Gulls are all robbers by instinct but have not the power and courage of the predaceous Bonxie or Great Skua of the Shetlands, a pirate by profession who lives mainly on the labours of others. The gull must fend for himself and levy tribute when he gets the chance, when he can intimidate some other bird or snatch a morsel from his beak. From the gannet he gets nothing; it would be dangerous for him to come in that bird's way, and no sooner is the fish caught than it is swallowed. The gannet takes no more notice of the gull than of a bubble floating on the surface, and probably does not even know that the negligible bird regards his fishing operations with a good deal of interest and hungrily wishes he could have a share in the spoil. But how far gulls will go in their desire to get something for nothing may be seen in the following incident which was witnessed by some fishermen at Sennen Cove, close to the Land's End. A Great Northern Diver made its appearance at the cove and spent a part of the winter there, and as he was not disturbed and grew accustomed to the sight of human beings he lost all shyness and often fished close to the rocks where the men stood watching him. One day they saw him with a small flat fish which he could not swallow; it was too broad to go down his gullet, but he would not let it escape and continued to toss it up and catch it again, as if determined to get it down somehow. Or it may have been that he was only playing with it just as a cat when not hungry plays with a mouse. By and by a black-backed gull swam to him and began following him and making snatches at the flounder each time the diver tossed it up. But the diver would not let him have the fish, he simply turned round to get away from the teasing gull, and the quiet way in which he took it only emboldened the other until he became quite excited and was almost violent in his efforts to get the fish. Then suddenly the diver, dropping the fish, turned on him and struck him like lightning, driving his sharp powerful beak into his neck or the base of the skull. The gull flapped his wings violently once or twice, then turned over and floated away, belly up, quite dead. Instantly after dealing the blow, the diver went down and quickly reappeared with the flounder, and resumed tossing and catching it again, just as if nothing had happened, while the dead gull slowly drifted further and further away.