The secretary bird (Sagittarius serpentarius) is the only member of the family Sagittariidae. This family is part of the Accipitriformes, which includes other hawk-like raptors such as hawks, eagles, vultures, kites, falcons, and the osprey.
The secretary bird is native to sub-Saharan Africa, and occurs in open grasslands and savannas. The species is wide-ranging, and some populations are nomadic, wandering extensively in search of locations with large populations of small mammals or insects, their principal foods.
Secretary birds are large birds, standing as tall as 4 ft (1.2 m), and weighing about 9 lb (4 kg). Their wings are long and pointed, and the neck is long. Secretary birds have a strong, hooked, raptorial beak, and a prominent crest on the back of their heads. The legs are very long, and the strong feet have sharp, curved claws.
The basic coloration of secretary birds is gray, with black feathers on the upper legs, on the trailing half of the wings, and on the base of the tail. Two long, central, black-tipped feathers extend from the base of the tail. There are bare, orange-colored patches of skin around the eyes. The sexes are similarly colored, but male secretary birds are slightly larger.
Secretary birds are believed to have received their common name after the feathers of their backward-pointing crest, which are thought to vaguely resemble quill-pens stuck into the woolly wig of a human scribe of the nineteenth century. Their erect posture and grey-and-black plumage is also thought to suggest the formal attire and demeanor of a human secretary.
Secretary birds hunt during the day, mostly by walking deliberately about to find prey, which when discovered are run down and captured. Secretary birds occasionally stamp the ground with their feet, to cause prey to stir and reveal its presence. The food of secretary birds consists of small mammals, birds, reptiles, and large insects, such as grasshoppers and beetles. They are known to kill and eat snakes, including deadly poisonous ones, which like other larger prey items are dexterously battered to death with the feet. Because of their occasional snake-killing propensities, secretary birds are highly regarded by some people.
Secretary birds can fly well, and sometimes soar, but they do not do so very often. They prefer to run while hunting, and to escape from their own dangers. They roost in trees at night, commonly in pairs.
Secretary birds are territorial. They build a bulky, flat nest of twigs in a thorny tree, which may be used for several years. Secretary birds lay 2-3 eggs. These are incubated by both sexes, which also share the duties of caring for the young. The babies are downy and feeble at birth. The young are initially fed directly with nutritious, regurgitated fluids, and later on with solid foods that are regurgitated onto the nest, for the young to feed themselves with. Young secretary birds do not fight with each other, unlike the young of many other species of raptors. Consequently, several offspring may be raised from the same brood. They typically fledge after about two months.
Secretary birds are commonly considered to be a beneficial species, because they eat large numbers of potentially injurious small mammals, insects, and to a lesser degree, snakes. Secretary birds are sometimes kept as pets, partly because they will kill large numbers of small mammals and snakes around the home. Unfortunately, the populations of these birds are declining in many areas, due largely to habitat changes, but also to excessive collecting of the eggs and young.