405 
in the seasonal extremes of the year, a view of which is necessary to 
an understanding of the transition periods of spring and fall. 
ACREAGES OF WINTER Birp SuRvEY or 1906 anp 1907 
= Southern Central Northern 
eee Illinois Illinois Illinois Syate 
Corn 229.75 876.12 683.93 1789.80 
Wheat 289.29 259.42 76.83 625.54 
Stubble 161.99 342.25 305.62 809.86 
Plowed ground 18.30 325.31 223.41 567.02 
Pasture 184.34 501.58 498.43 1184.35 
Meadow 114.34 198.48 305.00 617.82 
Swamp LRT Met Kee ete heats WW |e Avalon ele hae 22.27 
Woods 209.55 48.99 58.64 317.18 
Orehard 19.02 16.36 2.44 37.82 
Shrubs 33.09 11.66 17.95 62.70 
Waste and fallow 116.41 35.40 97.86 249.67 
Yards and Gardens 8.18 5.47 12.30 25.95 
Miscellaneous 15.87 17:72 34.80 68.39 
Total 1422.40 | 2638.76 2317.21 6378.37 
In the search for food and protection, the winter birds of the state 
(mainly seed eaters) were found in the largest numbers in corn fields, 
_ pastures, and woodlands—about a fourth of all in the first, a sixth in the 
second, and an eighth in the last of these situations. In numbers per 
square mile, the ratios were of course very different, corn fields, wheat, 
stubble, and pastures having about equal averages, meadows and fields 
of plowed ground considerably smaller, andthe tree and shrub associa- 
tion (orchards, woods, and shrubbery), nearly five times as many to 
the unit of area as the open country. Indeed, from our numbers per 
“square mile for the whole state it would seem that there are in winter 
but three classes of bird habitat, the open fields, the woods, wastes, and 
orchards, and yards, gardens, and shrubbery, represented in our survey 
by the very unequal areas of 5596, 605, and 89 acres, respectively; the 
first with 423 birds to the square mile, the second with 1153, and the 
third with 2676. 
To what extent the higher densities are related inversely to the 
smaller areas of the classes of habitats in which they occur, the birds 
characteristic of the less extensive habitats being found merely to con- 
centrate there, it is impossible for us to say. The same general rela- 
tions as to density ratios hold in the sections of the state taken sepa- 
rately, although differences of winter climate and the occasional occur- 
rence of flocks of juncos, tree sparrows, and Lapland longspurs so over- 
weigh the averages in many cases that the detailed figures have little 
significance. 
This disturbing effect of the gregarious habit of winter birds is 
illustrated by the enormous number per square mile found in the 5% 
