Raptors

Variations in shape and size:

Three orders. Two diurnal, one nocturnal.

Diurnal and nocturnal groupings.

Nocturnal: separate order -- two extant families of the order Strigiformes.

• Strigidae: "typical owls"
• Tytonidae: barn and bay owls

Diurnal: two orders --

• Order: Falconiformes --
• Family: Falconidae
• Subfamilies (2):
• Falconinae: falcons, kestrels, falconets
• Polyborinae: caracaras and forest falcons

• Order: Accipitriformes --
• Families:
• Sagittariidae: only one living species, the secretarybird (sic)
• Pandionidae: only one genus, the ospreys (Pandion)
• Accipitridae (Latin for hawk): 
• fourteen subfamilies:
• hawks, eagles, kites, harriers and Old World vultures
• of the fourteen, those that are most common:
• Accipitrinae: true hawks
• Buteoninae: broad-winged hawks; true eagles and sea eagles; western red-tailed hawk;
• Haliaeetinae: sea eagle, erne, ern
• Circinae: harriers

So, for raptors we have:

Diurnal and nocturnal.

Nocturnal: one group (owls) but there are two families of owls

Diurnal: three groups in two orders --

• Order Falconiformes: falcons/kestrels; 
• Order Accipitriforme: 
• secretarybird (Africa); and, 
• everything else (broad-winged; generally large)

Everything else:

• hawks, eagles, kites, ospreys, sea eagles, harriers

In a way, one can divide the raptors into the following four groups:

• owls
• secretarybird (Africa, ignore)
• falcons
• hawks, eagles, kites, harriers