Foreword 



To the writer is allotted a little space to comment 

 on the map which faces the title page of this book- 

 let, and to make acknowledgment of the expert ad- 

 vice and assistance which has made it possible for 

 him to complete the task of putting together the 

 "Comprehensive List of Birds" with which the 

 greater portion of this booklet is concerned. 



The map defines for the first time the three divis- 

 ions of the state hitherto referred to as Northern, 

 Central, and Southern Illinois. It also illustrates 

 in color the faunal areas or life zones described by 

 Mr. Ridgway in the introduction to the list just 

 mentioned. The original idea as suggested by Mr. 

 Ridgway has been followed out by making the divis- 

 ional lines of separation between the stated areas 

 run as nearly as practicable along isothermal lines. 

 The isotherm selected in marking the separation 

 between the Northern and Central divisions is the 

 mean annual of 51 degrees, while that between the 

 Central and Southern is 55 degrees. The division 

 lines as they appear heavily shaded are made to 

 follow county lines. This procedure is somewhat 

 arbitrary but it is probable that it fairly approx- 

 imates the true boundaries, and there is consider- 

 able gain to students in the field by bringing out 

 geographic limitations so definitely. The Introduc- 

 tion to the Comprehensive Check List by Mr. Ridg- 

 way, which appears in its proper place, clearly sets 

 forth the significance of the zonal areas and their 

 importance in explaining the distribution of bird 

 life. Mr. Ridgway's discussion is a valuable con- 

 tribution to this subject. 



It remains to acknowledge the liberal support 

 and assistance given the writer in the preparation 

 of the Check List. For the contribution of notes, 

 observations, and items of interest, for original sug- 

 gestions and careful criticism, and for expert advice 

 and help in the actual preparation of the booklet, 



