(3) Amount eaten. Knowing how much food and water rats and mice need is
valuable in control work. For example, it helps in determining the amount of poison to
put into bait material. Since rats and mice need only limited amounts of food and water,
enough poison must be used so that normal feeding will give them a lethal dose. The
average adult rat eats about 1 ounce of dry food a day and drinks 1/2 to 1 ounce of
water a day. Mice, because of their small size, need less than rats. They eat an
average of only 1/10 ounce of dry food a day and take an average of 1/20 ounce of
water in each drink. In cold weather, mammals normally eat more to maintain body
heat. In the very gregarious mice, however, huddling to keep warm cuts down trips to
food sources, and food consumption is decreased.
(4) Feeding habits. The feeding habits of rats and mice are sufficiently
different to make some differences in their control. All rodent species have regular
eating habits. Rats usually begin searching for food a little after sunset each day;
however, mice, being small and hard to see, may come out during the day whenever
possible. Rats all treat food much the same way once it has been found. Usually they
carry it to a hiding place before eating it. Rats and mice will eat in the open only if they
are starved, if no enemies are around, or if the pieces are too big to move to cover.
Rats will sample a large variety of foods until they find a food source they like. Then
they eat until they are full. Mice nibble and eat constantly, only taking a little food from
any one source. Hence, in efforts to poison mice a great many baits should be put out
quite close together to make sure that the mice nibble enough to kill them. Rats will
normally become satiated on one food and will no longer work to obtain it, although they
will work to some extent to get at other foods. Using a bait quite different from food
already available to the rat or mouse may increase the probability of the bait being
eaten. One approach is to make several different baits available. The one taken the
most readily will most like be best for poison baiting.
i. Senses. How well the rodents know the world they live in depends on the
keenness of their senses. Their reactions to control efforts are the direct result of their
perception. Knowing what things rats and mice can detect is of obvious value to
persons attempting to destroy them.
(1) Touch. Touch is one of the first senses useful to rats and mice while in
the nest. It is also important throughout life, especially since most often they operate in
the dark. In addition to the normal ability to feel, such as man has in his hands and feet,
the rodents have highly sensitive whiskers, or vibrissae, and guard hairs. At the base of
each whisker is a complex nerve net to provide a high degree of sensitivity. Rats and
mice seem to prefer running along walls or between things where they can keep the
whiskers in contact with the sides. This undoubtedly helps them travel in the dark
byways where they often live. The guard hairs are hairs that are longer than the others,
scattered throughout the rodent's fur. Apparently they are more sensitive to touch than
are the shorter fur hairs covering the body.
(2) Vision. Vision is not too well-developed in rats and mice, and apparently
they are color-blind. If rats are tested with different colors, they respond to brightness
but not to color. This can be helpful when using poisons for control. If there is danger
that human beings or birds might accidentally eat the bait, a warning color can be
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