1. Land animals have also the same disposition for concealment. For in winter they all hasten to conceal themselves, and appear again when the season becomes warmer. Animals conceal themselves to guard against the excesses of temperature. In some the whole race is concealed; in others only a part of them. All the testacea conceal themselves, as those which are marine, the purpura, whelk, and all that class; but the state of concealment is more conspicuous in those which do not adhere to rocks; for these also conceal themselves, as the pectens. Some have an operculum on their exterior, as the land snails; and the alteration of those that are not free is inconspicuous. They do not all conceal themselves at the same period; for the snails are torpid during the winter, the purpura and whelk for thirty days under the dog star, and the pectens at the same period. Most of them conceal themselves in very cold and very hot weather.
2. Almost all insects become torpid, except those which dwell in the habitations of men, and those that perish and do not survive for a year. They are torpid in the winter. Some conceal themselves for a good while, others only in the coldest days, as the bees, for these also conceal themselves. This is shown by their not touching the food which is prepared for them; and if any of them creep out, they appear transparent, and plainly have nothing in their stomach. They remain at rest from the setting of the Pleiades until the spring. Animals pass their torpid state in warm places, and in the spots they are accustomed to inhabit.
Chapter XVII.
1. Many sanguineous animals become torpid, as those which are furnished with scales, the serpent, lizard, gecko, and the river crocodile, during the four winter months in which they eat nothing. Other serpents conceal themselves in the earth, but the viper lies hidden among stones. Many fish also become torpid, especially the hippurus and coracinus during the winter; for these alone are never taken but at certain seasons, which never vary. Almost all the rest are taken at all seasons. The lamprey, orphus, and conger conceal themselves. The rock fish conceal themselves in pairs, as the cichla, cottyphus, and perca, the male with the female, in which way also they prepare for their young.
2. The tunny conceals itself during winter in deep places, and they become fattest at this season. The season of capturing them commences with the rising of Pleiades, and continues to the end of the setting of Arcturus. All the rest of their time they remain quiet in concealment. A few of these are taken during the period of their concealment, and so are some other hybernating creatures, if they are disturbed by the warmth of their abode or the unusual mildness of the season. For they come out a little from their holes to feed, and also when the moon is full. Most fish are better tasted during the period of concealment. The primades bury themselves in the mud. This is shown by their not being taken, or their seeming to have a great deal of mud on their backs and their fins pressed down.
3. In spring, however, they begin to move and come to the shore to copulate and deposit their ova. At this season they are captured full of ova, and then also they appear to be in season, but are not so good in autumn and winter. At the same season also the males appear to be full of melt. When their ova are small they are taken with difficulty; but as they grow larger many are taken when they are infested by the œstrus. Some fish bury themselves in sand, others in mud, with only their mouths above the surface. Fishes usually conceal themselves only in the winter. The malacostraca, the rock fishes, the batus, and selache only in the most severe weather. This is shown by the difficulty of capturing them in cold weather.
4. Some fish, as the glaucus, conceal themselves in summer time; for this fish hides itself for sixty days in the summer time. The onus and the chrysophrys hide themselves. The reason for supposing that the onus hides itself for a long while appears to be that it is captured at long intervals; and the influence of the stars upon them; and especially of the dog-star, appears to be the cause of their hiding themselves in summer time, for the sea is then disturbed. This is most conspicuous in the Bosphorus; for the mud is thrown up, and the fish are thus brought to the surface; and they say that, when the bottom is disturbed, more fish are often taken in the same cast the second than the first time; and after much rain animals make their appearance which before were either not seen at all or but seldom.
Chapter XVIII.
1. Many kinds of birds also conceal themselves, and they do not all, as some suppose, migrate to warmer climates; but those which are near the places of which they are permanent inhabitants, as the kite and swallow, migrate thither; but those that are farther off from such places do not migrate, but conceal themselves; and many swallows have been seen in hollow places almost stripped of feathers; and kites, when they first showed themselves, have come from similar situations. Birds with crooked claws, and those also with straight claws, conceal themselves indiscriminately; for the stork, blackbird,[217] turtle dove, and lark hide themselves, and by general agreement the turtle dove most of all, for no one is ever said to have seen one during the winter. At the commencement of hybernation it is very fat, and during that season it loses its feathers, though they remain thick for a long while. Some of the doves conceal themselves; others do not, but migrate along with the swallows. The thrush and the starling also conceal themselves, and among birds with crooked claws the kite and the owl are not seen for a few days.