Diurnal rhythms and seasonal changes in the roosting behaviour of Indian myna Acridotheres tristis (Linnaeus)

Abstract

The present study deals with the awakening and roosting behaviour of mynas. In the annual cycle of these mynas, 3 distinct phases were noticed-the pre-breeding season (November-March), breeding season (April-July) and post-breeding season (August-October). The various roosting activities of mynas such as the time of waking up and calls, the time of arrival and departure of the first bird and up to the last bird, communal noise and the time of final settlement at the communal roost show a systematic diurnal and seasonal changes in relation to the times of sunset and sunrise (i.e. the light and dark periods of a 24h day). These changes were found to be consistent at all the roosts under observations and during all the years of the study. These changes seem to be governed by endogenous rhythms, which are slightly altered due to the endocrine secretions particularly in the breeding season and are also modified due to the adverse climatic conditions. © 1980 Indian Academy of Sciences.