page_title: Anti-exhaustion hypothesis
section_title: Anti-exhaustion hypothesis in blue tits
hierarchical_section_title: Anti-exhaustion hypothesis / Anti-exhaustion hypothesis in blue tits
caption_attribution_description: English: Eurasian blue tit, Cyanistes caeruleus, Lancashire, UK. Polski: Modraszka zwyczajna (Cyanistes caeruleus), Lancashire, Wielka Brytania.
context_page_description: The anti-exhaustion hypothesis is a possible explanation for the existence of large repertoires and the song switching behaviour exhibited in birds. This hypothesis states that muscle exhaustion occurring due to repeating song bouts can be avoided by switching to a different song in the bird's repertoire. The anti-exhaustion hypothesis therefore predicts that birds with larger repertoires are less susceptible to exhaustion because they can readily change the song that they are producing.
  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.
context_section_description: A study completed by  Angelika Poesel and Bart Kempenaers (2002) was aimed at explaining drift during blue tit (Cyanistes caeruleus) song and among other Parus species and to also explain their findings in relation to the anti-exhaustion hypothesis and the motivation hypothesis. They studied a group of 20 male blue tits at Kolbeterberg in Vienna, Austria that were living in mixed deciduous woods. The results from their study showed that male blue tits did show a decrease in performance output (percentage performance time) the longer that they performed one song typed, which was illustrated by an increase in inter-strophe pauses. 
  In order to confirm the anti-exhaustion hypothesis, the two factors proposed by Lambrechts and Dhondt that influenced a low percentage performance time needed to be confirmed. These two factors are the initial level of song output (the greater the initial output, the greater the drift would be), and the number of switches between song types (after a switch in song types, performance output was increased). The results from this study could conclude that a repeated stereotyped song is difficult to maintain over a long period of time, which supported the anti-exhaustive hypothesis.
caption: Fig. 2: Eurasian blue tit (Cyanistes caeruleus)
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