<P> if MH ≤ M, </P> <P> f H (\ displaystyle fH) is the parents' future reproductive success, if it makes no reproductive attempt . The parameter θ determines the relationship between parental investment and the cost of reproduction . The equation indicates that as M (\ displaystyle M) increases, the future reproductive success of the parent decreases . </P> <P> The probability p (m) that a chick joins the breeding population after receiving M units of PI is </P> <P> P (m) = 1 − M v / m (\ displaystyle P (m) = 1 - Mv / m) if m> m v (\ displaystyle m> mv) </P>

Siblicide is a common behaviour found in which antarctic seabird