The terms refer especially to Cliff Swallows, who build their nests from mud and dirt. Other swallow species nest in tree holes or dirt banks, but the name is used for all types of swallows. The second name was provided by Mark Soldierwolf. He said they are called ‘ghosts’ because of the strange sound they make at night after they enter their nests. This word corresponds in part to the Gros Ventre word for cliff swallow, which is biitei-wosish or biitei-bii3os’i.
A swarm of cliff swallows near a bridge under which they were nesting.