52 
WATERFOWL BREEDING POPULATION AND PRODUCTION IN 
MANITOBA INVENTORY DISTRICT NO. 8 
William H. Kiel, Jr. 
For a second year, waterfowl production has been studied in Manitoba 
Inventory District No. 8. .One phase of the project is a study of methods of predicting 
and measuring production in pothole habitat. The sampling procedure and the district 
are described in Special Scientific Report: Wildlife No. 2 (1949). 
This report presents the breeding population and production data that are 
comparable for 1949 and 1950. 
Methods 
As in 1949, 12 transects, each composed of 100 potholes, formed the basis 
for sampling the waterfowl breeding population and production in this district, Ground 
transect breeding-pair and brood census methods used to obtain the data given in this 
report were the same as used in 1949, 
Other methods used to measure the breeding population and production are 
special-study potholes, quarter-section blocks, aerial transects, and ground transects 
of the Manitoba Game and Fisheries Branch. Special-study potholes represent a 
random ten-percent sample of the 1,200 potholes on ground transects. Ten quarter- 
section blocks, located adjacent to transects, are a means of comparing transect 
results with another method of censusing waterfowl populations. 
Aerial coverage of the district was intensified this year. Transects were 
flown at frequent intervals during the breeding season over the exact routes of ground 
transects. Another phase of aerial coverage involved east-west routes flown at two- 
township intervals across the entire district. 
Permanent ground transects of the Manitoba Game and Fisheries Branch 
offered a direct comparison with ground transects used in this study. 
Discussion 
In District 8, waterfowl were late in arriving on the breeding grounds 
(Figure 1). A few pairs of mallards and pintails were present on transects in late 
April, but there was no real influx of ducks until the first week of May. Thereafter 
the build-up was rapid with the peak in the breeding population coming about May 27. 
Figure 1 indicates that the peak in population was about May 25 in 1949. It is felt, 
however, that this peak in 1949 was caused by birds moving into southwestern 
Manitoba from the drought areas of provinces to the west, and that the peak of the 
normal breeding population in District 8 was about May 10. 
Table 1 compares the breeding populations for 1949 and 1950 and indicates 
an increase of 15-17 percent. In terms of total ducks, blue-winged teal and ruddy 
ducks made up 14.1 percent of the 17.3 percent increase over 1949. The increase 
in ruddy ducks is not reflected in the breeding-pair comparison because at the time 
of census most ruddies were still in courting groups. 
Table 2 is a comparison of production and age-class distribution of broods 
for 1949 and 1950. Broods of species not included in this table follow the general 
trend shown here. An indicated 34 percent decrease in number of broods was offset 
