Brief
Researchers document blood‑drinking finches on Galápagos islands
A team led by Daniel Baldassarre filmed vampire ground finches piercing Nazca boobies for blood on Wolf and Darwin islands.
By Felo News Desk · Published
During a recent field expedition to the remote Galápagos islands of Wolf and Darwin, zoologist Daniel Baldassarre and two colleagues observed vampire ground finches feeding on the blood of Nazca boobies, according to a report in Popular Science.
What happened
The researchers reached the cliffs of the islands by dinghy, waiting for a lull in the waves before hopping onto sharp lava rocks. While on site, they saw the finches repeatedly clambering over the backs, tails and wings of the boobies, opening wounds with their sharp beaks and drinking the blood that flowed. The team recorded the birds’ blood‑stained bills and throats visibly engorged with blood.
What the reports add
Popular Science notes that the finches’ diet is opportunistic: unpublished data collected by Baldassarre’s team suggest that blood accounts for roughly one‑tenth of their overall intake, with the remainder consisting of seeds, insects and broken seabird eggs. The article also cites Baldassarre’s explanation that blood may serve as a water source in the islands’ extremely dry environment, where freshwater is scarce.
What was said
"Blood is a notoriously difficult food source to process and extract nutrients from, which probably partly explains why so few animals have evolved to feed on it," Baldassarre told Popular Science. He added, "These finches are quite opportunistic, so they will eat just about anything they can find."
How it came about
The researchers suggest that the finches’ relationship with the boobies likely began as a cleaning mutualism, with the birds picking parasites off the seabirds’ feathers. Over evolutionary time, the finches may have started to create lesions while removing parasites, eventually turning the interaction into blood feeding. Their bills have become more scalpel‑like, suited to making precise incisions.
Key facts
- Vampire ground finches were observed feeding on Nazca boobies on Wolf and Darwin islands. (popsci.com)
- Blood makes up about ten percent of the finches' diet, according to unpublished data. (popsci.com)
- Researchers propose the behavior evolved from a parasite‑cleaning relationship. (popsci.com)
Sources
- [1] popsci.com — originally reported as “Real-life vampire birds hunt and drink blood in remote Ecuador”
