206 
square mile respectively), as was also the cowbird (88 in corn fields and 
64 in the state at large). None of the eleven remaining “more abundant” 
species necessary to bring the total up to 82.5 per cent. of all the corn 
field birds, was present in greater number than 29 to the square mile, 
the ratio of the mourning dove. The heterogeneous composition of this 
list of fourteen species and the moderate average numbers of each in- 
corn fields suggests, indeed, that their presence there was “accidental” 
rather than purposive, and we find no evidence in our records, with 
the two exceptions mentioned, that there is any group of corn field 
birds, properly so-called. In other words, we can not say that the 
corn plant either profits or suffers from the visits of birds to the fields 
in which it is growing (again excepting, of course, the cowbird and the 
crow-blackbird) to any extent which we have been able to discover. 
PRINCIPAL BiRpDs PER Square MILE or Corn, 
SUMMERS oFf 1907 anD 1909” 
Species Southern| Central| Northern| 1907 | 1909 | Both 
years 
Quail 24 4 5 2 9 6 
Mourning dove 50 32 14 26 32 29 
Red-headed woodpecker 10 6 3 4 7 6 
Flicker 5 9 14- “i 12 10 
Prairie horned lark 6 29 16 - 20 19 19 
Crow 3 9 14 4 13 10 
Cowbird 15 213 2 6 141 88 
Red-winged blackbird 14 7 30 9 23 18 
Meadowlark 225, 7 2 10 9 9 
Bronzed grackle 32 133 206 60 188 138 
English sparrow 49 120 189 50 181 130 
Goldfinch 4 5 19 12 9 10 
Vesper sparrow 1 3 18 5 10 8 
Brown thrasher pet) 9 2 % 6 6 
Birps oN PLowEep GrouND 
Ground plowed for planting but not yet planted can scarcely be 
said to resemble any natural habitat, or be expected to serve as a place 
of assemblage for any definite group of birds, and our data, derived from 
three hundred acres of plowed fields, chiefly in southern Illinois, are in 
accord with this supposition. A record of 314 birds occurring on this 
area, equivalent to the very respectable average of 670 to the square 
mile, is attributable mainly to the prairie horned lark, which has an unex- 
plained but well-known preference for bare earth as a resting place. On 
plowed ground it was usually feeding. busily on tiny weed seeds lodged 
in the soil, as shown by its actions and by the contents of crops examined. 
It was more than twice as abundant in plowed fields (162 to the square 
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