Biology subjects

Ossi, F.

Publications and source records attributed to Ossi, F..

6 recordsLinked to original sources

bioRxiv2026

Intra- and interspecific relationships of alpine ungulates reorganise along a wolf recolonisation gradient

Apex predators are recovering across many ecosystems after decades of decline, yet whether their return can restore ecological interactions disrupted by their loss remains poorly understood. Here, we used the ongoing recolonisation of grey wolves (Canis lupus) in the south-eastern Alps as a natural gradient of predator recovery to examine how predation risk and human disturbance shape relationships among red deer (Cervus elaphus), roe deer (Capreolus capreolus), and Alpine chamois (Rupicapra rupicapra). Across a gradient of time since wolf establishment, roe deer increasingly occupied sites without red deer, suggesting predator recovery alters relationships between prey species. Red deer also formed larger groups, consistent with a shift in collective behaviour under increased predation risk. Human disturbance also affected group formation in red deer and chamois. Together, these findings show that prey community structure can vary with wolf recovery, even in human-dominated landscapes, through altered associations among species and grouping within species.

ecology↗

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

Assessing bias and robustness of social network metrics using GPS based radio-telemetry data

O_LISocial network analysis of animal societies allows scientists to test hypotheses about social evolution, behaviour, dynamical processes, and transmission events such as the spread of disease. However, the accuracy of estimated social network metrics depends on the proportion of individuals sampled, actual sample size, and frequency of observations. Robustness of network metrics derived from a sample has thus far been examined through various simulation studies. However, simulated data do not necessarily reflect the nuances of real empirical data. C_LIO_LIWe used some of the largest available GPS telemetry relocation datasets from five species of ungulates characterised by different behavioural and ecological traits and living in distinct environmental contexts to study the bias and robustness of social network metrics. We introduced novel statistical methods to quantify the uncertainty in network metrics obtained from a partial population suited to autocorrelated data such as telemetry relocations. We analysed how social network metrics respond to down-sampling from the observed data and applied pre-network data permutation techniques, a bootstrapping approach, correlation, and regression analyses to assess the stability of network metrics when based on samples of a population. C_LIO_LIWe found that global network metrics like density remain robust when the sample size is lowered, whereas some local network metrics, such as eigenvector centrality, are entirely unreliable when a large proportion of the population is not monitored. We show how to construct confidence intervals around the point estimates of these metrics representing the uncertainty as a function of the number of nodes in the network. C_LIO_LIOur uncertainty estimates enable the statistical comparison of social network metrics under different conditions, such as analysing daily and seasonal changes in the density of a network. Despite the striking differences in the ecology and sociality among the five different ungulate species, the various social network metrics behave similarly under downsampling, suggesting that our approach can be applied to a wider range of species across vertebrates. Our methods can guide methodological decisions about animal social network research (e.g., sampling design and sample sizes) and allow more accurate ecological inferences from the available data. C_LI

animal behavior and cognition↗

bioRxiv2022

Food resources drive rodent population demography mediated by seasonality and inter-specific competition

O_LIAs fast reproducing species, rodents present proximate numerical responses to resource availability that have been assessed by experimental manipulation of food, with contrasting results. Other intrinsic and extrinsic factors, such as climate severity, species life cycles, and sympatry of potential competitors in the community, may interplay to modulate such responses, but their effects have rarely been evaluated ensemble. C_LIO_LIWe applied a niche-based approach to experimentally determine the effect of bottom-up (food availability) and top-down (climate severity) extrinsic factors, as well as intrinsic seasonal cycles, on rodent demography, also in presence of sympatry between species in the community. C_LIO_LITo this end, we live-trapped rodents at two latitudinal extremes of the boreal-temperate gradient (Italian Alps and Norway) deploying control/treatment designs of food manipulation. We applied a multistate open robust design model to estimate population patterns and survival rate. C_LIO_LIYellow-necked and wood mouse (Apodemus spp.) were sympatric with bank vole in Italy, while the latter was the only species trapped in Norway. At northern latitudes, where harsher climatic conditions occurred, vole survival was principally regulated by intrinsic seasonal cycles, with a positive effect of food also on population abundance. At southern latitudes, mice and voles exhibited asynchronous population patterns across seasons, with survival depending from seasonal cycles. When concentrated ad libitum food was experimentally provided, though, population size and survival of voles strongly decreased, while mice abundance benefited from food supplementation. C_LIO_LIOur results evidence that rodent demography is regulated by a combination of top-down (climate severity) and bottom-up (food availability) extrinsic factors, together with intrinsic seasonal ones. Moreover, we showed that the seasonal niche partitioning of mice and voles could be disrupted by availability of abundant resources that favour the demography of the more opportunistic Apodemus spp. at the expense of Myodes glareolus, suggesting competitive mechanisms. We conclude putting our results in the context of climate change, where shifts in vegetation productivity may affect the diversity of the rodent community via demographic effects. C_LI

ecology↗

bioRxiv2020

Experimental evidence of memory-based foraging decisions in a large wild mammal

Many animals restrict their movements to a characteristic home range. This pattern of constrained space-use is thought to result from the foraging benefits of memorizing the locations and quality of heterogeneously distributed resources. However, due to the confounding effects of sensory perception, the role of memory in home range movement behavior lacks unequivocal evidence in the wild. Here, we analyze the foraging decisions of a large mammal during a field resource manipulation experiment designed to disentangle the effects of memory and perception. Using a cognitive movement model, we demonstrate that roe deer (Capreolus capreolus) rely on memory, not perception, to track the spatio-temporal dynamics of resources within their home range. Our findings show a memory-based spatial transition model parametrized with experimental data can successfully be used to quantify cognitive processes and to predict how animals respond to resource heterogeneity in space and time.

ecology↗

bioRxiv2019

Movement and space-use responses of a large herbivore to experimental alteration of resource availability

The link between spatio-temporal resource patterns and movement behaviour is a key ecological process, however, limited experimental support has been produced at the home range scale. In this study, we analysed the spatial responses of a resident large herbivore (roe deer Capreolus capreolus) during an in situ manipulation of a concentrated food resource. Specifically, we experimentally altered feeding site accessibility to roe deer and recorded (for 25 animal-years) individual responses by GPS tracking. We found that, following the loss of their preferred resource, roe deer actively tracked resource dynamics leading to more exploratory movements, and larger, spatially-shifted home ranges. Then, we showed, for the first time experimentally, the importance of site fidelity in the maintenance of large mammal home ranges by demonstrating the return of individuals to their familiar, preferred resource despite the presence of alternate, equally-valuable food resources. This behaviour was modulated at the individual level, where roe deer characterised by a high preference for feeding sites exhibited more pronounced behavioural adjustments during the manipulation. Together, our results establish the connections between movement, space-use, individual preference, and the spatio-temporal pattern of resources in home ranging behaviour.

ecology↗