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

D Lever,K M Gotanda,L V Rush,R Thorogood

doi:10.1098/rsos.211198

Abstract

Urbanization is rapidly changing ecological niches. On the inhabited 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 and sweet) to small ground finches (Geospiza fuliginosa) and medium ground finches (Geospiza fortis) to test if latent taste preferences might drive the selection of human foods. If human food flavours were consumed more than a neutral or bitter control only at sites with human foods, then we predicted tastes were acquired after urbanization; however, if no site differences were found then this would indicate latent taste preferences. Contrary to both predictions, we found little evidence that human food flavours were preferred compared with control flavours at any site. Instead, finches showed a weak aversion to oily foods, but only at remote (no human foods present) sites. This was further supported by behavioural responses, with beak-wiping occurring more often at remote sites after finches tasted flavours associated with human foods. Our results suggest, therefore, that while Darwin's finches regularly exposed to human foods might have acquired a tolerance to human food flavours, latent taste preferences are unlikely to have played a major role in their dietary response to increased urbanization.

Highlights

We presented pastry with flavour profiles typical of human foods to small ground finches (Geospiza fuliginosa) and medium ground finches (Geospiza fortis) to test if latent taste preferences might drive the selection of human foods
If human food flavours were consumed more than a neutral or bitter control only at sites with human foods, we predicted tastes were acquired after urbanization; if no site differences were found this would indicate latent taste preferences
That while Darwin’s finches regularly exposed to human foods might have acquired a tolerance to human food flavours, latent taste preferences are unlikely to have played a major role in their dietary response to increased urbanization

Summary

Introduction

Organisms’ responses to these altered niches vary, with some birds, for example, adapting more readily to incorporate human foods into their diet, but even preferentially consuming them over native food sources [14,16,17,18,19] These differences in whether, and how, populations and species use human foods can have consequences for local adaptation [7,20] and potentially affect species divergence [21].

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Conclusion