American Vampire Finches

American vampire finches are a group of future descendants of Galapagos vampire finches that were genetically engineered to tolerate any land mammals, viruses, diseases, etc. They are now complete blood-suckers, with blood from birds and mammals being their main food sources, often drinking blood off of larger mammals like North American Neomastodons, predator dylanuses, American common dylanuses, etc, and birds like Hippostriches, groundbird, crows, parrots, bee-eaters, screaming pihas, etc.

Evolution
After the Late Holocene ended, humans are now gone, but many years before humans disappeared, humans had accidentally introduced genetically engineered Galapagos vampire finches into mainland North America, where they were causing plagues to some native and caused extinctions in some species like the brown and grizzly bears, which died during hibernations due to diseases that were spread by vampire finches. Over time, due to abundance of blood, vampire finch populations had exploded into tens of millions and over many years, diversified into hundreds of species with different types of colors. They also developed sharper beaks to pierce the skin of birds and mammals more efficiently. Galapagos vampire finches has evolved into American vampire finches.