goose eggs by the predator) were outweighed by the negative effect of an increase in fox density. The numerical response of the arctic fox was driven by a reduction in home range size in the goose colony. As a result, the net interaction from the presence of geese was negative. Our results also showed that this interaction could lead to local exclusion of sandpipers over a range of adult sandpiper annual survival observed in the wild, which is coherent with previous observations of their co-distribution. Our approach takes into account diverse proximate mechanisms underpinning interaction strengths in a multi-prey system and generates novel insights on some of the predator behavioral responses that may influence prey coexistence (and the lack of) in vertebrate communities.

ecology↗

bioRxiv2021

Multi-species mechanistic model of functional response provides new insights into predator-mediated interactions in a vertebrate community

1.AO_SCPLOWBSTRACTC_SCPLOWPrey handling processes are considered a key driver of short-term positive indirect effects between prey sharing the same predator. However, a growing body of research indicates that predators are rarely limited by such processes in the wild. Density-dependent changes in predator foraging be-havior can also generate positive indirect effects but they are rarely included as explicit functions of prey densities in functional response models. With the aim of untangling proximate drivers of species interactions in natural communities and improve our ability to quantify interaction strength, we extended the Holling multi-species model by including density-dependent changes in predator foraging behavior. Our model, based on species traits and behavior, was inspired by the verte-brate community of the arctic tundra, where the main predator (the arctic fox) is an active forager feeding primarily on cyclic small rodent (lemming) populations and eggs of various tundra-nesting bird species. Short-term positive indirect effects of lemmings on birds have been documented over the circumpolar Arctic but the underlying proximate mechanisms remain poorly known. We used a unique data set, containing high-frequency GPS tracking, accelerometer, behavioral, and experimental data to parameterize the multi-species model, and a 15-year time series of prey densities and bird nesting success to evaluate inter-action strength between species. Our results showed that: (i) prey handling processes play a minor role in our system and (ii) density-dependent changes in predator foraging behavior can be the proximate drivers of a predominant predator-mediated interaction observed in the arctic tundra. Mechanisms outlined in our study have been little studied and may play a significant role in natural systems. We hope that our study will provide a useful starting point to build mechanistic models of predation, and we think that our approach could conceivably be applied to a broad range of food webs.

ecology↗

bioRxiv2020

Derivation of predator functional responses using a mechanistic approach in a natural system

The functional response is central to our understanding of any predator-prey system as it establishes the link between trophic levels. Most functional responses are evaluated using phenomenological models linking predator acquisition rate and prey density. However, our ability to measure functional responses using such an approach is often limited in natural systems and the use of inaccurate functions can profoundly affect the outcomes of population and community models. Here, we develop a mechanistic model based on extensive data to assess the functional response of a generalist predator, the arctic fox (Vulpes lagopus), to various tundra prey species (lemmings and the nests of geese, passerines and sandpipers). We found that predator acquisition rates derived from the mechanistic model were consistent with field observations. Although sigmoidal functional responses were previously used to model fox-prey population dynamics, none of our simulations resulted in a saturating response in all prey species. Our results highlight the importance of predator searching components in predator-prey interactions, especially predator speed, while predator acquisition rates were not limited by handling processes. By combining theory with field observations, our study provides evidences that predator acquisition rate is not systematically limited at the highest prey densities observed in a natural system. We reinforce the idea that functional response categories, typically types I, II, and III, should be considered as particular cases along a continuum. Specific functions derived with a mechanistic approach for a range of densities observed in natural communities should improve our ability to model and understand predator-prey systems.

ecology↗

bioRxiv2020

The predator activity landscape predicts the anti-predator behavior and distribution of prey in a tundra community

Predation shapes communities through consumptive and non-consumptive effects, where in the latter prey respond to perceived predation risk through risk management strategies occurring at different spatial and temporal scales. The landscape of fear concept is useful to better understand how predation risk affects prey behavioral decisions and distribution, and more generally the spatial dimension of predator-prey relationships. We assessed the effects of the predation risk landscape in a terrestrial Arctic community, where arctic fox is the main predator of ground-nesting bird species. Using high frequency GPS data, we developed a predator activity landscape resulting from fox space use patterns, and validated with an artificial prey experiment that it generated a predation risk landscape. We then investigated the effects of the fox activity landscape on multiple prey, by assessing the anti-predator behavior of a primary prey (snow goose) and the nest distribution of several incidental prey. Areas highly used by foxes were associated with a stronger level of nest defense by snow geese. We further found a lower probability of occurrence of incidental prey nests in areas highly used by foxes, but only for species nesting in habitats easily accessible to foxes. Species nesting in refuges consisting of micro-habitats limiting fox accessibility, like islets, did not respond to the fox activity landscape. Consistent with the scale of the fox activity landscape, this result reflected the capacity of refuges to allow bird nesting without regard to predation risk in the surrounding area. We demonstrated the value of using predator space use patterns to infer spatial variation in predation risk and better understand its effects on prey in landscape of fear studies. We also exposed the diversity of prey risk management strategies, hence refining our understanding of the mechanisms driving species distribution and community structure.

ecology↗