
83 
This, and the fact that the aerial crew recorded only three flying broods, indicate 
that the survey was not so late that significant numbers of broods were flying 
and lost to the records. However, bad weather in the form of persistent high 
winds undoubtedly served to depress the number of broods seen. 
Table VII shows the Straturn"A"' July population indices for 1951-1955. 
Comparisons on the basis of broods alone are of limited value. The factor of 
"potential later broods" is of some assistance in orienting the count in the total 
season's production. These birds presumably indicate the strength of continued 
nesting effort and broods to come. These two indices represent unknown per- 
centages seen of populations actually present, and the potential of the latter 
figure is unknown. Thus, these figures cannot be added but must be considered 
separately. With the exception of "potential later coot broods," these data show 
a decrease from 1954, although all are considerably higher than 1953. Compari- 
sons with 1951 and 1952 are difficult without data on "potential later broods"! 
(1951), or more knowledge of the effect of extreme fluctuation in the figure (1952). 
In 1954 and 1955, production surveys were also run in Stratum '"'B". 
Although duck densities there are low, it produces a large portion of southern 
Manitoba ducks due to its larger size. Table VIII shows population data from 
Stratum 'B". With the exception of ''potential later broods,'' there was a slight 
decrease from 1954. 
Table VII. - July Brood Indices - Stratum A, Manitoba Aerial Survey. 
Brood Index to Potential Coot Brd. Index to Potential 
Year Index Later Broods* Index Later Coot Broods* 
1951 33, 200 No Data No Data No Data 
1952 32, 100 4,600 No Data No Data 
1953 8,000 23,000 600 No Data 
1954 13,000 37,900 2, 800 5,100 
1955 11, 600 29, 100 2,100 7,400 
* "Potential Later Broods'"' consist of pairs, lone males and 
lone femates. In the case of coots, the figure consist 
of singles and pairs. 
Table VIII. - July Brood Indices - Stratum B, Manitoba Aerial Survey. 
Brood Index to Potential Coot Brd. Index to Potential 
Year Index Later Broods Index Later Coot Broods 
1954 14, 600 17, 500 3, 200 1,100 
1955 11, 200 20, 200 - 1,100 

