Photoperiodicity in birds.
D000818:Animals; D001717:Birds / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D008027:Light; D007986:Luteinizing Hormone / Q000378:metabolism; D010507:Periodicity; D010786:Photoreceptor Cells; D012098:Reproduction
D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone