There are four birds that have names that start with the letter X: Xantus's Hummingbird, Xantus's Murrelet, Xavier's Greenbul and Xinjiang Ground-Jay. Among the approximately 10,000 species of birds around the world, these are the only four with names that begin with "X."
- Xantu's Hummingbird is found in Baja California and boasts an orange chest with purple-brown wings.
- Xantus's Murrelet is one of the world's rarest seabirds. It can be found in the coastal Pacific waters.
- Xavier's Greenbul is found in several African nations and is a songbird. The bird gets its name from an explorer that researched specimens in Congo.
- The Xinjiang Ground-Jay, which is also known as the Biddulph's Ground Jay, is found in China. It is about the size of a human's hand.