34 J. E. LITTLEBOT — THE MIGRATION OF BIEDS. 



Without pretending to advance anything that is very novel or 

 sensational, I venture to submit to you the following propositions, 

 as embodying the views which I have already expressed and 

 affording a proximate, or, at any rate, a possible solution of the 

 problems at issue : — 



(a) Birds migrate southward in the autumn because they are 

 compelled to do so by the exigencies of life, and hereditary im- 

 pulse or instinct teaches them, in some instances, to anticipate 

 the inevitable. 



(b) Birds migrate northward in the spring because the districts 

 to which they resort are not only their breeding-haunts, but their 

 " natural homes," and hereditary impulse or " home instinct" im- 

 pels them to return to the localities of their birth. 



It only remains for me to notice, as briefly as I can, the modus 

 operandi by which migration is conducted. The manner in which 

 birds migrate from north to south, and from south to north, to- 

 gether with the many variations which frequently occur, is a 

 subject that has recently claimed the special attention of ornitho- 

 logists. At their Swansea meeting the British Association ap- 

 pointed Mr. Harvie-Brown, Mr. John Cordeaux, and Professor 

 Newton, a Committee " for the purpose of obtaining observations 

 on the migration of birds at lighthouses and lightships, and of 

 reporting on the same at York in 1881." The report of these 

 gentlemen was read by Mr. Cordeaux at the York meeting in 

 September last. Returns were obtained from 103 stations on the 

 coasts of England and Scotland, the detailed particulars of the 

 returns being embodied in a separate report published by Sonnen- 

 schein and Allen. To these reports ; to the interesting work on 

 the ornithology of Siberia by Mr. Henry Seebohm ; to a paper on 

 the spring migration of birds at St. Leonards by Mr. J. H. 

 Gurney, jun. ; and to other information most kindly supplied to me 

 by Mr. Cordeaux and Mr. Seebohm, I am mainly indebted for the 

 facts I am about to lay before our members. 



It seems to be generally admitted that migration takes place, for 

 the most part, at high elevations, not unfrequently beyond the 

 range of human vision, and that birds migrate by sight, and not, as 

 has been assumed, by blind instinct. " If," writes Dr. "Weissmann,* 

 " there were an unknown something within them which showed 

 them that the land of their desire lay in tliis or that direction, then 

 they would fly straight to the goal, over hill and vale, sea and 

 river, to the place of their destination. But this they do not do. 

 On the contrary, they follow all the sinuosities of coast or river ; 

 they go up a certain valley, cross a mountain-pass at one exact 

 spot, and descend on the other side into another valley, bending 

 their course to all its windings." 



There are numerous facts which throw important light upon this 

 subject. The lines of migration which are adopted by diff'erent 

 species of birds have been mapped out in a very ingenious manner 



* ' Contemporary Review,' vol. xxxiv, p. 548. 



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