Rooks are easily approached in the autumn, when gorging the acorns. They may often be seen flying carrying an acorn in the bill. Sometimes a flock will set to work and tear up the grass by the roots over a wide space--perhaps nearly half an acre--in search of a favourite beetle. The grass is pulled up in little wisps, just about as much as they can hold in their beaks at a time. In spring they make tracks through the mowing grass--not in all the meadows, but only in one here and there, where they find the food they prefer. These tracks are very numerous, and do the grass some damage. Besides following the furrows made by the plough, and destroying grubs, beetles, wireworm, and other pests in incalculable numbers, they seem to find a quantity of insect food in unripe corn; for they often frequent wheatfields only just turning yellow, and where the grain is not yet developed. Except perhaps where they are very numerous, they do much more good than harm. Rooks may now and then be seen in the autumn, on the hayricks; they pull the thatch out, and will do in this way an injury to the roof. Therefore old black bottles are often placed on the thatch in order to scare them. It is said that they pull out the straw for the stray grains left in the ear by the threshing machine. This seems doubtful. It appears more probable that some insect found on the straw attracts them. If you are walking past a feeding flock, the nearest rook to you will often exhibit a ridiculous indecision as to whether he shall fly or not. He stretches his neck and leans forward as if about to spring, stops, utters a questioning `Cawk?' then watches you a moment and gives a hop, just opens his wings, shuts them, and descends within a couple of feet. `Cawk!' again. Finally, if you turn from your course and make a step towards him, he rises, flaps his wings three or four times, extends them, and glides a dozen yards to alight once more. Sometimes a flock will rise in the air, and silently wheel round and round after each other, gradually ascending and drifting slowly with the current till they reach a great height. When they soar like this it is said to foretell fine weather. At another time a flock will go up and wheel about in the strangest irregular manner. Every now and then one will extend his wings, holding them rigid, and dive downwards, in his headlong descent wavering to and fro like a sheet of paper falling edge first. He falls at a great pace, and looks as if he must be dashed to pieces against a tree or the earth; but he rights himself at the last moment, and glides away and up again with ease. Occasionally two or three rooks may be seen doing this at once, while the rest whirl about as if possessed; and those that are diving utter a gurgling sound like the usual cawk prolonged--`caw-wouk.' These antics are believed to foretell rough winds.