The occurrence of Zugunruhe even in cage-raised birds with no environmental cues (e.g. shortening of day and falling temperature) has pointed to the role of circannual endogenous programs in controlling bird migrations.
A aparición do Zugunruhe incluso en aves criadas en gaiolas sen sinais ambientais (como o acurtamnto do día ou a baixada das temperaturas) indica o papel que xogan os programas endóxenos circanuais no control da migración das aves.