Hatem oe LD BeOwNe Bou Lin et TN 11 
they did prior to cultivation. Elimination of waste in cultivated grain and 
weed plants could result in food shortages for birds which could well be- 
come a major limiting factor.” In pointing up the need for further knowl- 
edge of the relationship of agricultural land use to bird populations, Dr. 
Scott says that present knowledge is incomplete except for certain game 
birds. “Without such knowledge we cannot forecast and prepare for likely 
changes in bird populations coming out of a more intensive agricultural 
program.” 
Single copies of the article may be obtained free on request to Dr. Thomas 
G. Scott, State Natural History Survey, Urbana, Illinois. 
fi ft ft 
A FOUR-YEAR SURVEY OF THE ECOLOGY OF LAND 
BIRDS OF THE CHICAGO AREA — PART ONE 
By Fioyp A. SWINK 
DURING THE YEARS 1955 through 1958 an intensive survey was made by the 
author of the perching sites of local land birds, and the data compiled on a 
mass statistical basis. Although data on food habits and nesting sites were 
also recorded, it was felt that the information on these subjects was too 
meager to draw valid ecological conclusions for any given species. The 
counties surveyed were Cook, Lake, DuPage, McHenry, Kane, Will, and 
Kankakee in Illinois; Walworth and Kenosha in Wisconsin; Lake, Porter 
and LaPorte in Indiana; and Berrien in Michigan. To give uniformity and 
ease of interpretation, a set of “ground rules” was set up as follows: 
1. Species in the vicinity of feeding stations were ignored. 
2. Species at nesting sites were ignored after the first observation, 
8. Species continually returning to the same area for other reasons were ignored after 
the first observation. 
4. Flocks of birds of the same species perched together at the same site were con- 
sidered as one observation, as it was felt that the recording of individuals in one 
flock would distort the final statistical evaluation of the ecological data. 
5. Special effort was made to visit varied habitats at varied seasons of the year to 
get as complete and as undistorted an ecological survey as possible. 
6. Data has been recorded on man-made perching sites (e.g., telephone wires) as well 
as natural perching sites, such as trees. 
7. The use of the abbreviation ‘“‘sp.’”’ is as follows: If a bird is seen perching in an 
elm tree, but distance prevents accurate identification as to whether the tree is an 
American elm or a slippery elm, the entry is made as “elm sp.” 
8. It is recognized at the outset that more observations were made of birds in exposed 
habitats than of birds in highly concealed habitats, and due allowance should be made 
for this in evaluating the data. 
9. No data has been recorded on species heard but not seen. All data is based upon birds 
actually seen perching upon the sites indicated. 
10. Flying birds are not recorded. 
11. Oceasionally an individual bird may be recorded twice, if it is observed to travel from 
one perching site to another kind of perching site, and if this movement was done 
under natural conditions and not induced by frightening the bird into movement. 
12. It must be remembered that certain perching sites are much more common than others 
(for example, cottonwood trees are much more abundant than sassafras trees), and 
due allowance should be made for this in evaluating the data given. 
13. No observation has been entered unless the author was certain of identification. This, 
of course, has eliminated a number of observations, especially where great distance 
was involved; but it is believed that strict adherence to this policy has resulted in 
a higher quality of data. 
14. Rare species have been excluded from the final tally where it was felt that the in- 
formation was too meager to be of statistical significance. 
“e 
