The swallow is noisy, flies in circles, takes its food from the air, and is skilled in nest building and in raising its young. Knowing that a building is about to collapse, the swallow leaves before that happens. In winter, the swallow goes across the sea and returns in the spring. If the eyes of young swallows are injured, the mother has the medical skill to make them see again.

One of the names used for the swallow, irundo, is also used for the sea-swallow. The distinction is clear from context.

As the swallow does not feed on the ground but remains in the air and eats only what it can catch there, so those who have no use for earthly things seek the things of heaven.

A cure for many ills of the human body, including a deadly throat disease, can be made from the ashes of burned swallow chicks. A drink made from their ashes aids in the reconciliation of spouses.The bellies of swallow chicks contain white or red pebbles, which are said to be used for magic. (Thomas of Cantimpré says that most swallows carry jewels in their livers. This gem is sometimes red, sometimes black, and is called celandine: it is useful for lunatics and drives away harmful fluids; when washed with water, it heals weak eyes.)