While in theory, ‘birds of prey’ could encompass almost all birds–there are two main traits that are looked at when deciding if a bird is a bird of prey or not, and they include:
The talons (or feet) for grasping or killing prey:
As you can see from the above picture–these predators all have feet, where the toes end in nice sharp talons:
Showing the size difference between different raptors–from one of the largest eagles (the harpy) down to the cosmopolitan peregrine falcon.
The second trait of birds of prey is having a powerful (and slightly curved) beak for tearing into the flesh (or crushing prey).
So here are some ‘semi-zoomed’ close-ups on the beaks of some birds of prey:
The ‘length’ of their beaks may vary–but they all end with the top being slightly curved over the bottom.
Therefore the birds of prey can be divided into the ‘diurnal’ (daytime) and ‘nocturnal’ (nighttime) birds of prey.
The ‘diurnal’ birds of prey include the orders: Falconiformes, Accipitriformes, and Cathartiiformes. These are the hawks, eagles, falcons, kites, New World Vultures, and other family members.
The ‘nocturnal’ birds of prey includes the single order: Strigiformes: the owls.
Currently I’ve managed to get a picture of at least one family member of each order, and the photography goals include getting a picture of a member on each continent, plus possibility of a youngster, or even a falcon, hawk, or eagle going in for the ‘kill’