76 

Drought conditions in southwestern Manitoba resulted in conditions at 
Whitewater Lake which appeared ideal for a severe botulism outbreak. Fortunately 
cool weather reduced this threat but even so, total losses this year were higher than 
any year since 1949, Several thousand ducks were victims. Whitewater Lake is now 
at its lowest level since the big drought of the mid-thirties. 
Breeding Population Trends 
The aerial data indicate no significant change in waterfowl breeding populations 
for Manitoba this year as compared to 1952 (see Table 1). A marked decrease was 
shown for strata A and B (-38 percent and -18 percent respectively). Stratum C on 
the other hand showed an increase of 200 percent which approximately cancelled out 
the loss in strata A and B. The mallard and scaup were responsible for the large 
increase in stratum C in Manitoba, The scaup is responsible for the 17 percent 
increase indicated for the Saskatchewan River Delta (stratum D). A total duck index 
by species for the various strata is given in Table II. 
Stratum A in Manitoba showed little change in species composition (Table IIT) 
with the exception of a small increase in scaup. The relative abundance of the 
mallard in strata B and C rose sharply this year over last. 
Findings on Manitoba Game Branch ground transects for a 3-year period are 
piven in Table 1V. Note that in Districts 1 and 8, where water levels were better this 
year than last, populations have increased whereas the reverse is true in the drought 
area. According to these transects, no significant population change has occurred in 
stratum A comparing 1952 and 1953. Additional trend information for Manitoba can be 
found in Kiel's separate report. Table V shows species trends in District 8 from 
1949 to 1953. Table VI gives similar information for the Roseneath Study Area, an 
above-average unit located in District 8. 
Success of the Season 
Aerial production surveys were limited to strata A and D due to the low densities 
prevailing elsewhere which made brood counting impractical. In both strata, sizeable 
decreases in production were recorded. However, ground studies revealed that a large 
percentage of this year's production appeared after the aerial counts were completed. 
We concluded that in southern Manitoba where water conditions had been good 
throughout the breeding season, total production was not far below the 1952 level. In 
that part which had been dry, however, it was considerably below the 1952 level 
resulting in an over-all decrease estimated at about 25 percent. 
The decrease in stratum D, evidently resulting from floods, could not be pegged 
accurately because a follow-up survey to determine late production could not be made, 
We do not know how the increased breeding populations fared in stratum C, 
Based on information at hand, total production in Manitoba in 1953 was moderately 
lower than in 1952. 
