418 
other species of these classes had received accessions from the south 
in larger number than their losses by the northward movement. 
The bird list of the short trip from Bloomington to Champaign 
(March 19-21) gave further evidence of the advent of spring in the 
addition of the red-winged blackbird to the list of summer residents, 
and the number of species necessary to make up the 85 per cent. list was 
also increased from five to fourteen. The prairie horned lark, rusty | 
blackbird, junco, and meadowlark made up about half the total number, 
juncos and tree sparrows remaining to represent the winter residents. 
Much more definite evidence of the increased effect of spring conditions 
"is given by the ratios of the several residence classes as compared with 
those just given. Against 3.3 per cent of summer residents and less than 
1 per cent of migrants for the first half of March in northern Illinois, 
we now have 30.9 per cent. of summer residents and 14.4 per cent. of 
migrants during the second half of the month in central Illinois, while 
the winter residents remaining were 19.7 per cent. northern and 16.6 
per cent. central. The ratio of spring arrivals: (summer residents and 
migrants) on the central Illinois list was thus more than ten times that 
of the slightly earlier northern Illinois list, the ratio of winter residents 
being at the same time less than a sixth smaller—another illustration of 
the fact previously referred to that birds from the south come up in 
the spring migration earlier and in much larger numbers than those of 
the northern birds which are leaving for their summer homes, with the 
result that a wave of condensation rolls northward, to be followed 
presently, like any other wave, by a “trough” of diminished numbers. 
RESIDENCE Ratios, NUMBERS OF Brrps 
Permanent Winter Summer Migrant 
Northern Illinois, March 2-15 76.4 1Oe7 3.3 0.6 
Central Illinois, March 19-21 38.1 16.6 30.9 14.4 
THE Most ABUNDANT Brirps (85 PER CENT. List), BLoom- 
INGTON TO CHAMPAIGN, Marcy 19 ro 21, 1907 
Species No. of each cadet total 
0. 
Prairie horned lark 82 | 14. 
Rusty blackbird 75 12.8 
Junco 67 11.5 
Meadowlark 57 9.8 
English sparrow 32 5.5 
Bronzed grackle 28 4.8 
Crow 25 4.3 
Bluebird 25 4.3 
Tree sparrow 24 4.1 
Red-winged blackbird 22 3.8 
Song sparrow 19 3.3 
Flicker : 17 2.9 
Robin 14 2.4 i 
Prairie hen 13 2.2 r 
All birds per square mile, 543. 
