The glutis is found in some medieval encyclopedias. It is said to have a very long tongue. When winter is near it eagerly starts its migration journey, following the swallows and storks, but it soon tires and falls behind, traveling so slowly winter arrives before it completes the journey.

Pliny the Elder says this bird gets its name glutis from a Greek word, probably glôtta (tongue), from which Pliny's use of the Latin word glottis (throat) became glutis in Thomas of Cantimpré's encyclopedia.