THE VERNAL MIGRATION 23 



no visible or existing" reasons, climatic, economic, or 

 otherwise, which render such movement imperative. 1 



Whatever may be the primary cause of migration, 

 whether it arises from the old-time instinct I have 

 alluded to or otherwise, it is at least certain that it is 

 a deeply implanted and widely spread impulse through- 

 out the feathered tribes. On referring to the foregoing 

 list, it will be seen that as early as February the influx 

 of visitants from southern climes commences, and that 

 during that month and March the majority of the 

 typical moor-breeding birds have distributed themselves 

 over the border-hills. The plovers and curlew come 

 first, followed by larks, wagtails, gulls, and redshanks ; 

 all these having northerly winter ranges— and hence 

 comparatively short distances to come — are just what 

 one might expect first. The ring-ouzel, too, from 

 Southern Europe, follows close behind them. Of the 

 trans-Mediterranean group, the wheatear is the first 

 to arrive, some weeks in advance of the main bodies 

 of warblers, swallows, cuckoo, landrail, and, last of all, 

 the nightjar. But, as though to show how unsafe are 

 any general rules, the common sandpiper, which winters 

 in Spain, is among the later arrivals ; while the dunlin, 

 which swarms on our own coast throughout even the 

 most severe winters, usually allows the month of April 

 to begin before putting in a tardy appearance on the 

 moors. 



1 The grebes may perhaps be cited as to some extent, deviating from 

 this rule. All five British species are certainly most common, in the 

 Border-land, during winter ; and (with the exception of the Slavonian 

 grebe, which nests in Iceland), the majority seem to breed rather to the 

 southward than to the northward of their winter positions. 



