Circadian activity in different photoperiod (12L: 12 D) and (8L: 16D) in passerine finches

Circadian rhythms are more synchronized in birds than mammals. Circadian clock functions as a timing reference allow organisms fluctuations in their environments and are the basis for the transduction of seasonality from photoperiod. The present study was performed to determine the effect of constant dim and bright light illumination on circadian behavior of baya weaver bird (Ploceus philippinus), black-headed munia (Lonchura malaca malaca), and red-headed bunting (Emberiza bruniceps). It analyzed the data of locomotors activity of these under the effect of different photoperiods (12L: 12D and 8L: 16D) for a period of 30 days. In the captivity, birds were acclimatized for 4 weeks and were subjected to photoperiodic chambers (60×45×35 cm3) providing short-day conditions (8h light: 16h darkness; 8L:16D). Total activity profile was observed for 30 days under 12L: 12D and 8L: 16D photoperiod. Under 12 L: 12D photoperiod, significant response was observed in two of the four birds in daily profile of baya weaver bird and also in black-headed munia but the marginal significant response noticed in one of the four birds under 8L: 16D. The comparison of day and night total activity count in baya weaver bird and black-headed munia showed the maximum activity in weaver bird under 12L: 12D photoperiod.