164 



Preface. 



visited Illinois territory. A few species (<?. g. Pica rustica had- 

 sonica and Lagopus alhus) are given upon the authority of Mr. 

 Kobert Kennicott, but have not been noted by any subsequent 

 observer. They may not now occur in Illinois, but this does 

 not, however, affect the validity of Mr Kennicott's record, which 

 cannot be passed over on the strength of purely negative 

 evidence. 



In the catalogue of 1874 I gave a list of 48 species "to be 

 looked for" in Illinois, and which it was stated would ''no doubt 

 be yet found to occur within the limits of the state." Of these 

 no less than 15 have already been taken or observed, besides 

 four [Dlchromajiassa rufa^ -^j'^'']''-'' 'i^osea, Pelecanus ftisous and 

 Stercorarius parasiticus) whose occurence had not been antici- 

 pated. We may therefore look with confidence to the capture 

 of the remaining species of the list, when the extreme southern 

 and northwestern borders of the state have been more thoroughly 

 explored. 



As may be seen from an examination of the following cata- 

 logue, the avian-fauna of Illinois is exceedingly rich and varied, 

 probably no inland state or territory, not traversed by lofty 

 mountain ranges, being equal to Illinois in this respect. This 

 great richness and diversity of bird-life results primarily from 

 two causes, — the central position of the state geographically, 

 and its great extent from north to south. The variety' of surface 

 which the state presents in different sections, notwithstanding 

 the prevalence of large prairies, is also an important factor, 

 no state, perhaps, east of the Pacific slope presenting greater 

 contrasts of this kind. Stretching through nearly six degrees 

 of latitude, the climates of the northern and southern portions 

 are very diverse, the advent of spring, as determined by the 

 first flowering and leafing of identical plants, averaging fully six 

 weeks earlier near the Ohio river than in the vicinity of Chicago.* 



§The difference in climate between Cairo and Chicago, as determined by the U. S. 

 Signal Bureau, is as follows: 



