If the wind, by its contrary blasts, should begin to prevent the onward progress of the flight, the birds immediately take up small stones, or else fill their throats with sand, and so contrive to ballast themselves as they fly. The seeds of a certain venomous plant[175] are most highly esteemed by the quails as food; for which reason they have been banished from our tables; and a great repugnance is manifested to eating their flesh, on account of the epilepsy, to which alone of all animals, with the exception of man, the quail is subject. CHAPTER XII. SWALLOWS. The swallow, the only bird that is carnivorous among those which have not hooked talons, takes its departure also during the winter months; but it goes only to neighboring countries, seeking sunny retreats there on the mountain sides; sometimes they have been found in such spots bare and quite unfledged. This bird, it is said, will not enter a house in Thebes, because that city has been captured so frequently; nor will it approach the country of the Bizyæ, on account of the crimes committed there by Tereus. Cæcina, a member of the equestrian order, and the owner of several chariots, used to have swallows caught, and then carried them with him to Rome. Upon gaining a victory, he would send the news by them to his friends; for after staining them the color of the party that had gained the day, he would let them go, immediately upon which they would make their way to the nests they had previously occupied. Fabius Pictor also relates, in his Annals, that when a Roman garrison was being besieged by the Ligurians, a swallow which had been taken from its young ones was brought to him, in order that he might give them notice, by the number of knots on a string tied to its leg, on what day succor would arrive, and a sortie might be made with advantage. CHAPTER XIII. BIRDS WHICH TAKE THEIR DEPARTURE FROM US IN WINTER. In a similar manner also, the blackbird, the thrush, and the starling take their departure to neighboring countries; but they do not lose their feathers, nor conceal themselves, as they are often to be seen in places where they seek their food during the winter: hence it is that in winter, more especially, the thrush is so often to be seen in Germany. It is, however, a well-ascertained fact, that the turtle-dove conceals itself, and loses its feathers. The ring-dove, also, takes its departure, yet it is a matter of doubt whither they go. A peculiarity of the starling is to fly in troops, as it were, and then to wheel round in a globular mass like a ball, the central troop acting as a pivot for the rest. Swallows are the only birds that have a sinuous flight of remarkable velocity; so that they are not exposed to the attacks of other birds of prey: these are the only birds that take their food solely on the wing.