among the rook's most determined enemies, and cases of rookeries being destroyed by both birds are on record. On the other hand, though the heron is the far more powerful bird of the two, heronries have likewise been scattered, and their trees appropriated, by rooks, probably in overwhelming numbers. Of the two the heron is, particularly in the vicinity of a preserved trout stream, the more costly neighbour. Indeed it is the only other bird which nests in colonies of such extent, but there is this marked difference between herons and rooks, that the former are sociable only in the colony. When away on its own business, the heron is among the most solitary of birds, having no doubt, like many other fishermen, learnt the advantage of its own company. One of the most remarkable habits in the rook is that of visiting the old nests in mid-winter. Now and again, it is true, a case of actually nesting at that season has been noticed, but the fancy for sporting round the deserted nests is something quite different from this. I have watched the birds at the nests on short winter days year after year, but never yet saw any confirmation of the widely accepted view that their object is the putting in order of their battered homes for the next season. It seems a likely reason, but in that case the birds would surely be seen carrying twigs for the purpose, and I never saw them do so before January. What other attraction the empty nurseries can have for them is a mystery, unless indeed they are sentimental enough to like revisiting old scenes and cawing over old memories. The proximity of a rookery does not affect all people alike. Some who, ordinarily dwelling in cities, suffer from lack of bird neighbours, would regard the deliberate destruction of a rookery as an act of vandalism. A few, as a matter of fact, actually set about establishing such a colony where none previously existed, an ambition that may generally be accomplished without extreme difficulty. All that is needed is to transplant a nest or two of young rooks and lodge them in suitable trees. The parent birds usually follow, rear the broods, and forthwith found a settlement for future generations to return to. Even artificial nests, with suitable supplies of food, have succeeded, and it seems that the rook is nowhere a very difficult neighbour to attract and establish.