Some birds became so greatly interested in the camp that they wanted to nest there. One bird (we believe it was always the same one) could not be kept away and used to come every day, until at last he was carried away by Brocklehurst, a wildly struggling, unconquerable being. The old birds enjoy play, while the young ones are solely engaged in satisfying the enormous appetites they have when growing. While the _Nimrod_ was frozen in the pack some dozens of them disported themselves in a sea-pool alongside. They swam together in the duck fashion, then at a squawk from one they all dived and came up at the other side of the pool. Early in October they began to arrive at the rookery, singly or in pairs. The first to come were the males, and they at once began to scrape up the frozen ground to make hollows for nests, and to collect stones for the walls with which they surrounded them. [Illustration: An Adelie calling for a Mate after commencing the Nest. (_See page 242_)] When the rookery is pretty well filled, and the nest-building is in full swing, the birds have a busy and anxious time. To get enough suitable small stones is a matter of difficulty, and may involve long journeys for each single stone, so the temptation is too strong for some of the birds, and they become habitual thieves. The bearing of the thief, however, clearly shows that he knows that he is doing wrong, for very different is his furtive look, even after he is quite out of danger of pursuit, from the expression of the honest penguin coming home with a hard-earned stone. A thief, sitting on its own nest, was stealing from an adjacent nest, whose honest owner was also at home but looking unsuspectingly in another direction. Casually the latter turned his head and caught the thief in the very act, whereupon the culprit dropped the stone and pretended to be busy picking up an infinitesimal crumb from the neutral ground. Undoubtedly then the penguin has a conscience, at least a human conscience, that is the fear of being found out. This stone-gathering is a very strong part of the nesting instinct, and even if at a late stage the birds lost their eggs or their young, they began again, in a half-hearted way, to heap up stones. Unmated birds occupied the fringe of the rookery, and amused themselves piling and stealing till the chicks began to hatch out. After the two eggs were laid the males--who always seemed to be in the majority--used to do most of the work, and judging from certain signs it would seem that some of the birds never left their nests to feed during the whole period of incubation. Many birds lost their mates through the occasional breaking loose of a dog, and these birds could not leave their nests. CHAPTER XLVI THE ADELIES AND THEIR CHICKS