EARLY SPRING ON THE MOORS 25 



when observations touch bed-rock : and that point is 

 not dependent on the vagaries of local weather. It 

 marks the commencement of that great vernal northing, 

 which is all but universal in the bird-world. That 

 movement (the general movement, I mean) is perfectly 

 recognisable, in the case of the three species named, 

 by the month of March- — frequently, in open seasons, 

 as early as the middle of February. But it needs close 

 observation and practised judgment to discriminate accu- 

 rately between (i) those irregular, unimportant local 

 movements first mentioned, and (2) the commencement 

 of the general systematic northward migration. 



The difficulty, moreover, appears at first sight to 

 be accentuated, owing to the two movements (the local 

 and the general) continuing to proceed simultaneously, 

 and side by side. 



Fortunately for the ornithologist who is striving to 

 solve these problems, there exist certain species, of 

 which the different climatic races may be distinguished 

 by differences in plumage ; or, to be accurate, by the 

 degree of development in that plumage. 



To take, as a specific example of my argument, the 

 golden plover aforesaid. This bird (as everyone about 

 the moorlands should know) acquires in spring a 

 different plumage for the breeding-season. The throat, 

 breast, and under parts — which were white during all 

 the autumn and winter — now become black. But the 

 degree and intensity of that black develop in precise 

 ratio with the degree of latitude — north or south — 

 where the individual plover was hatched, and whither 

 it is now, in March, returning to reproduce its race. 



The Borders form almost the southernmost point in 

 the nesting-area of the golden plover. Hence our local 



