Our long-term monitoring programme of a wild roe deer population is based in the hills of the Coteaux et Vallons de Gascogne in the canton of Aurignac, south-west France. It is a heterogeneous agricultural landscape of around 12000 ha where the remaining woodland is fragmented and the landscape structure varies locally. We have conducted an annual capture-mark-recapture exercise on this hunted population since 2001 using a number of catch sites which vary in local habitat composition, allowing us to compare behavioural tactics across a gradient of landscape openness. We have caught well over 700 individual deer in total, and released the majority with a GPS (Global Positionning System) collar to track their movement behavior at small (daily activity) and large (dispersal) spatial scales. We take blood, fecal and hair samples to generate data on health, diet, and genetics. We also catch fawns during spring to study the early life stage which is so critical for understanding the population dynamics of large herbivores. We use proximity sensors to provide information on mother-young relationships, and we carry out direct observations to describe individual behavioural traits (vigilance, flight initiation distance, gregariousness, etc.) and to estimate reproductive success.  Much of the work involves understanding how landscape structure influences behaviour (e.g. the resource acquisition-risk avoidance trade-off) so we annually maintain an exhaustive GIS (Global Information System) of the study site describing changes in land use and agricultural and sylvicultural practices. Lastly, we study the impacts of this large herbivore on its ecosystem (ecosystem engineer sensu Jones et al. 1997, Ecology 78: 1946-57) by consuming vegetation and transferring seeds, nutrients and pathogens between landscape compartments.