Figure 14. Weather ideal for mass migration. The map shows the wind and air-pressure 

 patterns at 7:30 a.m., November 7, 1947. Mass waterfowl migration reached its peak at 

 Delta just before sundown on November 6, when it was estimated that 100,000 ducks 

 crossed the Delta Marsh in one hour. At the same time heavy migration was noted on 

 other Manitoba marshes, and a mass movement over the Madison, Wisconsin, region 

 was reported by Aldo Leopold (letter). The broad nature of this movement is reflected 

 in reports of waterfowl biologists, presented at the Ninth Midwest Wildlife Conference, 

 showing that 1947's heaviest migration down the Mississippi Flyway occurred at this 

 time: Minnesota, November 6, 7; Wisconsin, November 6, 7, 8; Nebraska, November 6, 

 8; Michigan, November 8; Illinois, November 7, 8, 9; Indiana, November 9, 10; Ohio, 

 November 6, 10; Missouri, November 6, 7, 8; Kentucky, November 

 10, 13; Louisiana, November 11. 



