Figure 18. Deflection of blackbirds around Lake Manitoba, showing migratory divide at 

 southeast corner of lake and the coastal hiatus on the west shore. All hawks, Flickers, 

 and all Crows and other passerines follow the same leading lines of the lakeshore, split- 

 ting their migration to go up the east shore or around the south end of Lake Manitoba 

 In reverse migration the direction of travel is directly opposite to that shown here. 



same morning Pete Ward and I saw them branching away from the lake at 

 the mouth of the Whitemud River, but when we carefully surveyed about 

 30 square miles of the farmland along the west shore and on Big Point to 

 the north we saw not a single blackbird. Moreover, Ralph Thompson, a 

 farmer on Big Point, told us that so far that spring he had seen only one 

 flock of blackbirds, although at Delta they had been passing through steadily 

 for ten days. 



Just as there is a steady flow of these migrants westward around the 

 south end of Lake Manitoba, so there is another concentrated lane of travel 

 going northwest along the east shore. In short, there is a major migratory 

 divide at Lake Manitoba where the flight, arriving on a broad front, is split, 

 some flocks going one way, some the other. This divide is at the southeast 

 corner of the lake. Peter Ward and I watched this southeast shoreline during 

 a heavy blackbird migration on the morning of April 26, 1951. Flocks ar- 



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