Sexing by plumage is notoriously difficult in Peregrines but it is probably a female if you think it's on the big side. Females are 10-14cm larger and 450g-1kg heavier than the biggest males!The size of the eye may be helpful on a perched bird; this is much the same size in both sexes and therefore looks relatively larger in males.
This reversal of size difference between males and females occurs in 2 main groups of birds:
1. Those which have role reversal (males look after the nests) – like in Buttonquails, Jacanas and Phalaropes.
2. Aerial hunters – like Bobbies, Frigatebirds, Skuas, Owls and diurnal raptors.
Amongst this second group ,the difference is perhaps most marked in the larger raptors that hunt fast moving creatures. There seems to be some relationship in size linked with their feeding habit, but the exact reason for this size difference is uncertain. It is known that smaller males make more agile hunters and are better providers of food . Larger females are better at protecting the nest & coping with the stresses of motherhood.
The size difference between the sexes is greatest in raptors that eat birds and mammals, less in those that live mainly on insects and least in those that feed on carrion.
I always assumed Peregrines were pretty cosmopolitan in their feeding habits, but most populations feed almost exclusively on birds. A pretty nice way of keeping the feral pigeon population down.
eRic
[ Last edited by RUWright at 23/01/2011 01:03 ]
