150 THE GOLDEN ORIOLE 



of the Corsican and Sardinian force. In this way the whole of 

 Middle Europe, the country south of the North and Baltic Seas, is 

 gradually colonised by converging waves of immigrants by one or 

 other of these routes. In the east of Europe the northern limit of 

 the species extends to somewhat higher latitudes than in the west, 

 and it is not uncommon in some parts of Finland. 



Apparently, in many cases, the same individual birds return 

 annually to their breeding haunts, and in about the same numbers. 

 This is one of those statements which it is almost impossible to prove, 

 but the weight of the evidence is so strong that there is no reasonable 

 doubt. In the first place, there are several instances on record in 

 which a brood has been successfully hatched off', and in the following 

 year the birds have built their nests again in the identical fork of the 

 bough which was occupied in the previous year. This has been known 

 to occur for several years in succession when the birds have not been 

 disturbed. Then again, there is a certain individuality about the 

 whistle of each bird, and just as it is possible to recognise the song of 

 a certain thrush by some peculiarity of intonation, so it sometimes 

 happens that the note of some particular oriole may be recognised in 

 the same district year after year. Another factor which enables the 

 intrusion of a young cock into a district formerly occupied by an old 

 male to be readily noted, is that the full plumage of black and gold is 

 not acquired in the second year, but the young male breeds for the 

 first time in a plumage which closely resembles that of the hen. 



In spite of the fact that the males lead the way across the Medi- 

 terranean, it is most probable that the oriole is a life-paired bird, and 

 that the cock is rejoined by his mate at the breeding-place, or, in 

 some cases, even beforehand, for most of the birds which visit us 

 appear to be already paired. 



Each male has his own little district, and now the rich, fluty 

 whistle resounds from the tree-tops in all directions. Where the bird 

 is common, as, for example, in the tall oaks of the old country gardens 

 of Dutch Brabant, or the oak woods surrounding the chateaux of 



