The act of a bird preying upon another bird is known as avivory, a specialized dietary strategy found across a surprising number of avian orders. This behavior is not limited to the large, powerful raptors, but is practiced by species ranging from tiny songbirds to large seabirds. Avian avivores require unique physical and behavioral adaptations, employing specialized tools such as sharp talons, powerful beaks, and exceptional eyesight to catch their agile prey.
The Specialized Hunters
The most widely recognized avian avivores are the raptors, whose anatomy is specifically adapted for the pursuit and capture of other birds in flight or on the ground. Among the true hawks, or Accipiters, species like the Sharp-shinned Hawk and the Goshawk possess short, rounded wings and long tails. This particular morphology allows them to execute rapid, tight maneuvers, making them highly effective at ambushing and pursuing small birds within the dense cover of forests and shrubbery. They often rely on surprise, launching an explosive, short-distance burst of speed from a concealed perch.
Falcons, in contrast, are built for speed in open airspace, characterized by long, pointed wings that enable high-velocity flight. The Peregrine Falcon is the quintessential avian speed specialist, renowned for its “stoop,” a high-speed dive that can exceed 300 kilometers per hour (186 miles per hour). The falcon strikes its prey—usually other birds caught mid-air—with a clenched foot, often killing it instantly from the sheer force of the impact before circling back to retrieve the fallen body.
Nocturnal hunters such as the Great Horned Owl also engage in avivory, using their silent flight to their advantage. The fringed edges of their flight feathers muffle the sound of air passing over their wings, allowing them to approach roosting birds undetected. While many owls primarily hunt rodents, they will opportunistically prey on songbirds and even other raptors, relying on their acute hearing and low-light vision to locate vulnerable targets in the darkness.
Unexpected Avian Predators
Avivory is not exclusive to the traditional birds of prey, with many species from non-raptorial families regularly including other birds in their diet. Shrikes, sometimes called “butcher birds,” are passerines that exhibit a raptor-like hunting style, featuring a hooked beak and strong legs. These small yet ferocious hunters catch prey up to their own size, including small passerines like goldfinches, and famously impale their victims on thorns or barbed wire to store them for later consumption.
Corvids, a group known for their intelligence, including crows, ravens, and jays, are highly successful nest predators. They employ coordinated strategies to locate and consume the eggs and young of other bird species, utilizing their sharp eyesight and observation skills to track parents returning to their nests. Though they less frequently take healthy adult birds, their consistent raiding of nests represents a significant predatory pressure on songbird populations.
Large gulls, such as the Great Black-backed Gull, are opportunistic omnivores that frequently prey on other birds, particularly in coastal and colonial nesting environments. They are known for raiding the nests of smaller seabirds, taking eggs and nestlings, and will also kill small adult birds like puffins and storm-petrels. Even wading birds, like herons and egrets, occasionally display avivorous behavior by swallowing small birds whole, especially chicks or injured adults that venture too close to the water’s edge.
Hunting Strategies and Prey Selection
Avian predators employ distinct behavioral categories to secure their prey, methods that rely on different combinations of speed, stealth, and surprise.
Aerial Pursuit
This is the strategy of choice for fast-flying birds like falcons, involving a high-speed chase in open air. The pursuit culminates in a mid-air strike, demanding exceptional maneuverability and specialized wing shapes. These adaptations are necessary to maintain the speed and trajectory required to overtake another flying bird.
Ambush Hunting
This common method is utilized by Accipiters and many owls. The predator waits silently, often concealed in dense foliage or on a high perch, relying on the element of surprise for a successful capture. This technique involves a short, explosive dash or a silent glide, allowing the hunter to catch the prey before it can react or escape to safety.
Nest Predation and Raiding
This strategy focuses on targeting the most vulnerable life stages of other birds. Predators like corvids and gulls focus on eggs, chicks, or fledglings that are confined to a nest or are still learning to fly. This approach minimizes the energy expenditure and risk associated with pursuing a healthy adult bird, offering a reliable meal for the opportunistic avian hunter.