i6o THE MIGRATION OF BIRDS. 



this area are either exdusively insectivorous, or 

 subsist on a variety of animal food that cannot be 

 obtained during winter. Some of the most inter- 

 esting instances of nomadic migration are pre- 

 sented by the various species of Corvid.e that 

 frequent the Arctic regions. The Raven {Corvus 

 corax) keeps to the extreme north as long as food 

 can be found, and wherever a village or settlement 

 furnishes any regular supply of refuse, will brave 

 all the rigours of an Arctic winter wdth impunity. 

 The Siberian Jay {Perisoreus iiifaustus)^ one of the 

 most w^armly clad of all Arctic birds, keeps to the 

 northern forests, w^andering about to the more open 

 and cultivated districts during winter or unusually 

 severe w^eather, returning again as soon as sufficient 

 food can be found. The Magpie {Pica caudata) 

 and the Nutcracker [Nucifraga caryocatactes) dodge 

 about their Arctic haunts throughout the winter, 

 wandering hither and thither, and frequenting the 

 villages and the post-roads to pick up a living, 

 retiring; to their more accustomed haunts as soon 

 as the weather permits. None of these birds are 

 migratory in the strict sense of the term ; neither, 

 however, are they by any ,means stationary ; they 

 are birds at the mercy of circumstances — w^anderers 

 and nomads, either becoming gregarious at the 

 approach of winter, or remaining solitary or in pairs. 

 The Pine Grosbeak {Pinicola enucleator) is another 

 thorough nomadic migrant. It lives in summer 

 in the more open forest districts of the Arctic 

 regions ; in winter it gathers into flocks like other 



