Pochard is a diving duck breeding across Europe, from Spain to Siberia, with a differential migration of the sexes (Carbone & Owen 1995). The species uses a variety of habitats and has a large range, but despite this apparent flexible ecology, the populations are strongly declining, and few studies have tackled the species’ habitat needs (Ponomarenko et al. 2021). Using tags with pressure (e.g. depth) recorders, we will be able to document the 3D habitat needs of breeding pochards.