THE LIFE OF MAMMALS 
until they reach the timber south of the Dobaunt Lakes, and 
find shelter and food. They are not known to wander south of 
the Churchill River. 
Half a century ago reindeer were similarly numerous but 
less regularly migratory all through northern Alaska," but 
now are rare there. Vast migrations used to occur in northern 
THE CARIBOU OF THE BARREN GROUNDS. 
Europe, for Nilsson a century ago described the serried masses 
of the traveling herds on the Norway fjalls as sometimes three 
and a half miles in width and packed as closely as sheep. 
That this is not exaggeration is shown by testimony from recent 
explorers of the Barren Grounds, especially the Tyrrell brothers 
of the Geological Survey of Canada (see Report, 1896). Food 
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