MISSISSIPPI FLYWAY 
SOUTHERN MANITOBA - Continued 
Production Indices 
There is practically. no change in the brood index between 1957 and 
1958. On the other hand, the late nexting index (those birds seen as singles 
or pairs), used as an ined cation we continued nesting effort, increased 214 
indicating that considerable nesting was still taking place during the period 
of the survey. The age class distribution of the broods also bears this out. 
The percentabe of broods in age class l for both strata was the second 
highest for the years 1954 to 1958, averaging 51.5%. This indicates that the 
survey was conducted in the early part of the brood season for the bulk of 
the population and that there are probably more broods to come. 
There is no significant decreases in the late nexting index for any 
species. While this is probably a valid indicator of continued nesting effort 
for most species, it is probable that the nesting season of the canvasback was 
for all practical purposes over at the time of the survey. 
Due to the very conspicuous tendency this year for birds to moult 
on the potholes rather than in the larger marshes, there may be pre-moulting 
or moulting birds included in the index, even though every effort was made to 
record only singles and pairs. 
Coot broods showed a slight decrease from 1957, but the index is 
still well above the average. 
A table is included showing the trends since 1954. The duck 
brood index and late nesting index are the highest for the five-year period 
in both strata, while coot indices were exceeded only in 1957. 
Counts were made on 90 age class II and ITI broods that were 
judged to be complete. The number of ducklings per brood is considerably 
higher than that of previous years. 
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