Behavioural and morphological changes in the mallard and their relationship to plasma oestrogen concentrations.
D000818:Animals; D001522:Behavior, Animal; D004372:Ducks / Q000502:physiology*; D004958:Estradiol / Q000097:blood*; D005241:Feathers; D005260:Female; D008297:Male; D012621:Seasons; D012737:Sex Factors
D004958:Estradiol