OF NORTHERN ILLINOIS. 503 



The Ogle County list shows that but a small number of Sylvicolidce breed there in any 

 numbers, as my field of observation embraced the wide timber belt bordering Rock 

 River, as well as the adjoining prairie. I was also much surprised not to meet here with 

 Tardus fuscescens. Mr. Wm. Blackburn, an intelligent taxidermist of Rockford (111.), who 

 through a residence of many years and his profession has apparently become very familiar 

 with the birds of this vicinity, informed me that the warblers, even in the migrating season, 

 are never abundant, and that but four or five species (Dcndrceca virens, D. cestiva, D. casianea, 

 D. pennsylvanica, Setophaga rtdicilla) were really common. On the other hand, the "groves" 

 or forests skirting Lake Michigan, in Cooke County, seemed to abound with them to a 

 remarkable degree. They are perhaps more easily observed here from the fact that, through 

 the retarding influence exerted by the lake on the development of vegetation in spring, 

 they arrive before the buds on the trees are much swollen, and there is nothing to con- 

 ceal them. Again, the lake itself, and the peculiar distribution of the forests of the con- 

 tiguous region, may, and undoubtedly do, tend to deflect their course somewhat, and thus 

 crowd them together in their passage along the western side of Lake Michigan to the 

 forests of northern Wisconsin and the adjacent wooded regions further to the north. Dr. 

 Hoy has already called attention to the fact of the great abundance at Racine, one hundred 

 miles north of Evanston, of all the migratory birds, — that point, he observes, being ap- 

 parently a kind of rendezvous they make in their migrations. 1 



In the Cook County list the writer discusses at some length a question previously raised 

 by him respecting the validity of certain so-called species of North American Thrushes, 2 

 and gives his reasons for considering that there are but three species of the group in 

 question, instead of seven, the number given by Prof. Baird, in his Review of American Birds? 



A. — Ogle County. 



Turdid^;. 



1. Tardus migratorius Linn. Frequent, but not abundant. 



2. Tardus mustelinus Gmel. Common. 



No specimens of T. fuscescens Steph. were seen, though places apparently perfectly adapted 

 to them were not wanting. 



3. Seiurus aurocapillus Swain. Not uncommon. 



4. Galeoscoptes carolinensis Cab. Common. 



5. Harporhynchus rufus Cab. Common. 



SlTTID^. 



6. Sitta carolinensis Gmel. Common. 



Parid^. 



7. Parus atricapiUus Linn. Very common. 



8. Lophophanes bicolor Bon. Said to occur. Probably not common. None observed. 



1 " This city (Racine, Wis.) is situated at the extreme south- vous, that birds make during their migrations." Dr. P. R. 



em point of the heavy timbered district, where the great Hoy's " Notes on the Birds of Wisconsin." Proc. PhiL 



prairies approach near the lake from the northwest, and is a Acad. Nat. Sc, VI, (18o3). 



remarkably favorable position for ornithological investigation. 2 See Proceed. Essex Inst. Vol. IV, p. 56, (1864). 



It would appear that this is a grand point, a kind of rendez- 3 Review of Am. Birds, Part 1, p. 12, el .ieq., (1864). 



