FLUCTUATIONS OF FUR-BEARING ANIMALS 227 
He says: ‘‘I think there is sufficient proof that they do mi- 
grate. A question annually put to the Indians returned 
from the woods in summer or fall was, ‘What signs of marten 
have you seen?’ and where few of these animals may have 
been seen in the previous winter, I would be told ‘They are 
travelling north, south, east or west,’ as the case might be, 
and so definite was the knowledge that these Indians would 
go that winter to head off the wanderers, and they never 
failed to come in contact with them. These movements 
of large bodies of the marten go on in summer till the severe 
weather sets in, beginning again in March and continuing, 
so far as the males are concerned, till such time as the snow 
is not fit to travel on; and then on again during the summer. 
It is accepted beyond cavil by all northerners—that is, 
Hudson’s Bay hunters—that the hare, lynx, and marten do 
migrate, and the fluctuation in their numbers is not con- 
sidered to be caused by epidemics, save in the case of the 
hare. The rabbit is always numerous where lynx and mar- 
ten are plentiful, and it is looked upon as a sine qua non by 
hunters and traders that it is the following up the rabbit 
and hare that causes the migrations—that the migration is, 
in fact, quest of food.” 
That the migration of the marten and of the lynx is caused 
by the quest of food is a fact that cannot be controverted; 
_ the need of food is the explanation of the migratory move- 
ments of most animals, whether they occur among the in- 
sects, fishes, birds, or mammals. After the disappearance 
of rabbits in the northern woods the lynx and marten, in- 
creased in numbers, seek food elsewhere. Likewise the 
predatory birds such as hawks and owls migrate southward. 
But it is important that this migratory tendency should not 
be confused with the phenomenon of the periodic fluctua- 
tion. Migration is one of the earliest and most popular ex- 
planations of the disappearance of a species of animals, but 
like many popular ideas it is not founded on fact. That 
