130 THE WOELD OF LIFE 



statement of the ascertained facts as to these strange migra- 

 tions — from the work on Mammals by the late Sir H. Flower 

 and E. Lydekker — will prove interesting: 



" The -usual dwelling-place of the Lemmings is in the highlands 

 or fells of the great central mountain chain of Norway and Sweden. 

 South of the Arctic circle, they are, under ordinary circumstances, 

 exclusively confined to the plateaus covered with dwarf birch and 

 juniper above the conifer region, though in Tromso and Finmarken 

 they occur in all suitable places down to the level of the sea. The 

 nest is found under a tussock of dry grass or a stone, constructed of 

 dry straws and usually lined with hair. The number of young in 

 each nest is generally five, and at least two broods are produced 

 annually. Their food is entirely vegetable, especially grass roots 

 and stalks, shoots of the birch, reindeer-lichen and mosses, in search 

 of which they form in winter long galleries through the turf or 

 under the snow. They are restless, courageous, and pugnacious 

 little animals. AMien suddenly disturbed, instead of trying to es- 

 cape, they will sit upright, with their back against a stone or other 

 object, hissing or showing fight in a very determined manner. 

 (See Fig. 12.) 



" The circumstance which has given more popular interest to 

 the Lemming than to a host of other species of the same order of 

 animals is that certain districts of the cultivated lands of iSTorway 

 and Sweden, where in ordinary circumstances they are quite un- 

 known, are occasionally and at very uncertain intervals, varying 

 from five to twent}^ or more years, literally overrun by an army of 

 these little creatures, which steadily and slowly advance, always in 

 the same direction, and regardless of all obstacles, swimming across 

 rivers and even lakes of several miles in breadth, and committing 

 considerable devastation on their line of march by the quantity of 

 food they consume. In their turn they are pursued and harassed 

 by a crowd of beasts and birds of prey, as bears, wolves, foxes, dogs, 

 wild cats, stoats, weasels, hawks, and owls, and are never spared by 

 man; even the domestic animals not usually predaceous, as cattle, 

 goats, and reindeer, are said to join in the destruction, stamping 

 them to the ground with their feet, and even eating their bodies. 

 Numbers also die from diseases apparently produced by overcrowd- 

 ing. None ever return by the course over which they have come. 



