Evidence for vocal signatures and voice-prints in a wild parrot

In humans, identity is partly encoded in a voice-print that is carried across multiple vocalisations. Other species also signal vocal identity in calls, such as shown in the contact call of parrots. However, it remains unclear to what extent other call types in parrots are individually distinct, and whether there is an analogous voice-print across calls. Here we test if an individual signal is present in other call types, how stable this signal is, and if parrots exhibit voice-prints across call types. We recorded 5599 vocalisations from 229 individually-marked monk parakeets (Myiopsitta monachus) over a two year period in Barcelona, Spain. We find evidence for an individual signal in three out of five call types. We further show that while contact calls are individually distinct, they are more variable within individuals than previously assumed, changing over short time scales (seconds to minutes). Finally, we provide evidence for voice-prints across multiple call types, with a discriminant function being able to predict caller identity across call types. This suggests that monk parakeets may be able to use vocal cues to recognise conspecifics, even across vocalisation types and without necessarily needing active vocal signals of identity.