Crows are the most intelligent of birds. Like the other fowls of the air in which the brain is well developed, they build rough untidy nests--mere platforms placed in the fork of a branch of almost any kind of tree. The usual materials used in nest-construction are twigs, but crows do not limit themselves to these. They seem to take a positive pride in pressing into service materials of an uncommon nature. Cases are on record of nests composed entirely of spectacle-frames, wires used for the fixing of the corks of soda-water bottles, or pieces of tin discarded by tinsmiths. Four, five or six eggs are laid; these are of a pale greenish-blue hue, speckled or flaked with sepia markings. The hen alone collects the materials for the nest, but the cock supervises her closely, following her about and criticising her proceedings as she picks up twigs and works them into the nest. From the time of the laying of the first egg until the moment of the departure of the last young bird, one or other of the parents always mounts guard over the nest, except when they are chasing a koel. Crows are confirmed egg-lifters and chicken-stealers; they apply their standard of morality to other birds, and, in consequence, never leave their own offspring unguarded. A crow's nest at which there is no adult crow certainly contains neither eggs nor young birds. As has already been stated, crows spend, much time in teasing and annoying other birds. Retribution overtakes them in the nesting season. The Indian koel (_Eudynamis honorata_) cuckolds them. The crows either are aware of this or have an instinctive dislike to this cuckoo. The sight of the koel affects a crow in much the same way as a red cloth irritates a bull. One of these cuckoos has but to perch in a tree that contains a crow's nest and begin calling in order to make both the owners of the nest attack him. The koel takes full advantage of this fact. The cock approaches the nest and begins uttering his fluty _kuil_, _kuil_. The crows forthwith dash savagely at him. He flies off pursued by them. He can easily outdistance his pursuers, but is content to keep a lead of a few feet, crying _pip-pip_ or _kuil-kuil_, and thus he lures the parent crows to some distance. No sooner are their backs turned than the hen koel slips quietly into the nest and deposits an egg in it. If she have time she carries off or throws out one or more of the legitimate eggs. When the crows return to the nest, having failed to catch the cock koel, they do not appear to notice the trick played upon them, although the koel's egg is smaller than theirs and of an olive-green colour. Through the greater part of June and July the koels keep the crows busy chasing them. Something approaching pandemonium reigns in the neighbourhood of a colony of nesting crows: from dawn till nightfall the shrieks and yells of the koels mingle with the harsh notes of the crows.