136 ANNALS OF SCOTTISH NATURAL HISTORY 



THE MIGRATION OF BIRDS : A CONSIDERATION OF HERR 

 GATKE'S VIEWS. By F. B. Whitlock. (London : R. H. Porter, 

 1897.) Price 35. 6d. net. 



This is a brochure of 140 pages devoted, as its title implies, to 

 a critical examination of Herr Gatke's views on bird-migration as set 

 forth in his now well-known volume on the Ornithology of Heligo- 

 land. Mr. Whitlock deals with the subject under five heads, 

 namely: (i) Direction of the Migration Flight ; (2) Altitude of the 

 Flight, and Meteorological Conditions which influence Migration ; 

 (3) Velocity of the Flight ; (4) The causes of the Migratory Move- 

 ment, and what guides Birds during their Migrations ; and (5) Excep- 

 tional Migration Phenomena. (A Table of Contents to facilitate re- 

 ference to these chapters would have been a decided convenience.) 



Herr Gatke's theories speculations we had almost said on 

 several of these points are, we believe, pretty generally regarded 

 among ornithologists as decidedly extravagant and unsupported by 

 anything deserving the name of proof; but mainly, no doubt, from 

 generous motives, with which we fully sympathise, no adequate 

 criticism of them has previously appeared in this country, though 

 doubtless Dr. J. A. Allen's able notice in the American journal 

 "The Auk," for April 1896, is familiar to many of our readers. 

 Mr. Whitlock's pamphlet should therefore be welcomed by all who 

 desire to see the other side of the question placed before the public 

 in a manner worthy of its importance. To our mind there can be 

 little doubt on which side the balance of evidence lies. Before we 

 can believe with Herr Gatke that the majority of migratory birds, 

 contrary to all we know of their physical powers and organisation, 

 can suddenly, on two nights in the year, rise from the lower atmo- 

 sphere in which their lives are spent to an altitude of from four to 

 seven miles above sea-level, and there, in spite of the rarity, etc., of the 

 air, not only live, but put forth powers of flight far exceeding anything 

 they seem capable of when within our ken, before, we say, we can 

 believe this, some solid evidence of its possibility and necessity will 

 have to be adduced. 



But those who wish to see an ample and thoughtful discussion of 

 the objections to Herr Gatke's views, and the difficulties which 

 surround them, cannot do better than read Mr. Whitlock's little 

 book ; and along with it we would suggest the perusal of Mr. Eagle 

 Clarke's "Digest of the Observations on Migration," in which what 

 undoubtedly are the true bearings of meteorological conditions upon 

 migration are explained. W. E. 



