No. 500] MIDSUMMER BIRD LIFE OF ILLINOIS 515 



Meadow-larks per Square Mile. Summer, liH'7 



They varied also in abundance, in a very interesting 

 way, from the north to the south. One hundred of them 

 in northern Illinois were represented by 175 in central 

 and by 215 in southern Illinois. This variation was evi- 

 dently independent of any difference in the extent of 

 surface covered by the kinds of vegetation which they 

 most prefer, since the ratio of pasture, meadow, waste 

 and untilled lands taken together was considerably less 

 for central than for northern Illinois, although the 

 meadow-larks were 75 per cent, more numerous; and it 

 was only a fourth greater for southern Illinois than for 

 northern, although the meadow-larks were more than 

 twice as abundant. The cause of the greater numbers 

 southward, so far as I can see, can be accounted for only 

 rather vaguely as climatic. 



Much more difficult of even general or hypothetical ex- 

 planation is a curious difference in the observed abun- 

 dance of meadow-larks in pastures and meadows re- 

 spectively, in the three divisions of the state. In northern 

 Illinois there were 87 larks per square mile in pastures 

 to 129 in meadows; in southern Illinois there were 125 

 in pastures to 297 in meadows; while in central Illinois 

 this relation was reversed, the number in pastures being 

 274 to the mile, and that in meadows 189. That is, while 

 100 pasture birds were represented in northern Illinois 

 by 148 in meadows, and in southern Illinois by 242, in 

 central Illinois they were represented by only 69. Since 

 the southern Illinois observations were made in June, 

 those for central Illinois in J uly and those for northern 



