Long-term maintenance and eventual extinction of preference for a mate's call in the female budgerigar

Auditory memory is crucial for mate recognition in birds and for long-term maintenance of pair bonds in monogamous species. Parrots, unlike the majority of birds, can imitate sounds into adulthood. During pair bond formation, male budgerigars, Melopsittacus undulatus, which are monogamous parrots, imitate the calls of females. This imitation results in convergence of the two calls. We examined whether and how long the auditory memory of a mate's call affects female behaviour in relation to pair bond maintenance in this vocally plastic species. Females were paired with a male and then separated, without auditory/visual stimulation from the mate. Females responded to the calls of their separated mates, which had been recorded prior to pair formation, significantly more than to a call from an unfamiliar male. These females continued to show a preference for their respective mates' calls at 1 and 2 months after separation, demonstrating that the auditory memory of the mate's call was retained for at least 1 month in the absence of stimulation from the mate. These results show that long-term auditory memory mediates the preferential response to a mate's call in female budgerigars. However, females ceased to prefer their mates' calls after 6 months of separation, indicating that the preference response of females is eventually extinguished. We discuss the possibility that the extinction of the preferential response may be explained by an underlying mechanism other than the decay of auditory memory. (C) 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.