In very dry summer weather, Rooks are put to great shifts in obtaining food. Grubs and worms descend to a great depth to get beyond the influence of the drought, and the soil is too parched and hard for digging; they then retire to the sea-shore, to marshes, fresh-water and salt, to cabbage and potato gardens, and in the last-named localities they are again disposed to become marauders. To fruit gardens they are rarely permitted to resort, or they would commit great ravages. As the season advances, ripe walnuts are a very powerful attraction, and when they have discovered a tree well supplied with fruit, a race ensues between them and the proprietor as to which shall appropriate the greater share, so slyly do they watch for opportunities, and so quick are they in gathering them and carrying them off in their beaks. In long winter frosts, or when the ground is covered with snow, they are again reduced to straits. Some resort to the sea-shore and feed on garbage of all kinds, some to turnip-fields where they dig holes in the bulbs. They have also been observed to chase and kill small birds, which, as near starvation as themselves, have been unable to fly beyond their reach, and I have even seen a Rook catch a small fish.
I must not conclude this imperfect sketch without noticing a peculiar habit of Rooks, which is said to portend rain. A flock will suddenly rise into the air almost perpendicularly, with great cawing and curious antics, until they have reached a great elevation, and then, having attained their object, whatever that may be, drop with their wings almost folded till within a short distance of the ground, when they recover their propriety, and alight either on trees or on the ground with their customary grave demeanour. Occasionally in autumn, as White of Selborne remarks,
Sooth'd by the genial warmth, the cawing Rook Anticipates the spring, selects her mate, Haunts her tall nests, and with sedulous care Repairs her wicker eyrie, tempest torn.
Similar instances of this unseasonable pairing are recorded by modern ornithologists.
Efforts are sometimes made, and not always unsuccessfully, to induce Rooks to establish a colony in a new locality. One plan is to place some eggs taken from a Rook's nest in that of some large bird which has happened to build in the desired spot, that of a Crow for instance, a Magpie, Jackdaw, Jay, or perhaps a Mistle Thrush. If the young are reared, it is probable that they will return to breed in the same place in the following year. Another plan which has been tried with success is to place several bundles of sticks, arranged in the form of nests, among the highest branches of the trees which it is desired to colonize. Stray Rooks in quest of a settlement, mistaking these for ruins of old nests, accept the invitation and establish themselves if the locality suits them in other respects.