Photoperiodic time measurement and photoentrainment of a circadian locomotor activity rhythm in subtropical tree sparrows

Circadian versus circannual rhythm in the photoperiodic programming of seasonal responses in Eurasian tree sparrow (Passer montanus)

Experiments were done on the subtropical tree sparrow to examine whether day length, as a proximate factor, involves circadian rhythm in timing seasonal responses or these events are programmed by the mediation of endogenous circannual rhythm.