the anti-exhaustion hypothesis was first proposed by marcel lambrechts and andré dhondt in 1988 after they carried out a study using recordings from great tits, "parus major", during the dawn chorus. there have been several studies carried out in which results have contradicted the anti-exhaustion hypothesis. recent studies have shown that there is no evidence that the anti-exhaustion hypothesis is the cause of large repertoires in birds. since the proposal of the anti-exhaustion hypothesis, several hypotheses have been proposed to explain the existence of repertoires and song switching behaviour in birds, including the motivation hypothesis and the warm-up hypothesis.