Mr. Waterton says there is a peculiarity in the nidification of the domestic swan too singular to be passed over without notice. At the time it lays its first egg the nest which it has prepared is of very moderate size; but as incubation proceeds we see it increase vastly in height and breadth. Every soft material, such as pieces of grass and fragments of sedges, is laid hold of by the sitting swan as they float within her reach, and are added to the nest. This work of accumulation is performed by her during the entire period of incubation, be the weather wet or dry, settled or unsettled; and it is perfectly astonishing to see with what assiduity she plies her work of aggrandisement to a nest already sufficient in strength and size to answer every end. My swans generally form their nest on an island quite above the reach of a flood; and still the sitting bird never appears satisfied with the quantity of materials which are provided for her nest. I once gave her two huge bundles of oaten straw, and she performed her work of apparent supererogation by applying the whole of it to her nest, already very large, and not exposed to destruction had the weather become ever so rainy. This same author continues:-- It is probable that this disposition to accumulation, in its general bearing, has reference to heat rather than the flood; but that the wild swan has a foresight regarding danger, and a quick perception as to the means of securing safety, appears from an instance mentioned by Captain Parry, in his Northern voyage. When everything was deeply involved in ice, the voyagers were obliged to pay much attention to discern whether they were travelling over water or land; but some birds, which formed their nest at no great distance from the ships, were under no mistake in so important a matter; and when the thaw took place it was seen that the nest was situated on an island in the lake. The following cases are likewise taken from Couch (_loc. cit._, p. 225):--