VI 



PAGE 



Discussion of Ecological Tables .- 284 



The Darters as an Ecological Group 285 



The Typical and the Non-typical .Species 285 



Association and Distribution 287 



Comparative Study of Tables and Maps 288 



Collections for Ecological Study 295 



Acknowledgments 296 



Explanation of Tables and Maps 298 



Associative Coefficients of Thirteen Species of Darters {Ellicoslonjincc) : 



In order of size of coefficients (Table I) 300 



In the order of the size of the coefficients of association of each species 



with Hadroplcrits aspro (Table II) 301 



Coefficient Table of the Four least frequent Associates (Table III) 302 



Coefficient Table of the Six most frequent Associates (Table IV) 302 



Coefficient Table of the Seven least frequent Darters (Table V) 302 



Local Preferences of Darters (Table VI ) 303 



ARTICLE IX. AN ORNITHOLOGICAL CROSS-SECTION OF ILLI- 

 NOIS IN AUTUMN. BY S. A. FORBES. April. 19o7 305-335 



Introductory 305 



The Field Method 306 



General Results of Observations 307 



The Fifteen most important Birds, Indiana line to Ouincy, August 



28 to October 17, 1906 (Table I) 309 



The Ei.ghtcen most important Native Birds, Indiana line to Quincy 

 (Table II) 310 



The Vegetable Covering of the Soil 310 



Crop Areas, Indiana line to Quincy (Table III) 311 



General Distribution according to Crops 312 



General Distribution of all Birds, by Crops, Indiana line to Quincy 

 (Table IV) 313 



The Principal Birds in each Crop 314 



Number of Principal Birds in Principal Crojis, Indiana line to Ouincy 



(Table V) 315 



Number of Birds per Square Mile in each Crop (Table VI) 315 



Percentage of each Species in each of the Principal Crops (Table VII) . .316 

 Ratio of each Species in each Crop to all Birds in that Crop (Table 

 VIII) 316 



The Principal Species separately 317 



English Sparrows 317 



Crow-blackbirds and Crows 318 



Meadow-larks 318 



Cowbirds 319 



Horned Larks 319 



Mourning-doves 320 



Goldfinches and Field-sparrows 320 



Summary for Principal Species 320 



