Rescue of the traditional song culture of a critically endangered songbird.

Animal cultures are learned behaviours that are maintained in populations through social learning and conformity. Global reductions in species’ populations can lead to the loss of animal cultures, which may further reduce individual fitness. The Critically Endangered regent honeyeater (Anthochaera phrygia) is an Australian songbird whose population is declining to the extent that individuals have insufficient contact with conspecifics to maintain their song culture. Zoo-bred males that supplement the wild population sing songs that differ from all wild birds, representing a cultural barrier that may impact their fitness post-release. Over three breeding seasons within the applied breeding system, we undertook adaptive song tutoring experiments using song playback and live tutoring to teach zoo-bred juveniles the wild song. The proportion of juveniles that learned the wild song increased from zero to 42% within three years. The full version of the wild song taught to zoo-bred males disappeared from the wild during the study, making the zoo population the only remaining source of traditional song culture. Using just two wild founders, we show how animal cultures can be restored in ex-situ populations with simple modifications to husbandry protocols. Ex-situ populations could then help maintain and restore wild animal cultures through reintroductions.