Food and Cover Techniques 
Coexistent with study of the identity, distribution, and migration of 
animals from the inception of the Biological Survey, was research into their 
food habits, From this techrique have developved, partly because of actual 
relationship, and partly through accidents of administrative history, a 
number of other techniques for the improvement of environment and for the 
encouragement of desirable and the control of undesirable species, which are 
today the very warp and woof of the wildlife manager's art, 
Originally developed to throw light on economic valucs in relation to 
agriculture, horticulture, and aboard this work soon responded to the 
needs of wildlife management, although that term was then unknown. A compre- 
hensive report on the food habits of ‘ie bobwhite was published in the Year- 
book of the U. S, Department of Agriculture for 1903, This was revised in 
bulletin form and accompanied by accounts of 6 other species of quail in 1905, 
and in the same year a similer bulletin treating 12 species of grouse and the 
wild turkey was issued. Systematic research on the food habits of wild fowl 
was begun in the laboratory in 1905 and in the field in 1908. The first 
publication on wilé-duck food plants appeared in 1911, and it has been suc- 
ceeded by a number of papers on that subdject. 
.The technique of food-habits research involves laboratory analysis of 
the contents of the alimentary canals of collected specimens, of feces and 
regurgitated pellets, of food remains at dens, nests, and roosts, as well as 
all practicable field investigations of feeding habits and of the utilization 
of food supplies. Such studies yield data, not only on specific food habits 
but also on the local, seasonal, and general valuc of food itoms, that are of 
fundamental utility in wildlife management. 
Knowledge of the relative importance of the various constituents of 
wildlife subsistence naturally led to efforts to increase the more valuable 
kinds, These efforts developed in one direction into recommendations as to 
choice of kinds, as to care of propageting material, and as to where, when, 
and how to set out valuable wild-duck food plants. ‘Later , plants affording 
refuge shelter and nesting cover were included, and the technique, in 
effect, became one of general improvement of the environment of wild fowl. 
These recommendations were acted upon extonsively oe a long serics of 
years and resulted in great improvement of some properties (up to a tenfold 
increase by the financial scalc), and are now sorving as the basis of de- 
velopment and improvement of the vast new system of Federal migratory bird 
refuges (more than 200, totaling more than 2,500,000 acres, within the limits 
of the 48 States.) Recommendations as to the value of marsh and aquatic 
plants and as to methods of propagating them have been of valve also to a 
branch of the fur industry, namely muskrat farming. The demand for these 
plants, largely created by publications of the Biological Survey based on 
food-habits research, is the mainstay of a business of supplying propagating 
material that at times has attaincd considerable volume, 
In another direction data provided by the technique of food-habits 
research made possible tho proparation of a long serios of publications on 
rim 
methods of attracting birds, These were intondod primarily for people desir- 
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