J. E. LITTLEBOY — THE MIGRATION OF BIRDS. 33 



tlip power of " Home Instinct " — under this distinctive title. 

 They are each, as it seems to me, but part and parcel of a whole — 

 absolutely inseparable the one from the other — and when con- 

 sidered as such, I believe that they will be found to shed a very 

 important light on the difficult questions under discussion. 



It appears to be impossible, with the limited amount of know- 

 ledge at present in our possession, to lay down a hard and 

 fast line in reference to this subject. Contradictions, which it 

 seems difficult to account for, are met with at almost every turn. 

 I will enumerate just a few of them. Streams of birds of the same 

 species are occasionally found crossing the Channel in opposite 

 directions on the same day. To quote the Avords of the report 

 before referred to : * — " In the autumn, there is what may be called 

 a double stream of birds, crossing each other near the entrance to 

 the English Channel, that is, from the Essex and Kent coast 

 towards the S.E on the French and Belgium coast, and again, in 

 an opposite direction, from Belgium to the coast of Kent." The 

 same report states that " during the very severe weather in the 

 early part of 1881, as well as in December, flocks of birds came 

 to lis direct from the French coast, or from south to north ; " a 

 course directly the reverse of what might have been anticipated. 

 In a letter dated Ulceby, Lincolnshire, September 19th, 1881, Mr. 

 Cordeaux writes as follows : "I have frequently, in the late autumn, 

 observed at this place, large migrations of geese, plovers, and larks, to 

 the north and north-west, and I generally find that it is a sign of mild 

 open weather for some time to come." Here, again, is a fact 

 which seems to contradict all preconceived anticipations. There 

 is, also, good reason to believe that stonechats and a few other birds 

 migrate f over central Europe, fi-om east to west and from west to 

 east, crossing the line of ordinary migration at right angles. 



It must be admitted that these diversions of route, although 

 governed, in all probability, by the same laws that regulate ordinary 

 migration, appear to be more or less at variance with accepted 

 theories. Herr Gatke, the veteran observer at Heligoland, a gentle- 

 man who has studied the subject with great zeal and intelligence, 

 at what is probably the most favourable station in the world, thus 

 writes respecting migration to his friend, Mr. J. Cordeaux : — " The 

 'how' we may in time determine, but the 'why' not before you 

 and I migrate to the unknown world, or learn the language of 

 birds and are told it in their own tongue." On looking at the 

 subject as a whole, we must, I think, be content to assume that 

 the many diversities and eccentricities of migration are the result 

 of ever-varying local causes, such as inequality of temperature, 

 storms, and the premature abundance or scarcity of food, but 

 I think that these apparent contradictions should not prevent an 

 attempt being made to generalise the conclusions to which known 

 and admitted facts evidently tend. 



• ' Rep. Brit. Assoc, for 1881.' p. 191. 



t 'Transactions of the Norfolk and Norwich Naturalists' Society,' vol. iii, 

 p. 264. 



VOL. II. — PART I. 3 



