used them. TVA crews conducting growth removal on a large area were able 
to work only a limited part of it at any one time and this allowed birds 
to shift from one locality to another without being frightened out of the 
general vicinity. Thus, it can be concluded that the human-interference 
factor involved in TVA's malaria control operations is not seriously 
detrimental to waterfowl. 
Studies also were made to determine the effects of winter burning of 
vegetation useful to waterfowl. It was noted that winter burning did not 
kill perennial vegetation and even in the case of annual growth enough seeds 
were left on the ground to perpetuate the species the following season. 
Seed counts were made on a series of square~yard piots before and after 
burning some of the more valuable duck~food plants, mainly swamp smartweed 
(Polygonum hydropiperoides), largeseed smartweed (P. pensylvanicum), wild 
millet, and rice cutgrass. Burnings were classified as being light, mediun, 
or heavy. In light burns, stubbles remained. In medium burns, no stubble 
was left, but plant debris on the soil surface was not completely destroyed. 
In the case of heavy burns, all vegetation was destroyed and bare ground 
was exposed. However, heavy burnings were rare or almost non-existent on 
the TVA area, so observations on effects were confined to light and medium 
burns. In these, there was appreciable damage to seeds of native duckfoods. 
Losses from 9% to 20% occurred in seeds of swamp smartweed and approximately 
15% reduction was noted in wild millet. No loss was noted for largeseed 
smartweed, and very limited injury occurred in rice cutgrass. These studies 
based on 16 square-yard plots do not justify broad conclusions but they do 
indicate that light and medium winter burnings though causing some damage, 
do not severely harm duckfood values of marginal vegetation on reservoirs. 
Some compensation occurs when such burnings contribute to coppice control. 
If brush growth were not controlled, the marginal vegetation would include 
very limited quantities of food for ducks. 
Cutting and Filling 
TVA's malaria control has included the practice of eliminating gradual- 
sloping "feather-—edge" margins and replacing them with steep ones. Cutting 
and filling operations involve the use of heavy earth-moving equipment for 
raising and levelling-off shore platforms or terraces. They are made along 
the contour in backwater areas where there often are plants such as rice 
cutgrass, wild millet, and smartweeds which, when flooded, have much wild- 
life value. Consequently, these physical changes destroy useful vegetation 
and narrow down considerably the habitat for marginal growths. In one 
exceptional instance, the cutting and filling operations were advantageous 
to waterfowl since the shore platform was extensive enough to be seeded 
with Italian ryegrass (Lolium miltiflorum). For the most part, however, 
these cutting and filling operations for malaria control are harmful to 
waterfowl interests. 

There is a practical alternative to this practice. It is not only 
favorable to waterfowl but at the same time lessens anopheline breeding 
habitat. Investigations have indicated that the squarestem spikerush 
(Eleocharis quadrangulata), a desirable duck food, can be planted successfully 
