USEFUL OR HARMFUL? 9 



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. 



The third international Ornithological Congress, held 

 in Paris in 1900, decided that the Governments of the 

 various European States should be called upon to have 

 the food of birds made the object of special investigations, 

 and to report the result, within a space of five years. 

 When the fourth International Congress met, however, 

 only Hungary and Belgium were able to report on the 

 subject. 



The publications of the Hungarian Ornithological 

 Centre are founded upon the collection of data, divided 

 into two main groups: i. The Migration data, so- 

 called historical, up to 1891, and again from that to the 

 present day. 2. Foreign data, partly taken from litera- 

 ture, and Special data relating to one species, from the 

 whole area of its habitation the Cuckoo for instance. 



The investigation of the economic role played by the 

 Rook (Corvus frugilegus L.), which English landowners 

 and farmers are beginning to feel is a matter of great 

 importance, was begun by the Central Bureau in 1893; 

 it is still going on. According to the results hitherto 



