The public awareness of biodiversity loss is growing; however, citizens still engage in behaviours that are harmful to ecosystems, such as buying products shipped from across the world. Exploring the public’s understanding of biodiversity loss is fundamental to promoting behavioural change. To this purpose, we carried out two studies to test whether the psychological distance of biodiversity loss influences citizens’ shared ideas about biodiversity, depending on individuals’ contact with nature, and how this can influence conservation behaviours. Study 1 (n = 261) demonstrated that the public’s shared ideas are organised around two axes, one relating to psychological distance and contact with nature, and one concerning the level of specificity of the terms used. Study 2 (n = 178) confirmed that the perception of biodiversity loss as a distant threat is related to weaker engagement in pro-environmental behaviours. The findings are discussed in terms of their innovative theoretical contributions and their potential practical implications.