Gauzens, B.; Rosenbaum, B.; Kalinkat, G.; Boy, T.; Jochum, M.; Kortsch, S.; O'Gorman, E. J.; Brose, U.

Adaptative foraging behavior should promote species coexistence and biodiversity under climate change as predators are expected to maximize their energy intake, according to principles of optimal foraging theory. We test these assumptions using a dataset comprising 2,487 stomach contents of fish species across functional groups, feeding strategies, and prey availability in the environment over 12 years. Our results show that foraging shifts from trait-dependent prey selectivity to density dependence in warmer and more productive environments. This behavioral change leads to lower consumption efficiency as species shift away from their optimal trophic niche, undermining species persistence and biodiversity. By integrating this adaptive behavior into dynamic models, our study reveals that adaptive foraging yields higher risk profiles for ecosystems under global warming.