Wildlife's Winter Diet
Nature Bulletin No. 659 December 9, 1961
Forest Preserve District of Cook County
George W. Dunne, President
Roland F, Eisenbeis, Supt. of Conservation
WILDLIFE'S WINTER DIET
Anyone who regularly feeds wild birds, and counts up the amount of
food that they eat in the course of a winter, often wonders how they
could get along without his help. In one day of freezing weather two or
three dozen small birds commonly clean up a half pound of food -- suet,
sunflower seed, cracked corn or small grain. This does not take into
account raids by squirrels and rabbits.
Winter in this region is a time of food crisis for all warm-blooded
wildlife. Most of our summer song birds, especially the insect eaters,
avoid cold by migrating to warm climates until spring. Likewise, most
waterfowl and shorebirds go south during the months when our waters
are locked in ice.
A few native mammals such as woodchucks and ground squirrels are
true hibernators. They prepare for winter by putting on extra fat which
they can draw on slowly during the cold months. In autumn they hide
away underground beyond the danger of freezing and "sleep" until
spring. Among these winter sleepers body temperatures often drop to 40
degrees Fahrenheit and their life processes are slowed to a crawl. In
dormant woodchucks, for example, the heartbeat can drop from 80 per
minute to four, and breathing from 25 per minute to once in five
The raccoon, opossum and skunk commonly hole up and stay quiet for
a few days or even weeks during extremely cold weather. Then they live
on their fat reserves but do not become cold-blooded. On warmer nights
they come out and forage actively even in midwinter. The raccoon feeds
on waste corn in farmers' fields, acorns and wild fruits, or searches the
shallows of unfrozen streams for crayfish. In addition to scavenging for
any kind of animal matter, the opossum eats wild fruit, The skunk hunts
meadow mice, ground-roosting birds, and digs among grass and fallen
leaves for hibernating insects.
Some animals hoard food for winter use. In autumn, chipmunks and
deer mice gather large quantities of nuts, wild cherry, basswood,
dogwood and other seeds which they store in their burrows. The fox
squirrel and gray squirrel bury nuts and acorns in the ground near their
den trees. In winter these are dug up and eaten, even through inches of
freezing weather sets in, the beaver gnaws down cottonwood,
aspen and willow trees, then cuts the branches into convenient lengths
and sinks them underwater for winter use. The muskrat feeds under the
ice on the roots and stems of cattails and other aquatic plants but it also
piles up special mounds of plants in early autumn which are eaten in
All of the winter birds and many of the mammals of our region face the
necessity of finding enough food each day to keep themselves alive and
warm until the next day. Their diet may vary from day to day and place
to place, depending on what can be found. Also, many have their own
likes and dislikes.
The meat-eaters -- hawks, owls, foxes, weasels and mink -- catch a few
birds but their mainstay is meadow mice and an occasional cottontail
rabbit. Both of the latter are strictly vegetarians. The mice scamper
about in a network of tunnels under the snow as they nibble on grass.
The cottontail munches on clover, tender plants, waste grain or gnaws
the bark from shrubs and young trees.
Weed seeds, wild berries and acorns offer an abundance of natural food
for the majority of our winter birds. Others search the trees and thickets
for dormant insects, their eggs and larvae.
The big black noisy crow is the cleaner-upper of our highways and
picnic areas .
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Update: June 2012