From behaviour to demography: plasticity and interdependence of terrestrial large mammal responses to global changes in boreal environments

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Boreal forests were traditionally structured by natural disturbances (wildfires, windthrow, insect outbreaks), but anthropogenic footprint (habitat loss and fragmentation) became prevalent in the last decades, overriding natural disturbances and forcing wildlife to adapt to a rapidly changing environment. It is of prime importance to understand the impacts of both types of disturbances on species - habitat relationships, species interactions (predation, competition) and ultimately population fluctuations (expansion, decline). My research program aims at clarifying our understanding of the mechanisms by which disturbances influence animal ecology and at characterising the plasticity and interdependence of the responses observed. It is supported by a conceptual framework integrating the impacts of increasing disturbance severity along a succession of hierarchical biological levels ranging from behaviour and physiology to vital rates, population and community structure. The underlying hypotheses suggest that biological levels are interdependent and that behavioural plasticity among individuals could lead to different demographic outcomes and explain partially the variability in population resilience. For example, an animal could adjust its habitat selection to increasing levels of disturbances, up to a threshold above which behavioural adjustments are not possible and survival is compromised, resulting in a decrease in population abundance and individual performance. My work has been focused on understanding behavioural responses (space use, habitat selection) to human-induced disturbances (e.g. roads, logging). I recently began to establish links between behaviour and survival to illustrate the consequences of behavioural decisions on demography and to highlight the mechanisms at play (e.g. nonlinear functional responses). I am using woodland caribou, identified as an irreplaceable component of Canada's biodiversity, as a biological model. I further consider its major predators (wolf, black bear, coyote) and its main competitor (moose). I use GPS telemetry to describe behaviour and monitor survival on an individual basis along a gradient of disturbance intensity. Over the next 5-years phase, I will pursue my longitudinal telemetry monitoring of large mammals to study the relationships linking 1) behaviour to demography (survival, productivity) by adding movement and fidelity to space use and habitat selection, and 2) behaviour to physiology, using cortisol levels (proxy of chronic stress), while considering both intra- and interindividual variations in behaviour. I will also 3) seek ecological thresholds in response to disturbances and will 4) integrate the synergistic influence of climate to the cumulative impacts of natural and anthropogenic disturbances on behaviour and demography.