In the context of the Dutch Environmental Act, we conduct a lot of field research into, for example, the presence of badgers or pine martens. We do this on the basis of visual observations, but also through investigating tracks and signs. The research involves looking for lodgings, tracks, foraging signs, hair in barbed wire, excrement, traffic victims, prints in snow and prey victims. Camera traps, footprint tunnels and infrared cameras are also used.