In the meantime Baron Hans von Berlepsch of Seebach developed his system for the protection and propagation of the most useful birds, the main points of which were the feeding and providing with nesting opportunities of such birds. Thereby bird protection was diverted into a rational direction, which met with hearty sympathy on the part of M. de Darányi; consequently the Hungarian Central Office for Ornithology included this branch of ornithology in the work it set itself to do. The course followed by rational bird-protection in Hungary is as follows. It starts with the idea that nature itself knows neither useful nor noxious birds, but only necessary ones, which have developed according to the laws of nature, and on the basis of their development are performing in the world of nature the work which is appropriate to their organism. The manifold character of the work performed by birds is in harmony with the variety of these organisms. The question of the usefulness and noxiousness of birds during the whole of the nineteenth century was treated only approximately, upon the assertions of authorities. When, later on, Congresses began to embrace the cause of bird-protection, and the question of the usefulness or noxiousness of each species assumed a rôle of the first importance, it turned out that there was no firm basis upon which to rely, in passing judgment. Eminent ornithologists were often at variance with regard to the usefulness or noxiousness of a particular species. Where Nature is intact, the number of birds is automatically regulated in accordance with the natural development of their surroundings. The conceptions of “useful” and “noxious” are merely human ones; and man can, by cultivation or the contrary, alter the normal conditions; and may, consequently, modify the character and habits of birds also. Agriculture on a large scale, modern forestry, the draining of territory--all these things alter the fundamental conditions of animal life, and in consequence of bird-life also; and if these modifications in respect of birds are injurious to man, it is in the interests of man to adapt them artificially for the benefit of birds; and if by cultivation man deprives useful birds of their natural nesting facilities, he ought to provide them with artificial ones. This is the principle on which Baron von Berlepsch founded his system, which was accepted and applied in Hungary, together with the modifications required by special circumstances, or such as were introduced as the result of experience. These principles apply chiefly to those species which remain with us during summer and winter alike, and which are useful to agriculture. But the international protection of birds is important as regards those useful species that are migratory, and, as they migrate, pass through countries where--as is the case in Italy--the birds are caught _en masse_, and where bird-catching is carried on as a trade.