X 



Figure 11. Gauge for judging approximate 

 elevation of Mallard-sized duck. When the 

 page is held 20 inches from the eye, the 

 silhouettes (from top to bottom) show the 

 relative size of ducks as seen at heights of 

 ^^ 100 feet (good shotgun range), 200 feet 



(extreme edge of shotgun range), 500 feet, 

 1,000 feet, 2,000 feet, and 3,000 feet. 



■<*< 



"<<-< -*-<-<•< 



conforming to the breadth of Lake Mani- 

 toba. 

 ***** ***+. *+** m Usually the migrants from the north- 



west speed over the Delta Marsh without 



•-.. hesitation. On several occasions, however, I 



"•••• •... have seen them acknowledge their aware- 

 ness of the marsh by suddenly changing 

 flight formation and direction. After crossing the lake ridge from the north- 

 west I have seen members of a flock suddenly crowd together in a tight group, 

 like a band of blackbirds, appearing suddenly as a dark knot in the sky. These 

 flocks rise and fall, abruptly changing direction, east, west, and north again, 

 with stragglers swinging wide behind as in crack-the-whip. Sometimes one 

 cluster will join another. After some minutes of these gyrations, the groups 

 head south again, soon reforming into their normal strings. Once, on No- 

 vember 14, 1944, when a heavy migration arrived at Delta in weather very 

 cloudy despite a rapidly rising barometer, I saw what amounted to the whole 

 of an afternoon's migration "pile up" over the Delta Marsh, with hundreds 

 of bunched flocks flying in every direction, the sky so heavily loaded with 

 birds that we were sure a collision between bands would certainly occur. At 

 about six thirty the clouds broke — the first clear sky we had seen in two 

 weeks * — and the confusion ended, the migration resolving itself into a di- 



• The sun had set, but the patch of open sky, bright in twilight color, illuminated the dark 

 and stormy atmosphere. 



98 



