During incubation the male assiduously feeds his sitting mate, and occasionally changes places with her; and after the young are out of the shells both parents are engaged incessantly in collecting food for them. From early morning until dark they may be seen flying to and from the rookery, on each return journey carrying a cluster of worms and grubs in the mouth. When the young are fully fledged they are seen perching awkwardly on the branches near the nest, occasionally making short, tentative flights, and apparently anxious to go forth into that wide green world spread out beneath their cradle and watch-tower. They are, happily, ignorant of the doom that awaits them; for the time is now near when the blood-tax must be levied on the community--the price which is paid for protection; and, the young only being eatable, the slaughter must fall on them. As a rule, a few of the young escape death, as, when the shooting begins, and the old birds rise in haste to scatter in all directions, a few of the most advanced young birds that are already strong on the wing follow their parents to a place of safety. After the breeding season, which is usually over at the beginning of June, the rookery is forsaken; in some cases the birds disappear, and do not return until the next spring; more often they pay an occasional visit to the rookery, and some rookeries are visited almost daily by the birds. But for the rest of the year their roosting-place is elsewhere, often at a considerable distance. In districts where rooks are abundant there is generally one great roosting-place, where the communities inhabiting the country for many miles around are accustomed to congregate at the end of each day. As the evening draws near the birds begin to arrive from two, or three, or more directions, in detachments or long, loose trains, flying steadily, at an equal height above the ground. Where they settle the tree-tops are black with their numbers; and as fresh contingents pour in the noise of the cawing grows louder and more continuous, until it is in volume like the sound of a surging sea. At intervals large numbers of birds rise up, to hang like a black cloud above the trees for some minutes, but as the evening darkens they all finally settle down for the night; still, in so vast an assemblage there are always many waking individuals, and a noise of subdued cawing may be heard throughout the hours of darkness. With the returning light there is a renewal of the loud noise and excitement, as the birds rise up and wheel about in the air before setting out on their journey to their distant feeding-grounds. Raven. Corvus corax. [Illustration: FIG. 57.--RAVEN. ¹⁄₁₂ natural size.] Black with purple reflections; tail black; iris with two circles, the inner grey, the outer ash-brown. Length, twenty-five inches. * * * * *