to 
bo 
Table 31. Canvasback production in the Minnedosa study arca, 1961-72 





Pairs Nests hatched Nest success Ducklings 
Year per km* per km? Egys hatched (% ) per kin+ 
1961 2.3 (0.7 6.8 32 5.0 
1962 2.7 1.4 6.5 51 9.3 
1963 3.8 Or.43 5.8 60 13.1 
196-4 3,9 2k 6.3 70 17.4 
1965 4.1 1.9 6.0 47 11.6 
1966 3.1 2.1 7,2 66 14.7 
LOG7 207 1.3 5.4 50 7.3 
1968# 2.9 0.3 6.2 {) 1.5 
1969 2.6 LS 6.5 70 11.6 
1970 9.1 1.3 5.6 62 7.3 
1971 2.4 1.7 5.5 70 9.7 
1972 2.9 L.4 6.3 66 8.9 
Mean 2.9 1.6 6,2 D4 9.7 

#Only nest data collected south of Minnedosa were used in 1968 because of wide divergence of data obtained from nests west of Minneclosa. 
sive burning in fall 1966 (Fig. 13). Many hectares of cat- 
tail and bulrush nesting cover were burned over, Harvest 
regulations on canvasbacks were also relaxed during this 
period in all four waterfowl flyways (Reeves and Carney 
1976). 
Stewart et al. (1958:337). who summarized canvasback 
breeding population densities from aerial survey data 
(1953-56), found that populations on the Canadian prairies 
ranged from 0.5 to 1.0 bird/km?. Higher populations were 
found on Hay Lakes, Old Crow Flats, and Athabaska Delta 
in the north. From these data it appears that canvasback 
breeding populations were higher in the Minnedosa area 
than in other breeding areas that were surveyed. During 
years of severe drought this area consistently had higher 
breeding populations than did most prairie and parkland 
regions. 
It appears that the 1963-65 canvasback population on 
the Roseneath area was as high or higher than at any pre- 
viously recorded period (Dzubin 1952, 1955). By 1970 it 
Table 32. Reproductive success of canvasbacks by pair- 
brood and nest success methods on the Minnedosa study 


area. 1963-72 
Broods Adjusted 
per nest 
Total Total pair success 
Year pairs* broods® (%) (“%) 
1963 30 15 50 57 
1964 32 20 63 70 
1965 36 12 33 40 
1966 32 21 66 65 
1967 34 5 15 39 
1968 29 z 7 s 
1969 28 12 43 63 
1970 26 10 38 57 
1971 32 15 47 68 
1972 24 2 § 66 
Mean 30.3 11.4 37.0 53.3 


IBeat-out census, 
Table 33. Total estimated canvasback production in the Minnedosa District, 1961-72. 




Total pairs Hen success* Brood production Total ducklings 
Year per km” (“e) per km? Ducklings per brood per km* 
1961 2.3 32 0.7 5.1 3,9 
1962 2.7 51 L.A 5.0 7.0 
1963 3.8 60 2.3 4,4 10,0 
1964 3.9 70 2.7 4.7 12.7 
L065 4,1 A7 1,9 4.5 8.5 
L966 3 66 2.1 5.0 10.4 
1967 2.7 50 1.3 4.4 5.8 
1968 2.9 25 0.7 4,2 3.1 
L969 2.6 70 1.7 5.2 &.9 
1970 2.1 62 1.3 5.2 7.0 
1971 2.4 70 1.7 4.6 7.7 
1972 2.2 66 1.4 5.7 8.1 
Mean 2.9 56 1.6 4.8 7.7 

“Includes nest data from Shoal Lake area. 
