[The infradian rhythm in changes of thyroxine level and related periodicity of feather replacement during the molting in passerine birds].

Abstract

In the course of 15 days, the thyroxine and corticosterone level was measured daily in blood serum of molting starlings, Sturnus vulgaris, by use of enzyme immunodetection method. Revealed are three-day rhythm in changes of thyroxine level and four-day one in changes of corticosterone level, both rhythms being synchronized in different birds. A beginning of growth of new oar feathers coincides with maximum thyroxine concentration in blood serum and also demonstrates a three-day period. In free-living passerine birds (Passer montamus, Parus major, Chloris chloris) a three-day rhythm is found in the dynamics of feather replacement. This rhythm is manifested synchronously in the studied species that differ in timing of post-nuptial molting. Established is the synchronous manifestation of three-day rhythm in changes of thyroxine level and feather replacement during molting in different passerine species and different birds of the same species.