The “snake bird,” also known as the Anhinga, is an aquatic bird found in warmer regions globally, recognized for its distinctive long, slender neck and remarkable underwater swimming abilities. Its unique appearance and behavior highlight its specialized aquatic adaptations.
Physical Features and Nomenclature
It features a long, S-shaped neck, which contributes significantly to its common name, “snake bird,” as only its neck often appears above the water when swimming, resembling a serpent ready to strike. The bird also has a sharp, pointed bill, webbed feet, and dark plumage, often with striking silvery markings on its wings and upper back. Males typically display a glossy black-green body with white streaks, while females have a paler, buff-brown head and neck.
This bird’s scientific name is Anhinga anhinga, and it belongs to the darter family, Anhingidae. Beyond “snake bird,” it is also known by other common names such as “darter” or “water turkey,” the latter due to its long, fan-shaped tail that spreads out during flight. The word “Anhinga” originates from the Brazilian Tupi language, meaning “devil bird” or “snake bird.”
Habitat and Foraging
Anhingas typically inhabit shallow, slow-moving freshwater environments, including lakes, rivers, swamps, and marshes, particularly those with abundant vegetation. They are rarely found outside freshwater habitats, except during severe droughts, though they may nest along the edges of open bays and lakes. Their primary diet consists almost exclusively of fish, but they may also consume amphibians, aquatic invertebrates, and insects.
Their foraging technique is highly specialized; they hunt by spearing fish with their sharp bill while underwater, rather than catching them with their feet. Anhingas stalk their prey slowly underwater, using their webbed feet for propulsion. Their less buoyant bones and wettable feathers contribute to their unique underwater hunting strategy, allowing them to submerge their bodies almost entirely and maintain neutral buoyancy, making them stealthy predators. Once a fish is impaled, the Anhinga surfaces, often tossing the fish into the air to reorient and swallow it headfirst, preventing injury from spines.
Distinctive Habits
After swimming and fishing, they are frequently observed perching with their wings outstretched in a “spread-wing” posture. This behavior is necessary because their feathers are not as waterproof as those of many other waterbirds; they become saturated upon immersion, aiding diving but requiring drying afterward. The outstretched wings allow them to dry their plumage and absorb solar heat, which is important given their unusually low metabolic rates and high rates of body heat loss in water.
Anhingas often perch on branches or stumps over water, frequently in trees. While generally solitary when foraging, they may roost in groups and nest in colonies, sometimes alongside other waterbirds like herons and cormorants. They are typically quiet birds, but they do produce vocalizations such as clicks, rattles, croaks, and grunts, particularly when near the nest or during flight.