39 



and lakes, bring forth young frequently on the way, are killed 

 during the course of the summer in thousands by men, dogs, cats 

 and all kinds of predaceous animals and birds, die in masses of an 

 epidemic, which always makes its appearance, where the con- 

 dition of a species of animal is disproportionately large, and by the 

 arrival of autumn the hosts are already considerably diminished 

 in number. In the course of the winter most of them die, and 

 in the second year after the beginning of the emigration, there is 

 seldom a living Lemming to be found remaining in the valley 

 bottom. Not one individual returns alive to the high Fjelds. 



But it is not only this species which has a mass increase in 

 these years. Simultaneously other small rodents, especially 

 of the genus Arvicola, increase beyond the normal number ; 

 thus in Finmarken the Gray-sided Field-Mouse (A . rufocanus), 

 upon the high Fjelds the Mountain Rat (A. ratticeps), in the 

 forest districts the Forest Lemming (My odes schisticolor), and the 

 Bank Vole (A. glareolus), or upon the lowlands the common A. 

 agrestis ; yes, even the Shrews, the Hares, and the Ryper are 

 wont to be more numerous in these years than in others. 



Then come also all kinds of raptorial birds and carnivorous 

 animals, springing as it were from the ground, enticed to the 

 place by the profusion of food. The mountains swarm with 

 various hawks, especially Rough-legged Buzzards (Archibut&o 

 lagopus) and various species of owl ; especially Short-eared Owls 

 (Asio brachyotus) and Snowy Owls ; and Gyr-falcons (Hierofalco 

 gyrfalco) now show themselves comparatively frequently. Among 

 the predaceous animals are Arctic Foxes, Stoats, and Weasels, 

 ubiquitous everywhere ; and they all live almost exclusively on 

 the Lemmings. Even the fish are among their enemies; one 

 may, not unfrequently in such a year, come across a trout with 

 its belly distended by a Lemming, which the voracious fish has 

 swallowed, while it was essaying to cross a river or lake. 



Even among the raptorial birds the prolificness of the year 

 leaves its traces. The Snowy Owl (Nyctea scandiaca), which in- 

 habits all the mountain plateaux of the country right up to North 

 Cape (and Spitzbergen), but which in ordinary years is found 

 scattered and sparingly, is, during these breeding years, so 

 numerous as to be scarcely absent from any part of the mountain, 



