Some species have evolved to store rather than consume food while availability is high, for consumption when food is scarce. The mechanisms that allow animals to retrieve widely scattered food stores has been explored, but comparatively little is known about the mechanisms that underpin the motivation to hoard food. This project experimentally addressed this knowledge gap this using two closely related bird species that live in social groups during winter when hoarding motivation is high: the food hoarding coal tit, Periparus ater, and the non-hoarding great tit, Parus major. To understand the evolution of hoarding motivation, we have to not only understand the environmental factors that control it (and hence the survival problem it evolved to solve), but we also need to understand how these environmental factors are translated into neural signals. Therefore, this project addresses the fundamental question of how novel behaviors evolve. Understanding the mechanisms that control hoarding motivation will provide insights into the evolution of this behaviour and test the hypothesis that it has evolved by building on the existing, widely-conserved appetite regulation system.