20 DISPERSAL AND MIGRATION. [part i. 



of April, however cold it may be, while its departure may take 

 place from the end of September to late in October, and is said by 

 Forster to occur on the first N. or KE. wind after the 20th of 

 September. 



Almost all the migratory birds of Europe go southward to 

 the Mediterranean, move along its coasts east or west, and cross 

 over in three places only ; either from the south of Spain, in the 

 neighbourhood of Gibraltar, from Sicily over Malta, or to the 

 east by Greece and Cyprus. They are thus always in sight of 

 land. The passage of most small birds (and many of the larger 

 ones too) takes place at night ; and they only cross the Mediter- 

 ranean when the wind is steady from near the east or west, 

 and when there is moonlight. 



It is a curious fact, but one that seems to be well authenti- 

 cated, that the males often leave before the females, and both 

 before the young birds, which in considerable numbers migrate 

 later and alone. These latter, however, seldom go so far as the 

 old ones ; and numbers of young birds do not cross the Mediter- 

 ranean, but stay in the south of Europe. The same rule applies 

 to the northward migration; the young birds stopping short 

 of the extreme arctic regions, to which the old birds migrate. 1 

 When old and young go together, however, the old birds take 

 the lead. In the south of Europe few of the migratory birds 

 stay to breed, but pass on to more temperate zones ; thus, in the 

 south of France, out of 350 species only 60 breed there. The 

 same species is often sedentary in one part of Europe and migra- 

 tory in another ; thus, the chaffinch is a constant resident in 

 England, Germany, and the middle of France ; but a migrant in 

 the south of France and in Holland : the rook visits the south 

 of France in winter only : the Falco tinnunculus is both a 

 resident and a migrant in the south ot France, according to 

 M. Marcel de Serres, there being two regular passages every 

 year, while a certain number always remain. 



1 Marcel de Serres states this as a general fact for wading and swimming 

 birds. He says that the old birds arrive in the extreme north almost alone, 

 the young remaining on the shores of the Baltic, or on the lakes of Austria, 

 Hungary, and Russia. See his prize 'essay, Des Causes des Migrations, &c. 

 2nd ed., Paris, 1845, p. 121. 



