The goal of this project is to describe the behaviour of rats. To study this behaviour, we will resort to the use of wireless sensor networks, monitoring various quantities that yield important information to complement current knowledge on the behavioural repertoire of rats. The challenges we face include data acquisition and processing on the one hand, as rat-borne sensor nodes will need to be small enough not to interfere with the rats’ own activities, thus limiting the available memory and processing capabilities. Additionally, rats spend a significant amount of time underground, making data transmission and routing a very interesting challenge, for which we are currently developing novel strategies.