The cold sharpened. To the estuary came sanderlings in white winter dress, who ran at the tide-line like blown sea-foam. Snow buntings followed, and went south with them. The flatfish swam to warmer water beyond the bar, and often when the otters dived in the estuary they rose empty-mouthed to the surface, except perhaps for a green crab. Old Nog the heron grew so thin that he looked like a bundle of grey flags stripped by wind and clinging to two reeds. His inland fishing ponds were frozen, most of the streams ran under plates of ice, and the only food he could spear was to be found at low tide in the pools of the Shrarshook Ridge, where gravel had been dug. The pans and plains of the Burrows were crossed by a thousand tracks, the prints of larks, finches, wagtails, crows, and gulls; the presses of weasels, rabbits, and stoats; the pads of badgers and foxes; the triple toes of herons and bitterns, like the veining of leaves. Many of the smaller birds were so weak they could not fly, and their bodies were eaten by rats and weasels, which were eaten by the larger owls and hawks. Other otters from the Two Rivers came down to the estuary, some of them cubs of ten or twelve pounds in weight, who had kept together with their mothers. Families of three and four and one of five--a bitch and four cubs from the boggy moorland hill where the Two Rivers began in the peat--came to the duckpond along the otter path from the saltings, and finding it frozen, went down the pill and out to the coast. Tarka met White-tip with her mate by an overturned hulk one night; she was scratching at the webmark of a widgeon, frozen in the mud with its scent. One look, and they had passed in the darkness.