Innovative flavoring behavior in Goffin's cockatoos

Abstract

Dunking behavior can be a foraging innovation in non-human animals in which food is dipped in a medium prior to consumption.¹ Five functions of this behavior have previously been suggested (soaking, cleaning, flavoring, drowning, and transporting liquid).^{2,3,4,5,6,7,8} Although experimental reports exist,^1,5,9,10,11 most dunking observations are anecdotal,¹² 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.¹³ 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.^3,14 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,¹³ 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.

Keywords: dunking; food preparation; foraging; innovation; seasoning.

Figure 1. The total dunking events over all breakfast sessions per subject

The upper panel shows the dunking events with noodles as food and the lower for potatoes. The color represents the medium that the food was dunked in. The significances of the individual preferences (binomial test) are represented with: p < 0.1, * p < 0.05, ** p < 0.01, *** p < 0.001. See also Figures S1–S4, Table S1, and Videos S1, S2, and S5.

Figure 2. The median time the food was left in the medium for yogurt dunking versus rusk soaking

These boxplots show the dunking times (s) for this study in yogurt and for the previous study in water. Each dot represents an individual, with some horizontal variation for the visualization. The boxplots present the median and interquartile ranges. p value is represented with * p < 0.05, ** p < 0.01, *** p < 0.001.

Figure 3. Food and color preferences for each individual

The food choices made during the food preference test are shown for the noodles (A) and the potato pieces (B). The significance shows whether the individual had a significant preference or dislike for the combination (“both”). The color choices made during the color preferences are shown in (C). The color represents the choice made. The dotted lines represent the chance levels (1/3 for food choice, 1/2 for color choice). The significances of the individual preferences (binomial tests) are represented with: p < 0.1, * p < 0.05, ** p < 0.01, *** p < 0.001. See also Videos S3 and S4.