ON BIRD MIGRATION. 369 



the north are recorded for November, carrying the extreme limit of the 

 period covered by this movement of the Skylark down to the 15th of that 

 month. Thus the autumnal immigration from the north, vast as it is, is 

 compressed, as it were, into the period of little more than four weeks. 

 The majority of these northern skylarks seem to disperse themselves over 

 our islands, some of them reaching the Hebrides, and replace the home- 

 bred birds which have already quitted their summer haunts. A great 

 many seek Ireland, either by direct passage from the south-west of Scot- 

 land or by way of the Isle of Man, while some may pass from the Welsh 

 coast to the shores of Dublin and Wicklow. 



4 and 5. Autumn Passage from Central and Northern Europe to 

 Southern Europe along the Britisli Coast. — These movements are much 

 involved with the immigratory movements from the north and east, and, 

 to a lesser degree, with the British emigratory movements already treated 

 of. The transient visitors whicli eftect it arrive on our northern islands 

 and along our north-eastern coast, together with those which winter with 

 us, in October, or in some years early in November, and after a short 

 rest proceed along the coast, chiefly by night, southward and westward, 

 crossing the Channel at various points. Though they are mainly confined 

 to our eastern and southern seaboards, yet a considerable number make 

 an overland journey across Great Britain, travelling down the west coast, 

 while others possibly cross to Ireland, and continue their southerly journey 

 along its eastern shores. The Passage movements from the east need no 

 further notice now, since they have been treated already under Section 2. 



General Remarks on. Autumn Emigration and Immigration. — Having 

 treated of the autumn movements, both of emigration and immigration, it 

 may be desirable before proceeding further to consider their effects on 

 the Skylark population of Britain, and its position at the end of that 

 season. Though a considerable number of home-bred birds have at that 

 time quitted our shores, their departure has not materially affected the 

 great abundance of the species, partly owing to the fact that the Skylark 

 is double-brooded,' and hence its annual increase is enormous, while 

 prodigious numbers have poured into England from Central Europe during 

 part of September and throughout October, to say nothing of the immense 

 number of immigrants from North-western Europe which have arrived 

 during the latter month. The result is that from November to the 

 setting in of cold weather the Skylark population of the British Isles is 

 at its maximum, and vastly in excess of what it is at any other period of 

 the year. 



G. Winter Emigration from, and Partial Migration ivithin, the British 

 Islands. — These movements depend wholly on the state of the weather, 

 and vary in degree according to its severity. The Skylark obtaining the 

 whole of its food on the ground is at once driven to change its quarters 

 "when that is covered with snow, and only somewhat less quickly when 

 it is merely frost-bound without snow. Should the late autumn and 

 winter be uniformly mild, the Skylarks sojourning with us remain practi- 

 cally stationary. Few, if any, winters are, however, entirely free from 

 snow or frost, and with the first outbreak of cold the birds must remove 

 themselves from its untoward influence. Sometimes suitable lodging may 

 be found not far off, and then the movement is but local or partial in 

 character. When this occurs, and the stress is but short, the birds soon 



' Tn many parts of England moat pairs of Skylarks have three nests in the year. 

 1901. BB 



