Darwin’s small and medium ground finches might have taste preferences, but not for human foods

Abstract

Urbanization is rapidly changing ecological niches. On the Galapagos Islands, Darwin's finches consume human-introduced foods preferentially; however, it remains unclear why. Here we presented pastry with flavour profiles typical of human foods (oily, salty, sweet) to small and medium ground finches to test if latent taste preferences might drive selection of human foods. If human-food flavours were consumed more than a neutral or bitter control at sites with human foods, then we predicted tastes were acquired after experience with human foods; however, if no site-differences were found then this would indicate latent taste preferences. Contrary to both predictions, we found no evidence that human-food flavours were preferred compared to control flavours. Instead, medium ground finches consumed the bitter control pastry most and wiped their beaks more frequently after feeding on oily and sweet pastry (post-ingestion beak wiping can indicate aversions). Small ground finches showed no differences in consumption but wiped their beaks most after feeding on sweet pastry. Our results suggest that unlike many species, medium and small ground finches do not find bitter-tasting food aversive. Furthermore, taste preferences are unlikely to play a major role in Darwin's finches adaptation to the presence of human foods during increased urbanization.