207 
mile) as any other species, the next in order being the mourning dove (77) 
and cowbird (49). These and four other species—the killdeer (58), 
robin and upland plover (34 each), and English sparrow (30)—together 
made up 86 per cent. of all the birds recognized on plowed ground. The 
occurrence here of two species of shote birds in some numbers (22 
examples of the killdeer and 14 of the upland plover) was probably 
due to their search for earthworms and insect larvae in the soft earth. 
Tue Birps oF THE SWAMPS 
Open swampy lands are so scarce in Illinois that in 1070 miles of 
travel made in the summers of 1907 and 1909, only 4.6 miles were over 
swamps. In the area of 83.66 acres thus covered, 258 birds, belonging 
to thirty species, were identified, an average of 1974 birds to the square 
mile—about two and a quarter times the general average for the whole 
state. Two thirds of the swamp area was in northern Illinois, and there 
more than three fourths of the swamp birds were found. All of our 
thirty speciees were represented in this northern list, while on the nine- 
teen acres of southern Illinois swamp there were but five species (the 
red-winged blackbird, crow-blackbird, meadowlark, dickcissel, and Mary- 
land yellow-throat) ; and in 234 acres in central Illinois there was but 
one—the red-winged blackbird. The six species of the following table 
made up 82.6 per cent. of all the birds identified in swamps. 
PRINCIPAL Birps oF ILLINOIS SWAMPS, 
SUMMERS oF 1907 anpD 1909 
NUMBERS PER SQUARE MILE 
Red-winged blackbird 1125 
Bronzed grackle 207 
Bobolink 130 
Quail 76 
Green heron 46 
Long-billed marsh wren 46 
Brrps OF THE OPEN Woops 
Our data concerning the woodland birds are rather meager, mainly 
because it was impossible to use our method of identification and enumer- 
ation in any except open woodlands of comparatively small trees, and 
the one hundred and twelve acres accurately covered consequently made 
too small and too special an area to be fully representative. Furthermore, 
the southern Illinois forest area surveyed was more than twice as large 
as that of all the rest of the state, and hence the forest birds of the 
southern section predominate strongly in our lists for the state as a 
whole. 
About half of the fifty species recorded from woods were distinc- 
tively forest birds, rarely if ever seen in the open fields, and especially 
adapted by habit, preference, and sometimes by structural endowment 
