RODENT SURVEY PROCEDURES
a. Rodent survey and ectoparasite survey are the first steps planning an
effective rodent control program. Methods of rodent control will be covered in Lesson 3.
This reason will be concerned with determining if a rodent infestation exists, the degree
of infestation, the species of rodent involved, and the ectoparasites present. A basic
understanding of rodent habits will give the surveyor a lot of valuable information.
Rodents, because of the way they live, furnish many details of their population to a
trained observer. The rodent will even give indications of its food preferences and other
intimate details of its personal life. When all of the data are collected and deciphered,
the control team will be led to the rodent nests, runways, sources of food and water.
b. In areas where rodent-borne diseases may constitute a problem, it is
recommended that specimens of the animals and their ectoparasites be collected and
examined for evidence of these diseases. Generally, two specific objectives must be
considered when conducting a survey of this type. First, the presence of the etiological
(causing) agent of the specific disease in the collected specimens; and second, the
population dynamics of the particular population. The two objectives can be satisfied
only if a comprehensive survey program is initiated. Knowing of the presence of an
etiological agent in a rodent population is of little value if the population density,
ectoparasite density, breeding habits, home ranges, and migration tendencies of the
population are not also known.
EVIDENCE OF INFESTATION
Observation of rodent signs is essential in ascertaining whether rodents currently
infest buildings, in determining the degree of infestation, and in planning effective
control programs. These signs are droppings, runways, tracks, burrows, nests,
damage, rat odor, live rats, dead rats, and damage to stored products.
a. Droppings. The most frequently observed sign of rat infestation is rat
droppings. (See figure 2-1). Rat droppings are rod shaped, with rounded ends. They
vary in size from one-fourth inch long by one-sixth inch in diameter to three-fourths inch
long by one-fourth inch or slightly larger in diameter. Droppings of young rats may not
be distinguishable at times from those of mice, although mouse droppings tend to be
more pointed at one end. When droppings of various sizes are found, the presence of
both adult and young rats usually is indicated. The age of droppings is an indication as
to whether a building currently is infested. Fresh droppings are soft enough to be
pressed out of shape and often have a glistening, moist appearance. Color varies with
the food eaten but usually is black or nearly black. Within a few days, depending on
climatic conditions, droppings become dry and hard. Later, the surface become dull,