Biologging wildlife behaviour and the seasonality of boreal food webs

The behavioural decision to be active or inactive represents a trade-off between the need to acquire energy and the costs associated with that acquirement. In seasonal environments, the relative costs and gains associated with activity can shift dramatically between winter, when temperatures are cold and resources are scarce, and summer, when temperatures are mild and resources are abundant. Despite the obvious link between activity and seasonality, studies of activity patterns over multi-seasonal time scales are surprisingly sparse, meaning we do not know how activity responds to environmental conditions and, in turn, how activity responses to environmental conditions influence population dynamics and species interactions. In this thesis, I use biologging to quantify how free-ranging animals adjust activity according to seasonal environmental variation, including air temperature and resource availability, and theoretical modelling to explore the ecological implications of these responses, including population dynamics and trophic interactions. I collected continuous behavioural data through direct observations and biologging technologies over four years on three interacting species - the North American red squirrel, snowshoe hare, and Canada lynx - within the highly seasonal northern boreal forest. Using direct observations for biologger calibration, I show that classifying low frequency accelerometer signatures to long duration behavioural states can be achieved with high accuracy allowing for long duration (weeks to months) recordings even in small mammals with high frequency movements. Combining accelerometric and acoustic biologging technologies on snowshoe hares highlights the complementarity of accelerometer quantification of activity states and acoustic determination of finer-scale details like chewing. I show that red squirrel activity is highly seasonal with a 3-fold decrease in activity from autumn to winter and that hares express subtle behavioural responses to moonlight conditions and are characterized by more seasonal constancy in activity patterns than red squirrels. Given the advances achieved recording behaviour over long time periods on free-ranging individuals, I use four years of accelerometer recordings on red squirrels to show that daily activity is highly predictable as an optimization of energetic and reproductive gain. Finally, I show how summer-to-winter differences in activity levels determines the seasonality of biomass production and loss, and thus population rates of increase, decrease, and stability. Through empirically-supported theoretical modelling, this thesis highlights the ecological importance of animal activity in seasonal environments, including its bottom-up regulation by environmental conditions and its contributions to populations dynamics and species interactions

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.