The Sloane MSS Series: Sloane MS 20 BAT

Kongelige Bibliotek, Gl. kgl. S. 1633 4º, Folio 42v 

Latin name: Vespertilio
Other names: Chauve-souris
A bird that gives birth to living young

General Attributes

A bat is not a noble bird. It is unlike other birds in that it gives birth to live young instead of laying eggs, and it has teeth. Bats gather together and hang from high places like a bunch of grapes; if one falls, all the rest also fall.

Sources (chronological order)

Pliny the Elder [1st century CE] (Natural History, Book 10, 81): The bat is the only flying creature that bears live young and feeds them with its milk; it also carries its children in its arms as it flies.

Isidore of Seville [7th century CE] (Etymologies, Book 12, 7:36): The bat, unlike other birds, is a flying quadruped, resembling a mouse. It has its name (vespertilio) from the time when it flies, after twilight. It flies about driven by precipitate motion, hangs from frgile branchs, and makes a sound like a squeak.