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their habits, nesting considerable distances apart^ and that they are not often visible 

 in the great woods and forests they frequent. II is difficult to understand how so 

 rapid a mobilisation of the species was effected over the vast area of their breeding 

 range, or to understand the impelling cause which drove them westward in numbers 

 sufficient to keep up a continuous stream, of many hours, past the island. 



The period of self-dependence is arrived at much sooner in certain birds than 

 in others. Some, like Tr'mga camthis, Sqvatarola helvetica, Calidris arenaria and Limosa 

 lapponica, nesting in very high latitudes, leave the East Coast of England in the 

 spring, often the last of snij, and their young are among the first to return in 

 autumn. The order of migration, more especially amongst the Limicolae, is the 

 occurrence early in the autumn, July and August, of a few old birds in more or 

 less faded summer plumage, either barren or such as have been prevented rearing their 

 young, then the young in large flights, and some weeks subsequently the old birds. 



It is worthy of remark that, in spring, T. camdus, S. helvetica, and L. lapponica, 

 in summer plumage, do not as a rule pass northward of the Spurn at the mouth 

 of the Hnmber, but leave the coast there. The line of migration followed by them, 

 is suggestive of an ancient coast line, which, towards the end. or perhaps subsequent 

 to the last glacial epoch, swept eastward or northeastward to Southern Scandinavia 

 and the mouth of the Baltic. 



With a dry summer in Northern Europe, migration is always earlier than in 

 years of great rain-fall and low temperature : birds nesting sooner in the former, 

 and the young arriving more quickly at maturity. 



Nothing, perhaps, is Diiore remarkable in the phenomena of migration than the 

 punctuality with which certain birds arrive in the autumn, the one species regu- 

 larly taking precedence of another, and coming nearly at the same date, year after 

 year. In the Limicolae and AnaHdae, the date of arrival often varies considerably, but 

 in species like Saxicola aenanthe, Btùticilla phaenicurus, Tiirdus pilaris, T. iliacus, Corvus 

 comix, Begidus cristatus and Scolopax riisticida, and others, we may almost predict to 

 a day the time of their appearance. 



Birds when on migration appear to follow with marvellous persistency, year 

 after year, the same lines, or great highways, of migration, when approaching or 

 leaving the shores of Great Britain. The constancy of these periodical xihenomena is 

 suggestive of some settled law governing the movement. In the autumn, especially, 

 there seems to be two distinct passages of birds going forward at the same time — 

 one which is connected with the normal flow in the spring, and ebb in the autumn, 

 across Europe of vast hosts of migrants, to and from their nesting quarters in 

 the coldest part of their range — north-east in the spring and southwest in autumn. 

 Quite independent of this, there is a continual stream or broad weve of birds coming 

 week by week and month after month on the eastern shores of Great Britain; 

 crossing Europe from east to west, or, not uncommonly, from points south of east, 

 to others north of west, and the reverse in sprig. These immigrants are chiefly those 

 common and wellknown visitants which make these islands their winter quarters, 

 taking the place of our summer residents. They come in one broad stream, but 

 denser on some particular lines or highways, and seem to cut the flylines of ordinary 

 migration at nearly right angles. One flank touches the Orkney and Shetland Islands, 

 the southern wing sweeps over the Channel Islands, shaping its course in a north- 

 westerly direction to the English Coast. 



Independent of the broad stream of immigrants which cross directly from the 

 east, there is in the autumn always a steady stream closely following the coast-line 

 from north to south, composed of birds either on the move from more northerly 

 districts in Great Britain, or of such as heva come in directly from the east and 



