Maternal androgens increase sibling aggression, dominance, and competitive ability in the siblicidal black-legged kittiwake (Rissa tridactyla).
Animals and plants routinely produce more offspring than they can afford to rear.Mothers can favour certain young by conferring on them competitive advantages such as a leading position in the birth sequence, more resources or hormones.Avian mothers create hatching asynchrony within a clutch and at the same time bestow the eggs with different conce