12 Among the Birds in Northei'ii Shires. 



of certain favoured northern shires, especially with 

 the object of bringing them out in contrast by their 

 comparative study. The ornithologist with a southern 

 experience, studying bird-life in a northern county — 

 say in Yorkshire, for example — will soon find that 

 the avifauna of the two areas, although it possesses 

 much in common, is in many respects different. 

 Birds that he was wont to find common in southern 

 haunts are rare here; others that were scarce in the 

 south, and which he was apt to regard even as 

 rarities, are quite common. Not a few species are 

 met with that are seldom normally seen in southern 

 haunts, and opportunities are afforded him of study- 

 ing the nesting economy of species, the breeding 

 areas of which are decidedly boreal. Then, again, 

 the change of latitude involves a change of climate, 

 especially in winter; slight, perhaps, it may be, com- 

 paratively speaking, but yet sufficient to influence 

 the habits and movements of birds in quite a different 

 way from those prevailing in the milder atmosphere 

 of southern haunts. Birds that sinor all the winter 

 through in these southern shires are silent here at 

 that season; others that are sedentary there are of 

 migratory habits in the wilder and colder north — 

 in obedience to those climatic influences that act 

 upon the food supply, and so on. The farther north 

 he goes the more acute will the contrast in avine 

 phenomena become; and in species common to the 



