16 



Bl'LLKTIX Ol' THIC 



caicd by the arrows. For example, the continuous breeding area ends 

 about Davenport, Iowa, on the Mississippi river, while an isolated colony is 

 found in the northward extension of this drainage valley at Red Wing, 

 Minnesota, (Louck, *95, p. 17; Roberts, '90. p. 2'AQ>). The occurrence of 

 the birds in southern Wisconsin will doubtless follow the same law. Up 

 the Illinois river valley above Ottawa, the bird occurs as a rare resident in 

 the vicinity of Chicago, and an isolated colony breeds abundantly in the 

 KanlAkee swamps of northern Indiana. Up the Wabash valley, above 

 Delphi, it seems to have spread into southeastern Michigan, and has been 



^ V^cuPtRl 



Fig. 1. Breeding area, shaded, of Prothonotary Warbler in Upper 

 Mississippi Valley. Stragglers and route of dispersal in* 

 dicated by broken lines and arrpws respectively. 



taken breeding .in Oakland County, l^iidiigan (A. B. Covert, May 8, 1S96, 

 South Lyon). From near the head of the Wa])ash, down the Mauniee 

 valley, others have spread along tlie south shore of Lake Erie to the 

 vicinity of Cleveland. ( Rutler, '«T, p. 1023). TW Prothonotary Warblers of 

 southwestern Michigan, reach tlve Stal-e by way of the Kankakee swamps of 

 nothem Indiajia. and these swamps are reached 1>y t^ie Illinois atid WaJiash 

 bottoms, or both, as stiggeste4 by Rutler. It is very significant to laotice 

 that the stragglers and the new colonies c(wtinne ii*p the valleys in which 

 tne species normally breeds. The map -of the breeding area is also a nutp 

 showing the path of spring migration, and also, in all probability tliae pa^lh 



