source of nitrogen. In the pumice soil, root nod- 
ules did not form on plants, and the response 
to nitrogen application was pronounced. 
The effects of nitrogen fertilizer on the pal- 
atability of silver fir twigs and buds to rodents 
were particularly significant in western Wash- 
ington (Gessell and Orians 1967). Terminal 
shoots which had responded to nitrogen appli- 
cation were severely damaged by small rodents 
in winter. However, adjacent unfertilized trees 
were unaffected. The change in feeding habits 
resulted from a 20-percent increase in nitrogen 
and protein content of the damaged parts. 
Plantings and _ Attractants.—Game _ food 
plantings serve a number of purposes; one is 
the augmentation of protein and the various 
dietary elements that may be deficient in na- 
tive vegetation during part of the year (Halls 
and Stransky 1968). Quality forage grown as 
supplement may be in the form of succulent 
green herbage, browse, fruits, seeds, or other 
plant parts or forms. There is little evidence 
that food plantings directly increase game 
numbers. As attractants, however, they can in- 
crease hunter success and facilitate hunting by 
drawing deer or other game to these concentra- 
tion points. ; 
One objection to plantings of introduced spe- 
cies is their artificial appearance in the natural 
environment. This is particularly true of cereal 
crops and other exotic plants. There are oppor- 
tunities, however, to use native species of high 
nutritional quality, and perhaps to develop 
strains of low to moderately palatable forage 
species. Selection of superior strains of juni- 
per, sagebrush, and other browse shows con- 
siderable promise for improving game ranges. 
Field studies have shown that individual na- 
tive plants vary in palatability. In Washington, 
salal is considered unpalatable in some locali- 
ties and as an important forage plant in other 
areas. Juniper utilization is related to the es- 
sential oil content of individual plants (Smith 
1959). Preferences for sagebrush are less obvi- 
ous than those for juniper. Likewise, on bitter- 
brush ranges, there is often wide variations in 
the degree of utilization among individual 
plants. These differences are probably inherent 
in the plants themselves; however, soils and 
other environmental factors may play a role. 
Selections of these and other species are being 
propagated and tested to a limited extent on 
important winter ranges. 
In a detailed investigation of palatabilitv of 
deer forage plants, Longhurst et al. (1968) 
found a generally positive correlation between 
palatability and digestibility. Grazing animals 
can and do select forage that has a much 
higher protein content than that of the aver- 
age forage on a particular site. Deer obviously 
select plants with high nutrient content; how- 
ever, it is unlikely that they can smell the nu- 
trients but may be responding to compounds 
not yet identified. Experiments in California 
involving sheep with aesophageal fistulas 
showed that selected grasses had 15 percent 
protein while grass clippings had only 8 per- 
cent protein. In another California study, 
rumen content of deer collected in October con- 
tained an average of 17.6 percent crude pro- 
tein, while clipped forage on the same area 
containing the same proportion of plant species 
had only 6.9 percent protein. Feeding studies 
showed very little increase in rumen protein 
over protein content of the forage before con- 
sumption (Bissell 1959). 
Lauckhart (1962) jointly discusses the evo- 
lution of plants and animals, noting that the 
most successful plants have been those of low 
nutritional value. These have been able to re- 
treat below the animal’s threshold of malnutri- 
tion and thereby escape total destruction from 
overuse. Lauckhart cites a recent experience 
involving introduction of the legume, colutea, 
on pheasant habitat. The first plantings were 
immediately damaged by rabbits and small ro- 
dents. Under intensive rodent control, colutea 
became well established on a sizeable area. 
When rodent control was terminated, the in- 
troduced legume was totally destroyed in a rel- 
atively short time. 
RESEARCH NEEDS 
The foregoing is a brief summary of what 
we know about forage quality as a tool in wild- 
life management. The degree to which this 
knowledge is applied on the ground depends on 
various ‘factors such as funding, work priori- 
ties, management objectives, and public sup- 
port. 
Despite the progress already made, a num- 
ber of research needs are readily apparent in 
the field of forage quality. These include: 
1. To determine if the high nutritive value 
of individual browse plants results from ge- 
netic characteristics or from soil or other en- 
vironmental qualities. If higher nutritive value 
is a genetic quality, we should be collecting and 
planting seed from these selected plants and 
perhaps developing special seed orchards of 
the superior strains. The development of supe- 
rior strains should involve high production and 
other desirable characteristics as well as nutri- 
tive qualities. 
2. To determine if forage quality declines 
with age on longlived shrubby plants. If there 
is decline, can this trend be reversed or halted 
by grazing or by some other treatrment? Is 
there a given level of forage removal that re- 
sults in the highest forage quality? 
38. The economic justification and manage- 
ment implications for wildlife clearings in tim- 
29 
