Wild Carrion Crows (Corvus corone) Autonomously Respond to Speech but Show No Difference in Their Response to a Local and a Foreign Language

Abstract

Eavesdropping on the vocalizations of other species can be beneficial for wildlife to avoid predator encounters, including encounters with humans. Wild-caught large-billed crows in Tokyo responded more to playback of a foreign language than to Japanese without any training or rewards provided in the experiment, suggesting habituation to the local language. Here I tested the response of wild carrion crows in the UK to playback of a foreign language (Vietnamese), the local language (English), and non-speech control vocalizations (pigeon and parakeet vocalizations) to examine whether wild crows eavesdrop on speech. Playback experiments were conducted in two cities that differ in their population size and linguistic diversity (London and Milton Keynes, Buckinghamshire), to understand the role of exposure frequency to humans and to different languages in their response to speech. The crows autonomously responded with increased flight behaviors to human speech compared to non-speech control vocalizations. However, unlike previously shown for large-billed crows, the carrion crows did not respond differently to the two languages. It remains to be understood whether eavesdropping on speech provides any benefit to the animals, particularly urban individuals with frequent exposure to humans.