Here, as they fly before a southern wind, they are on their way to the north in the spring. But in another passage he seems rather to be thinking of autumn; it is where he is telling the husbandman how to presage an approaching storm, such a storm as descends in autumn from the Alps upon the plains of Lombardy:—
Nunquam imprudentibus imber Obfuit; aut illum surgentem _vallibus imis_ Aeriae fugere grues, aut bucula coelum Suspiciens patulis captavit naribus auras, Aut arguta lacus circumvolitavit hirundo.[61]
The general tenor of the whole passage of which these lines are a fragment, as well as their original in the _Diosemeia_ of Aratus, points to the approach of ‘hiems,’ the stormy season, as the event indicated; the falling leaves dance in air, the feathers of the moulting birds float on the water, but the swallow is not yet gone. The deep Alpine valleys seethe with swirling mist, which rises into gathering cloud, and soon becomes stormy rain beating upon the plains, as we may see it in any ‘Loamshire’ of our own, that lies below the stony hills of a wilder and wetter country-side. In this striking and truthful passage, Virgil has not followed his model too closely, but was evidently thinking of what he must often have witnessed himself.
The Stork is only mentioned by Virgil in a single passage—
Cum vere rubenti Candida venit avis longis invisa colubris.[62]
Doubtless the bird arrived in great numbers in spring on the Mantuan marshes, and found abundance of food there in the way of frogs and snakes. Its snake-eating propensity was considered so valuable in Thessaly, that the bird was preserved there by law, says Aristotle.[63] But did it remain to breed in Italy? It is remarkable that both Aristotle and Pliny have very little to say of its habits, and hardly anything as to its breeding; and if the Stork had been a bird familiar to them, they could hardly have failed to give it a prominent place in their books. At the present time it seems to pass over Italy and Greece on its passage northwards, never staying to breed in the former country and rarely in the latter; yet this can hardly be owing to temperature, as it breeds freely in the parallel latitudes of Spain and Asia Minor.