Ravens (Corvus corax) use conspecifics and heterospecifics to navigate risky foraging scenarios.

Abstract

Foraging animals need to balance the trade-off between the benefits of exploiting new resources and the unknown risks they entail. Changing environments are especially challenging, as this balance between risk and reward needs to be constantly reevaluated. One strategy animals, and in particular scavengers employ, is using conspecifics and heterospecifics as sources of information to access food. In this study, we focused on free-ranging ravens that habitually forage in a wildlife park together with heterospecifics (boars) and tested their responses to unfamiliar and unpredictable foraging situations. In the 2-sites experiment (E1), we presented them with a choice between an unfamiliar (new) and a familiar (old) foraging site; in the object experiment (E2), we presented them with an object, otherwise not seen in the wildlife park, positioned randomly next to 1 of the sites. In both experiments, we found that ravens delayed their initial approach until the boars reached the food. In E1, ravens took longer to approach the food; stole more food from conspecifics but visited in larger numbers at the new site compared with the old. In conclusion: they flexibly used others, including heterospecifics, as sources of knowledge and means to access food. In E2, the object had a stronger aversive effect at the old site than at the new site, suggesting that the effect of unpredictability is stronger in familiar environments, where it might cause an expectancy violation. Our findings highlight that the behavior toward conspecifics and heterospecifics should be considered when studying scavengers' adaptability to changing environments.