ety of areas to feed from and plants to eat pre- 
sent our most challenging problems. 
Converting to Practical Values 
Stomach and fecal examinations indicate 
which foods are most important in the diet, but 
the foods on which the animals are subsisting 
are not necessarily the most preferred. The im- 
portant foods are palatable and nutritious to 
the animal and are abundant in the habitat, 
while the preferred foods are those that would 
be eaten in the greatest amount if all were 
equally available. Equating food availability 
with consumption has been presented in sev- 
eral ways. The most common way is the nu- 
merical rating obtained by dividing the per- 
centage use of a plant by the percentage of 
abundance. An index ratio of 1.0 for a food 
plant indicates utilization approximately in 
proportion to its abundance; a larger figure in- 
dicates a greater food plant value, and a 
smaller figure indicates a lesser value (Ward 
and Keith 1962; Van Dyne and Heady 1965). 
With the increased amount of data on the nu- 
tritional value of plants at the time of use, 
there is need for an equation that will consider 
this factor in the evaluation. 
The main consideration of any food-habits 
data is its practical value. Initial information 
on individual species was used in life history 
studies. Early bird work was centered around 
economic status. Many studies appraised ani- 
mal damage and predator-prey relationships. 
The more recent studies are evaluating the 
ecological relationships and management im- 
plications. The emphasis on range management 
research to find the best and most practical 
means to manage, improve, and maintain the 
productivity of forest and related lands used 
for grazing domestic livestock and optimum 
populations of wildlife have increased the im- 
portance of determining food availability, nu- 
tritional value, and use. 
CONCLUSIONS 
The value of knowing the foods utilized by 
animals is becoming very important under our 
present policies of land management and im- 
provement practices. To gain this knowledge, 
we are studying diets in relation to food availa- 
bility and nutritional value. 
The accuracy and value of the work depend 
on the judgment and training of the exam- 
iner. Proficiency is obtained by studying the 
foods available. Since most of the identifica- 
tions are made from small parts of plants such 
as seeds, leaves, flowers, or very small frag- 
ments, a good reference collection of available 
foods is required. This will include slide 
mounts and photomicrographs of cells for the 
microtechniques. There are no published refer- 
ences to cover all of the material encountered. 
Each worker must study known reference ma- 
terials and develop keys and recognition char- 
acteristics of his own. It is a good practice to 
have the examiner in the laboratory partici- 
pate in the field collections. 
The work is time consuming and challeng- 
ing. Good equipment, situated in comfortable 
surroundings, is conducive to good laboratory 
results. 
Fistula techniques of field collecting diet 
samples and subsequent refrigeration permits 
work with fresh materials. We are making 
progress in obtaining samples from wildlife 
species, and techniques are being tested. Use of 
telemetry for tracing, immobilizing agents for 
capture, helicopters for transportation, and 
stomach pumping and fistulas for collecting 
samples are all possible. 
The recent work being reported on the eval- 
uation and description of methods of analysis 
is encouraging. The point analysis method for 
clipped plots and fistula collections has been 
found accurate and practical. Microtechniques 
have proven accurate and useful, particularly 
fe identification of finely chewed or ground 
ood. 
Results of fecal analysis of ruminant ani- 
mals to determine food habits have not been 
fully evaluated. Until more evaluation studies 
are conducted, conclusions from fecal examina- 
tions should not be accepted without recogniz- 
ing the limitations of the method. Qualitative 
data are quite reliable, but quantitative data 
are more difficult to measure and need more in- 
vestigation. 
LITERATURE CITED 
Adams, L. 
1957. A way to analyze herbivore food habits by 
faecal examination. N. Amer. Wildlife Conf. 
Trans, 22: 152-159. 
, O’Regan, W. G., and Dunaway, D. J. 
1962. Analysis of forage consumption by faecal ex- 
amination. J. Wild. Manage. 26: 108-111. 
Aldous, Shaler E. 
1941. Food habits of chipmunks. J. Mammal. 22(1): 
18-24. 
156 
Baumgartner, Luther L., and Martin, A. C. 
1939. Plant histology as an aid in squirrel food hab- 
its studies. J. Wildlife Manage. 3: 266-268. 
Bear, G. D., and Hanson, R. M. 
1966. Food habits, growth and reproduction of 
white-tailed jackrabbits in southern Colo- 
rado. Colo. Agr. Exp. Sta. Tech. Bull. 90, 59 
pp. 
