Vampire Ground-Finch
Geospiza septentrionalis
A rarely-seen Galápagos finch restricted to the islands of Darwin and Wolf. These islands are usually visited only by divers, so few birders have a chance to see this species. It was formerly considered a subspecies of Sharp-beaked Ground-Finch, and it has a similarly-shaped sharp, thin bill with nearly straight edges. Bill is black on breeding male and dull orange on female and nonbreeding male. Male’s plumage is sooty-black; female is brown with paler underparts that are streaked with gray. Its ominous name comes from its occasional habit of drinking blood, which it extracts from other animals by pecking until the skin is broken.
Identification
The vampire finch is sexually dimorphic as typical for its genus, with the males being primarily black and the females grey with brown streaks. It has a lilting song on Wolf, a buzzing song on Darwin, and whistling calls on both islands; only on Wolf, a drawn-out, buzzing call is also uttered.
Taxonomy
- Scientific name
- Geospiza septentrionalis
- Authority
- Rothschild & Hartert, EJO, 1899
- Order
- Passeriformes
- Family
- Thraupidae
- Genus
- Geospiza
Range and habitat
- Migration
- Resident species
Behavior
This bird is most famous for its unusual diet. When alternative sources are scarce, the vampire finch occasionally feedsby drinking the blood of other birds, chiefly the Nazca and blue-footed boobies, pecking at their skin with their sharp beaks until blood is drawn. Curiously, the boobies do not offer much resistance against this. It has been theorized that this behavior evolved from the pecking behavior that the finch used to clean parasites from the plumage of the booby. The finches also feed on eggs, stealing them just after they are laid and rolling them (by pushing with their legs and using their beak as a pivot) into rocks until they break. Finally guano and leftover fish from other predators additionally serve as diet options. <p>Vampire ground finches drink more blood during dry seasons when seeds and other prey are scarce, resuming omnivorous predation when the rainy season begins. There were also significant variations in the intestinal microbial community structure. There was a clear separation between vampire ground finches and other finches. Vampire ground finch birds have intestinal microbial communities rich in peptostreptococcacea. Similarly, vampire bats also possess peptostreptococcacea in their gut flora.<p>More conventionally for birds, but still unusual among Geospiza, they also take nectar from Galápagos prickly pear (Opuntia echios var. gigantea) flowers, at least on Wolf Island. The reason for these peculiar feeding habits is the lack of fresh water on these birds' home islands. Nonetheless, the mainstay of their diet is made up from seeds and invertebrates, as in their congeners.
Conservation
The vampire finch is classified as vulnerable by the IUCN based on its very restricted distribution and the impact of invasive species in its habitat.
- Population trend
- stable
Photos
Distribution
Bird Calls
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