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.