Darwin's finches, named after Charles Darwin, are a group of 17 species endemic to the Galapagos Islands, with an additional species, the Cocos finch, found on Cocos Island in Costa Rica. These birds, though commonly referred to as finches, are actually part of the tanager family. Their closest known relative is the dull-colored grassquit from mainland South America, from which they are believed to have descended. The finches' evolution is a classic example of adaptive radiation. After the original grassquits arrived on the Galapagos Islands, they diversified into multiple species, each adapting to different ecological niches. This diversification is most famously observed in the variety of beak shapes among the species, which evolved to exploit different food sources such as seeds, insects, and cactus flowers. The finches are generally similar in size and color, but they can be distinguished by their diet, habitat, and particularly their beak size and shape. Some notable species include the critically endangered Mangrove Finch, known for its extremely limited range on Isabela Island, and the Woodpecker Finch, famous for its use of tools to extract insects from tree bark. Other species, like the Large Ground Finch, have evolved large, powerful beaks for cracking seeds, while the Vampire Finch, a subspecies of the Sharp-beaked Ground Finch, has developed a unique behavior of feeding on the blood of seabirds. Efforts to conserve these finches, especially those with small populations like the Mangrove Finch, involve captive rearing and habitat restoration to mitigate threats such as parasitism by introduced species and habitat loss. Conservationists are particularly focused on protecting these birds from the avian vampire fly (Philornis downsi), whose larvae can cause high mortality rates in finch nestlings. For more details on the conservation efforts and the unique characteristics of each finch species, you can explore resources from organizations like the Charles Darwin Foundation.