422 InLino1is NaturRAL History SurvEY BULLETIN 
value is brought about largely by local 
habitat changes. From studies made of 
seed production in 1941 by Low & Bell- 
rose (ms.) it is apparent that dry soil 
greatly lowers the seed productivity of 
rice cut-grass; furthermore, unless there 
is an inch or two of water over the root- 
stocks during the fall, those items, which 
also are a waterfowl food, are not avail- 
able to ducks. At several lakes where 
index values of rice cut-grass were ob- 
tained throughout the 3-year period, 
this plant ranked first at five and second 
Fig. 2.—Walter’s millet (Echinochloa Wal- 
tert) outranks Japanese millet in certain habi- 
tats as a food for migratory waterfowl in the 
Illinois River region. While its favorable posi- 
tion may be due in most instances to greater 
seed production, it may be due at times to a 
diet preference on the part of pintails and 
teals. 
Vol. 22, Art: 5& 
at four areas. A check of the environ- 
mental conditions of these nine areas 
revealed that the first five were more 
Fig. 3.—Nutgrasses 
group ranking fifth in 
(Cyperus spp.), as a 
value among Illinois 
River valley duck food plants, produce large 
quantities of minute seeds. Straw-colored 
cyperus (C. strigosus) is pictured here. 
favorable habitats for the plant than 
were the others. 
Walter’s millet, Echinochloa Walteri, 
fig. 2, approaches rice cut-grass in value, 
according to the index figures in table 
3. It is to be expected that, like many 
other plants, this species varies 1n value 
with the year and habitat, its value de- 
pending on its own seed production and 
the availability of other foods. Although 
Martin & Uhler (1939) regard the small- 
er seeds of this species less important 
as a duck food than those of wild millet, 
E. crusgalli, we believe that Walter’s 
millet may locally, in certain years, be 
the more valuable species. For exam- 
ple, at Clear Lake in 1940, Walter’s mil- 
let was slightly less abundant than wild 
and Japanese millets combined. How- 
ever, Walter’s millet amounted to 16.52 
per cent of the native food plant items 
taken from the stomachs of ducks shot 
at this lake, while wild and Japanese 
millets totaled only 9.24 per cent. 
We believe that the greater value of 
Walter’s. millet may lie in a generally 
heavier seed yield of this plant or in the 
fact that pintails and) tealsupretes the 
small seeds of this species to the larger 
ones of the other millets. We know that 
pintail and teal diets are made up of 
smaller seeds than are those of mallards, 
baldpates, gadwalls and the like, and 
that the number of pintail and _ teal 
