Direct Observations of Tamed Deer to Measure Their Consumption of Natural Forage 
O. C. WALLMO! and D. J. NEFF ? 
Knowledge of the preferences for and rela- 
tive consumption of forages by wild animals is 
limited because of the difficulties imposed by 
their wildness. Several disadvantages are pre- 
sent in the methods that have been commonly 
used—stomach and feces collections, observa- 
tion of wild animals feeding, measurement of 
use on the forage species, and offering of for- 
ages to animals kept in pens. To obtain infor- 
mation on forage preference and consumption, 
another approach, observation of tame animals 
feeding in the habitat of their wild counter- 
parts, has recently been developed as a re- 
search technique. 
This paper reviews the use of this technique 
with big game animals, and discusses problems 
in the acquisition and interpretation of data 
and methods of training and handling white- 
tailed deer and mule deer for such purposes. 
HISTORY OF THE TECHNIQUE 
Cory (1927) was perhaps the first re- 
searcher to obtain forage consumption data by 
closely following range livestock. Application 
of the direct observation method with livestock 
is discussed by Bjugstad et al. (see Bjugstad et. 
al. 1969 in this volume). With wildlife, of 
course, the obstacle is the disinclination of the 
animal to permit close observation. Several 
other workers * were all able to closely observe 
forage choices of tame or semitame deer or an- 
telope. But not until 1959 was an effort made 
to employ specially trained wild or domestic 
ruminants in a systematic research plan as the 
principal measure of the kinds and amounts of 
forage taken on rangelands. This was done in 
Texas by McMahan (1964) with sheep, goats, 
cattle, and white-tailed deer in experimental 
pastures grazed at different intensities by these 
animals. 
During 1962 and 1963, Watts (1964) used 
specially raised white-tails to determine forage 
consumption in relation to seasonal availability 
in hardwood forests in Pennsylvania. Healy 
(1967) continued this work in other areas in 
Pennsylvania. In connection with a multiple- 
use forest management research program in 
Arizona (Worley 1965), Wallmo (1964) and 
Neff (1966, 1967a, 1967b) raised and trained 
both white-tailed and mule deer to evaluate in- 
* Principal Wildlife Biologist, Rocky Mt. Forest and 
Range Exp. Sta., USDA Forest Serv.; central head- 
quarters is maintained at Fort Collins, Colo., in Co- 
operation with Colo. State Univ. 
? Research Biologist, Arizona Game and Fish Com- 
mission, Flagstaff, Ariz. 
*Lindzey (1943), Hahn (1945), Buechner (1950), 
Wallmo (1951), Dunkeson (1955), and Brown (1961). 
fluences on diet of vegetation changes resulting 
from various land treatments. The only compa- 
rable foreign work known by the authors is 
that conducted with red deer by Dcieciolowski 
(1966) in Poland. 
The advantage of using an approachable 
tame animal to determine forages taken on 
wild lands can be summarized in a statement 
by Dunkeson (1955) who had one very tame 
white-tail and one intractable captive: ‘Close 
observation of this deer made possible discov- 
ery of food preferences and use of forage 
which normally goes unseen. The other deer 
was too elusive to be observed on the brushy 
terrain.” 
The other conspicuous advantage is the con- 
trol the scientist can exercise over his sam- 
pling procedure. He, rather than chance, deter- 
mines the times and places from which data 
are acquired. Yet, if random times and places 
are a desirable feature of an experiment, they 
also can be introduced at the discretion of the 
investigator. 
COMPARABILITY OF TAME AND 
WILD ANIMALS 
Subjecting a wild animal to the confinement 
necessary to tame it inevitably alters its behav- 
ior and its experience with food. This has been 
a principal objection to the use of such animals 
for forage preference and utilization studies. 
For this reason, Wallmo (1951) did not ini- 
tially use the tame antelope available when he 
was attempting to observe the feeding of wild 
antelope. They had been nursed on cow’s milk 
and raised on hay, grain, tobacco, candy, and 
garbage. However, after observing them graz- 
ing with wild antelope for several days, it was 
apparent that they were distinguishable only 
by the tags in their ears, not by their behavior 
or forage choices. 
Likewise, Buechner (1950) concluded, ‘The 
semitame antelope instinctively selected the 
same principal plants in the same proportions 
as the wild animals...” McMahan (1964) 
said, “. . .observations were made on wild deer 
feeding in the same area as the tame animal. 
These comparative observations gave the im- 
pression that the gentle deer’s grazing habits 
were not different from those of wild deer. 
Both the tame deer and the wild animals ap- 
peared to eat the same browse and weed spe- 
cies.” Healy (1967) felt that “. . .the captive 
deer behaved in the same manner and exhib- 
ited forage preferences similar to those of wild 
deer.” 
While it can be speculated that prior nutri- 
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