Assortative mating in falcons: Do big females pair with big males?

Several raptors have been shown to mate assortatively, most commonly according to age, less often in relation to various linear measurements. This paper demonstrates positive assortative mating for winglength in three falcons: the Peregrine Falcon Falco peregrinus, Brown Falcon F. berigora and Nankeen Kestrel F. cenchroides. Because females showed greater variation in winglength than did males, larger females formed more dimorphic pairs than smaller females. The results suggest a possible link between assortative mating and dimorphism.