Persistence associated with extractive foraging explains variation in innovation in Darwin's finches

The capacity to create new behaviors is influenced by environmental factors such as foraging ecology, which can lead to phylogenetic variation in innovativeness. Alternatively, these differences may arise due to the selection of the underlying mechanisms, collaterally affecting innovativeness. To understand the evolutionary pathways that might enhance innovativeness, we examined the role of diet breadth and degree of extractive foraging, as well as a range of intervening cognitive and behavioral mechanisms (neophilia, neophobia, flexibility, motivation, and persistence). Darwin's finches are very suitable to this purpose: the clade is composed of closely related species that vary in their feeding habits and capacity to develop food innovations. Using a multi-access box, we conducted an interspecies comparison on innovative problem-solving between two diet specialists, extractive foragers (woodpecker and cactus finch), and two diet generalists, non-extractive foragers (small and medium ground finch). We predicted that if extractive foraging was associated with high innovativeness, variation would be best explained by species differences in persistence and motivation, whereas if diet generalism was the main driver, then variation would be due to differences in flexibility and responses to novelty. We found a faster capacity to innovate and a higher persistence for extractive foragers, suggesting that persistence might be adaptive to extractive foraging and only secondarily to innovation. Our findings also show that diet generalism and some variables linking it to innovation were unrelated to innovativeness and call for the development of joint experimental approaches that capture the diversity of factors giving rise to novel behaviors. Animals differ in their innovativeness or capacity to create new behaviors. Foraging ecology, including what foods animals eat and how they reach them, can directly or indirectly contribute to these differences. Darwin's finches are a group of closely related bird species that differ in their innovative potential. By comparing species with different foraging regimes, we found that the higher persistence required by diet specialist, extractive foragers (compared to generalist, non-extractive foragers) facilitates innovativeness.