steps taken over each kind of situation. It was the original plan to devote 
a single year to these observations, dividing each of the successive sea- 
sons between the three sections of the state—northern, central, and 
southern—in such a way that we might have a detailed and carefully 
shaded picture of the bird life of each section in all four seasons of the 
year. This plan was carried through successfully for a year beginning 
August 29, 1906; and additional trips were made for special purposes dur- 
ing the late summer of 1908 and the entire summer season of 1909. The 
distribution throughout the state of the trips of the bird observers dur- 
ing these years is shown in the accompanying map. These trips, all taken 
on foot, aggregated 2,825 miles, and on them 64,685 birds were recog- 
nized and counted. 
Two brief papers have been published by the senior author on parts 
of the product of these trips, as preliminary examples of their use; one 
on “An Ornithological Cross-section of Illinois in Autumn,* and the other 
on “The Midsummer Bird Life of Illinois,’+ the first based on a trip 
across the center of the state from the Indiana line to the Mississippi 
River, and the second treating of the summer data of the year 1907. 
The widely separated residences of the present authors, one of us liv- 
ing in Maine and the other in Illinois, and the many engrossing preoccu- 
pations of both, have made it impossible until now for us to have the per- 
sonal conferences or to provide for the cooperation necessary to a com- 
plete treatment of our subject; and it is with pleasure that we at last 
find ourselves in a position to work together through the mass of tables 
long ago made ready, and to avail ourselves, in their discussion, of the 
copious field notes and valuable reminiscenses of Professor Gross, often 
quite essential to an interpretation of our data. We now hope to prepare, 
without undue delay, a series of papers, the first of which is here pre- 
sented. 
In SOUTHERN ILLINOIS 
Abundance of Birds in General—In the summers of 1907 and 
1909, statistical data of the bird life of southern Illinois were obtained 
by the methods above described, in the form of a record of the species 
of birds and the numbers of each found on 5,527 acres of land chosen 
entirely at random, and this showed that orchards were decidedly the 
favorite places of bird resort at that season and in that part of the 
state. While the general average number for the whole area studied 
was 768 birds to the square mile, the number to that area in the orch- 
ards traversed was 2,969—or nearly four times the general ratio. Wood- 
lands came next in density of the bird population, with 1,794 birds per 
square mile; yards and gardens third, with 1,339; and shrubbery fourth, 
with 1,054 to the mile. The high rank of yards and gardens as a 
bird resort was due mainly to the semi-domesticated English sparrow; 
and with this eliminated, orchards, open woodlands, and shrubbery— 
* Bul. Ill. State Lab. Nat. Hist., Vol. VII, pp. 305-335. 
7 Ibid, Vol. IX, pp. 373-385. 
