Innovative flavoring behavior in Goffin's cockatoos.

Dunking behavior can be a foraging innovation in non-human animals in which food is dipped in a medium prior to consumption. Five functions of this behavior have previously been suggested (soaking, cleaning, flavoring, drowning, and transporting liquid). Although experimental reports exist, most dunking observations are anecdotal, making it hard to infer its function. Previously, we reported innovative dunking behavior in a group of Goffin's cockatoos (Cacatua goffiniana) with the apparent function of soaking dry food. Here, we report cockatoos dunking in soy yogurt with the likely function of flavoring their food, something thus far only observationally reported in Japanese macaques. In an experimental setup with two types of soy yogurt and water, 9 out of 18 cockatoos dragged food through yogurt, with an overall preference for blueberry-flavored yogurt over neutral yogurt, which could not be explained by color preference alone. Furthermore, the cockatoos showed an overall preference for the combination of yogurt and noodles in a separate food preference task. This combination of quantitative and qualitative results indicates that the cockatoos use yogurt to flavor their food, preferring this combination rather than the yogurt flavor alone. Considering that not all cockatoos dunk their food in yogurt, and little overlap in individuals dunking in a previous study, this suggests a second food preparation innovation in this species. Our results thus provide experimental evidence of innovative food flavoring behavior outside the primate lineage, which may supplement our present understanding of the emergence of rare forms of food preparation behaviors in animals. VIDEO ABSTRACT.