Hematophagy is a feeding behavior in which an animal consumes the blood of another animal as a primary source of nutrition. It’s observed in various species–most notably, in vampire bats and mosquitoes.
It often reflects what biologists call a “parasitic relationship,” where one species’ benefit comes at the cost of another. Parasitic relationships can be contrasted with “symbiotic relationships,” where the actions of one species help themselves and the other species.
Here are four examples of “hematophagic,” or blood-sucking, birds. And, don’t worry—unless you live in the Galápagos Islands, Tristan da Cunha or sub-Saharan Africa, you won’t ever encounter them in the wild.
The Vampire Ground Finch (Geospiza septentrionalis)
The vampire finch, a small bird native to the Galápagos Islands (pretty much endemic to Wolf Island and Darwin Island), exhibits a fascinating form of hematophagy. Although it primarily feeds on seeds, fruits and insects, it has developed a unique behavior of occasionally drinking the blood of other birds, particularly the larger seabirds like the Nazca booby.
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The finch uses its sharp beak to peck at the skin of the seabird around the neck or back, puncturing blood vessels to access the blood. This feeding behavior is not widespread among all finches but is an adaptation that allows the vampire finch to obtain a liquid source of nutrition, particularly during times when other food sources are scarce.
The practice of blood-feeding in these birds is relatively rare and is considered parasitic. The finch doesn’t necessarily kill its host bird, but it can cause minor harm by inflicting wounds that may lead to blood loss or infection over time. This practice is thought to be a survival strategy in the harsh environment of the Galápagos Islands, where food can be unpredictable.
The interaction between the vampire finch and its host species is an example of a parasitic relationship, with the finch benefiting from the blood while the host bird experiences some level of harm, though the finch is not typically a significant threat to the host’s survival.
The Hood Mockingbird (Mimus macdonaldi)
The Hood mockingbird, also known as the Española mockingbird, is endemic to Española Island in the Galápagos. While it primarily has an omnivorous diet—feeding on insects, seeds, and fruits—it also engages in opportunistic hematophagy, feeding on blood when the opportunity arises.
Unlike the vampire finch, which relies more heavily on blood, Hood mockingbirds exhibit a more generalized opportunistic strategy—one that even makes them remarkably fearless of humans (watch the video below).
This 70-gram bird, often found in groups of 8 to 40, has been observed pecking at wounded animals, particularly seabirds like Galápagos petrels, to access their blood. Blood-feeding is most common during the breeding season or when food is scarce, making it a valuable supplementary resource.
Interestingly, there’s some evidence to suggest that these birds are far more “aggressive” than we once believed. On Española Island, some individuals do more than just peck at wounds to drink blood—they have been seen persistently pecking at the insensitive tail tips of large marine iguanas, removing centimeters of actual tissue in the process. This behavior exceeds typical reports of their opportunistic hematophagy, raising the possibility that some individuals engage in active tissue removal rather than just blood-feeding.
The Tristan Thrush (Turdus eremita)
The Tristan thrush, a near-threatened bird endemic to the Tristan da Cunha archipelago in the South Atlantic Ocean, exhibits an unusual form of hematophagy that distinguishes it from most other thrush species.
These birds are primarily insectivores, feeding on a wide variety of invertebrates, although they will “eat anything given the opportunity.” In keeping with their opportunistic nature, they have also been observed to engage in blood-feeding behavior, particularly when they feed on the wounds of seabirds, such as albatrosses.
These birds, locally known as starchies, are notorious for targeting the eggs of larger seabirds too, as seen at the very beginning of the video below—where one is observed preying on a yellow-nosed albatross egg.
The thrush uses its strong beak to peck at the exposed skin or wounds of the seabird, drinking the blood when the opportunity arises. This behavior is most commonly seen during the breeding season, when food may be scarce, and the thrush must exploit all available food sources.
Again, the practice of hematophagy in the Tristan thrush is considered a form of opportunistic parasitism, and not the bird’s primary means of sustenance. While the thrush does not typically cause significant harm to its host, repeated blood-feeding can weaken the affected seabirds over time, especially if they are already stressed or injured. The Tristan thrush’s use of blood as a supplemental food source reflects the challenges it faces in its remote and isolated habitat, where the availability of traditional food resources can fluctuate.
The Two Oxpecker Species (Buphagus africanus and Buphagus erythrorhynchus)
Oxpeckers are a well-known group of birds in sub-Saharan Africa that engage in a form of hematophagy by feeding on the blood of large herbivores, such as buffaloes, giraffes and rhinoceroses.
There are two species of oxpeckers: the yellow-billed oxpecker (Buphagus africanus) and the red-billed oxpecker (Buphagus erythrorhynchus). These birds are famous for their symbiotic relationship with their hosts, where they feed on ticks, dead skin and other parasites found on the skin of large mammals.
However, they also engage in blood-feeding by pecking at the wounds or injuries of their hosts (see cover image). The oxpecker may cause further harm by opening the wounds and drinking the blood, a behavior that has earned them a reputation for being parasitic.
Despite the negative connotations of their blood-feeding behavior, oxpeckers are also known to offer a beneficial service to their mammalian hosts by removing parasites. However, their practice of drinking blood can result in ongoing harm to the host animal, particularly if the oxpeckers keep the wounds open and continue to feed.
In some cases, oxpeckers have been observed to cause significant injury to their hosts by excessively pecking at their skin and encouraging the formation of new wounds. This behavior shows a complicated relationship between the oxpecker and its host—while it can provide parasite control, it also engages in parasitism through its hematophagous practices.
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