Humans discriminate individual large-billed crows and individual cats by their respective vocalizations

Previous research has shown that human adults can easily discriminate two individual zebra finches (Taeniopygia guttata) by their signature songs, struggle to discriminate two individual rhesus monkeys (Macaca mulatta) by their calls, and are unable to discriminate two individual dogs (Canis familiaris) by their barks. The purpose of the present experiment was to examine whether acoustic discrimination of individual non-primate heterospecifics is limited to species producing stereotyped signature songs, or whether it is possible with the vocalizations of other species as well. This was tested here with the calls of individual large-billed crows (Corvus macrorhynchos) and the meows of individual domestic cats (Felis catus) using a forced-choice Same-Different Paradigm. Results show a high discrimination accuracy without prior training, although the scores obtained here for both species were lower than those in the zebra finch discrimination task. Discrimination accuracy of cat voices decreased when mean pitch was equalized between individuals, but was still possible without this cue. The removal of formant frequencies did not influence the discrimination, and there was no significant performance improvement across trials. These experiments suggest that individual acoustic discrimination is possible not only with species producing signature songs, but also with unlearned vocalizations of both birds and non-human mammals.