During the winter, many creatures are able to drastically decrease their body temperatures and energy use and enter a reduced state of metabolism. even though environmental temperatures may be well below freezing, these animals survive. this is due in part to their hibernation but most importantly to the fact that

a) they are covered with feathers.
b) water has a high specific heat capacity.
c) the ion concentration within their cells increases.
d) they pick a location that allows them to avoid freezing.