Circannual rhythms in birds: their interaction with circadian rhythms and environmental photoperiod.
D000818:Animals; D001522:Behavior, Animal; D001717:Birds / Q000502:physiology*; D001835:Body Weight; D002940:Circadian Rhythm; D008027:Light; D008297:Male; D008954:Models, Biological; D010507:Periodicity; D012621:Seasons; D013737:Testis / Q000254:growth & development