The Secretary Bird (Sagittarius serpentarius) is a large, distinctive bird of prey endemic to the open grasslands and savannas of sub-Saharan Africa. It is instantly recognizable by its impressive height, standing up to 1.3 meters tall on long, bare legs. The bird’s mostly pale grey plumage contrasts with black flight feathers and thighs, and it features a prominent crest of black-tipped feathers on the back of its head. This unique crown is said to resemble the quill pens 19th-century office workers tucked behind their ears, which is the origin story for its common name. Despite its resemblance to a crane or stork, the Secretary Bird is classified within the order Accipitriformes, making it a true raptor alongside eagles and hawks. It is the only member of its own family, Sagittariidae.
How and When the Secretary Bird Flies
The Secretary Bird is a capable flier, but it spends the vast majority of its time on the ground. Its flight mechanics differ from many other raptors, which primarily hunt from the air or tree perches. The bird typically takes to the air with a powerful, running takeoff, especially when needing to gain altitude.
Once airborne, the Secretary Bird is a strong flier with a wingspan that can exceed two meters. It frequently utilizes rising columns of warm air, known as thermals, to gain altitude and soar effortlessly. Soaring allows the bird to survey its large territory, which can span up to 70 square kilometers, and conserve energy during long-distance travel.
Flight is necessary for reaching its massive nests, which are constructed high up in the thorny canopies of acacia trees. The birds also use aerial displays, which involve undulating flight patterns and swoops, as part of their courtship ritual. While it can fly well, the bird prefers to flee danger or move short distances by running. In flight, its long legs trail behind it, giving it a distinctive silhouette.
Hunting Behavior and Ground Movement
The Secretary Bird’s primary mode of locomotion and hunting is walking. These birds are highly terrestrial, pacing across the savanna at an average speed of 2.5 to 3.0 kilometers per hour. They are dedicated hunters, capable of covering extensive distances, with estimates suggesting they can walk between 20 and 30 kilometers each day in search of prey.
Its ecological niche is as a solitary or paired ground predator of the open grasslands. The bird walks through the tall grass, often using its wings to help flush out hiding prey, such as insects, rodents, and small reptiles. Its most famous hunting technique involves dispatching prey, particularly venomous snakes, through rapid, repeated stomps.
During this strike, the bird uses its foot to deliver a swift, percussive blow to the prey’s head. Scientific study has shown that the force of a single strike can be equivalent to five times the bird’s body weight, delivered in a contact time of only 10 to 15 milliseconds. This short contact time requires exceptional visual targeting and neural control to immobilize the victim.
Anatomical Traits for a Walking Hunter
The Secretary Bird’s body plan is suited for its terrestrial hunting lifestyle. Its legs are the longest of any raptor species, providing the necessary reach and leverage for its powerful stomping strikes. The lower sections of the legs are covered in thick scales, which offer protection against the bites of venomous snakes during a confrontation.
Unlike most birds of prey, which possess strong, curved talons for grasping and tearing, the Secretary Bird has relatively short, blunt toes. These feet are built for walking and striking rather than seizing and holding prey. The bird relies entirely on the hard, flat sole of its foot to stun or kill its target. This specialized foot structure separates it from its more aerial raptor relatives.