chapman's bird-life of the borders. 319 



The migration of Birds, and their geographical distribution, is a 

 subject to which Mr. Chapman returns again and again, illustrating 

 his remarks by a diagram showing, what he terms, the ' overlapping 

 zone ' of those species which are seen in the district throughout the 

 year, and whose summer and winter range may thus be said to overlap. 

 We are in accord with him in his remark that the Golden Plovers, 

 which nest on the Northumberland moors, leave the district at the 

 end of the season, and that their place is taken by others of the 

 species coming from some distant locality. We are aware, however, 

 that this view is not shared by some ornithologists. Mr. Seebohm, 

 for instance, writes :* 'It not unfrequently happens that the breeding- 

 range of a species overlaps its winter range. Under these circum- 

 stances it is probably a rule, with scarcely an exception, that the birds 

 breeding in the overlapping part are residents, who never migrate at all.' 



In condemning the various theories of speculative naturalists 

 attempting to account for the periodical phenomena in connection 

 with migration, Mr. Chapman ventures to propound a theory of his 

 own. Assuming, in the first place, that the original centre of 

 dispersal of all life throughout the world was the North Polar 

 region, he would attribute the great migratory tendency to the north 

 to an innate perennial instinct which still continues to draw vast 

 numbers of the feathered tribes towards the fount which was 

 originally the universal home of all. Without attempting in this 

 place to enter into the subject, we can only say that migration, using 

 the word in the widest sense, cannot possibly be explained by any 

 one theory or set of facts ; it is a complex, many-sided and deeply- 

 involved movement, arising from a great diversity of causes and 

 effects, acting and re-acting on each other, but all working to the 

 same end. One author dwells too much on the passage of birds 

 from north to south and the reverse, as if these lines were absolutely 

 the only ones followed. Recent observations show that land birds, 

 which come to winter in these islands, arrive normally by an east to 

 west route, and often from points south of east, and more rarely 

 from those north of east. In the Spring also many of our summer 

 visitors, notably the Wheatear, follow these same lines. In fact, the 

 fly-lines followed by various species are infinite, and frequently 

 inexplicable, crossing each other at all angles, and leading in 

 directions which, with our limited knowledge, appear to contradict 

 all preconceived opinion. 



The illustrations are a pleasant feature of this book. Fifty-four 

 pen-and-ink drawings, reproduced by photo-zincography, intended, 



* The Geographical Distribution of the Family Charadriidae, p. 37. 

 Oct. 1889. 



