The reverberations, too, of the mountains, and the roaring of the forests, are indicative of certain phænomena; and the same is the case when the leaves are seen to quiver,[705] without a breath of wind, the downy filaments of the poplar or thorn to float in the air, and feathers to skim along the surface of the water.[706] In champaign countries, the storm gives notice of its approach by that peculiar muttering[707] which precedes it; while the murmuring that is heard in the heavens affords us no doubtful presage of what is to come. CHAP. 87.—PROGNOSTICS DERIVED FROM AQUATIC ANIMALS, AND BIRDS. The animals, too, afford us certain presages; dolphins, for instance, sporting in a calm sea, announce wind in the quarter from which they make their appearance.[708] When they throw up the water in a billowy sea, they announce the approach of a calm. The loligo,[709] springing out of the water, shell-fish adhering to various objects, sea-urchins fastening by their stickles upon the sand, or else burrowing in it, are so many indications of stormy weather: the same, too, when frogs[710] croak more than usual, or coots[711] make a chattering in the morning. Divers, too, and ducks, when they clean their feathers with the bill, announce high winds; which is the case also when the aquatic birds unite in flocks, cranes make for the interior, and divers[712] and sea-mews forsake the sea or the creeks. Cranes when they fly aloft in silence announce fine weather, and so does the owlet,[713] when it screeches during a shower; but if it is heard in fine weather, it presages a storm. Ravens, too, when they croak with a sort of gurgling noise and shake their feathers, give warning of the approach of wind, if their note is continuous: but if, on the other hand, it is smothered, and only heard at broken intervals, we may expect rain, accompanied with high winds. Jackdaws, when they return late from feeding, give notice of stormy weather, and the same with the white birds,[714] when they unite in flocks, and the land birds, when they descend with cries to the water and besprinkle themselves, the crow more particularly. The swallow,[715] too, when it skims along the surface of the water so near as to ripple it every now and then with its wings, and the birds that dwell in the trees, when they hide themselves in their nests, afford similar indications; geese, too, when they set up a continuous gabbling,[716] at an unusual time, and the heron,[717] when it stands moping in the middle of the sands. CHAP. 88.—PROGNOSTICS DERIVED FROM QUADRUPEDS.