BIRD MIGRATION 129 



build and considerably smaller, measuring only 

 some 13 inches in length as against 16 to 

 17 inches in the case of the latter. The white 

 patch on the neck of the wood pigeon is en- 

 tirely wanting, being replaced there by bright 

 metallic green, nor is there any white on the 

 wings. The call-note, too, is distinctly different, 

 resembling somewhat that of the rock dove. 



We have seen that in the case of the stock 

 dove, as in that of the woodcock, there are no 

 changes in the country, apparent to us, to 

 account for its advent and stay ; we come back, 

 then, to the same conclusion, that we are wit- 

 nessing the result of pressure from congested 

 population, overflowing along the most natural 

 and easy lines. 



The whole subject of dispersal and distribu- 

 tion is full of interest and of difficulty. The 

 mysteries of bird migration, their extraordinary 

 journeys, the unfailing instinct that brings them 

 yearly seeking an approach, as some believe, 

 to their original place of origin, have a great 

 fascination. These migrations appear to pre- 

 cede the settlement of new breeding stations ; 

 a process that has been going on throughout 

 the centuries and in every department of the 

 creation, and one of which, now and then, as in 

 these instances, we catch a passing glimpse. 



