Data from: Decoding parrot duets: Complex communication in yellow-naped amazons

Parrots represent an excellent model in which to study complex vocal
communication because they meet the prerequisites of the social complexity
hypothesis and, like humans, have lifelong vocal learning. Despite that,
the difficulty in acquiring good field data on wild parrot vocalizations
has limited such research. Here, we examine the warble duets of the
yellow-naped amazon, a critically endangered species, which are used by
mated pairs when defending territories. We found that these duets are
marked by a large lexicon of 36 call types, with additional variants. The
calls also assort non-randomly within the duets and are organized by
syntactic rules. In addition, 58% of call types were sex specific, while
the remaining call types were used by both sexes and thus appeared to be
sex-neutral. Overall, the duets were marked by great variability; despite
being structured by syntactic rules, we observed very little overt
repetition in entire duets. This research provides important evidence that
large repertoires and complex vocal communication are an important part of
the natural communication systems of wild parrots.