many avenues of escape in case of danger. These houses are often
repaired and used for several winters in succession, but are vacated
on the approach of spring. During the summer the muskrat is, in the
main, a herbivorous animal, but in winter necessity develops its
carnivorous propensities and it feeds then mainly upon the mussels and
crayfish which it can dig from the bottom of the pond or stream in
which its house is built.

The bats pass the winter in caves, the attics of houses, and barns, or
in hollow trees, hanging downward by their hind claws. Motionless for
months they thus remain, and those in the more exposed situations are,
doubtless, frozen solid. Yet, in time, their blood flows freely once
again and they become as expert on the wing as though the year were
one continual jubilee of insect chasing, and frost and snow were to
them unknown.

All the carnivora, or flesh-eaters, as the mink, skunk, opossum, fox,
and wolf, are in winter active and voracious, needing much food to
supply the necessary animal heat of the body. Hence they are then much
more bold than in summer, and the hen yard or sheep pen of the farmer
is too frequently called upon to supply this extra demand.

[Illustration: A WOLF.]

But of all our animals it seems to me the birds have solved the winter
problem best. Possessing an enduring power of flight and a knowledge
of a southern sunny sky, beneath which food is plentiful, they alone
of all the living forms about us have little fear of the coming of the
frost. True, fifty or more species remain in each of the Northern
States during the cold season, but they are hardy birds which feed