18 
Table 25. Number of ducklings observed in canvasback 
broods by age classes in the Minnedosa study area, 
1961-728 
Age class 



Class I Class II Class III 
Year 0-25 days 26-53 days 54-65 days Total 
1961 6.0 (33)¢ 5.9 (55) — “(33 5.7 (90) 
1962 6.0 (59) 5.5 (45) — (Q) 5.8 (104) 
1963. 4.5 (71) 4.9 (28) — (0) 4.6 (99) 
1964 5.8 (125) 5.7 (141) 6 (11) 5.7 (277) 
1965 6.8 (81) 6.2 (62) 5. ip (8) 6.5 (151) 
1966 6.5 (177) 3.7 (111) 6.1 (17) 6,2 (305) 
1967 4.9 (79) 5.7 (41) 5.5 (6) 5.2 (126) 
1968 5.2 (40) 4.5 (24) 4.0 (1) 4.9 (65) 
1969 5.8 (126) 5.9 (90) 5.4 (25) 3.8 (241) 
L970 5.7 (64) 5.7 (33) — 5.7 (98) 
1971 5.5 (55) 5.4 (41) 4.1 (8) 5.3 (104) 
1972 6.8 (94) 6.1 (65) 5.1 (13) 6.4 (172) 
Mean 
and 
total 5.9 (1,004) 5.6 (736) 5.3 (92) 5.8 (1.832) 


aMean number of ducklings per brood including redheads, 
by]. B, Gollop and W. H. Marshall, unpublished report. 
¢Number of broods. 
Brood Habitat 
The number of wetlands present in the latter part of July 
averaged 147,6/km? along roadside transects and 168.4/ km? 
on beat-out areas (Table 29), The difference in the two 
values represents the number of wetlands not visible from 
the road. The mean loss in number of wetlands between 
early May and late July during the 12 years was 16% 
(Tables | and 29). Wetland loss during May to July was 
only 1.3% in 1969 and 1.4% in 1971. 
Table 26, Mean number of redhead ducklings in canvas- 
back broods in the Minnedosa study area, 1962-72. 
Class II 


Class | 



Canvasback Redheads Canvasback Redheads 

Year broods per brood broods per brood 
1962 59 0.3 45 ().3 
1963 7] 0.4 28 0.5 
1964 111 0.7 141 1.0 
1965 78 1.4 o6 1.7 
1966 148 0.6 LOG 0.7 
1967 72. 0.6 34 1,3 
1968 39 0.3 93 0.3 
1969 V7 0.5 54 0.7 
1970 58 0.3 34 0.4 
1971 51 0.5 39 0.9 
1972 84 0.9 61 1.4 
Mean Sl 0.6 59 0.8 




Table 27. Percentage of canvasback broods with redheads 
at hatching; and number of redhead ducklings per can- 
vasback brood (in parentheses) in the Minnedosa study 
area. 1963-72, 



Hatching dates 






Year 1-15 June 16-30 June 1-15 July — 16-31 July 
1963 19 (0.3) 32 (0.7) 35 (0.4) 8 (3.0) 
1964 32 (0.5) 35 (1.0) 35 (1.0) 67 (1.0) 
1965 17 (0.2) 51 (1.2) 61 (1.7) 88 (2.8) 
1966 25 (0.3) 2 (0.7) 23 (0.8) 0 (0.0) 
1967 8 (0.2) 3 (0.8) 43 (1.0) 0 (0.0) 
1968 14 (0.2) 25 (0.4) 0 (0.0) () (0.0) 
1969 24 (0.4) SOs 9) 13 (1.0) 38 (0.4) 
L970 30 (0.4) 3 (0.3) 24 (0.4) 50) (0.6) 
1971 § (0.1) ; (1.1) 33 (1.4) 0 (0.0) 
1972 35 (0.7) 6 (1.8) 45 (1.1) 30 (3.5) 




Table 28. Mean mortality of canvasback ducklings (redheads excluded) from hatching to Class II broods in the Minnedosa 
study area, 1961-72. 

Class I 
Class Il 


Loss. hatching to Loss. hatching to 


Eggs hatched Ducklings Class I Ducklings Class I 
_ Year per nest per brood (“%) per brood ( %) 
1961 6.8 Do 18.7 5.1 24.4 
1962 6.8 5.6 18,2 5.0) 26.1 
1963 5.5 4.1 29,3 4.4 23.7 
L964 6.3 5.1 18.9 4.7 25.5 
1965 6.0 5.5 .4 4.5 25.2 
L966 7.2 5.8 18.5 5.0 30.6 
1967 od 4.4 19.4 4d 19.6 
1968 5.6 4.9 lh 4.2 24.5 
1969 6.5 9.2 19.5 5.2 19,6 
L970 5.6 5.4 2.5 o.2 5.7 
1971 5.8 4.9 15,5 4,6 20.4 
1972 6.3 5.8 7.8 5.7 10.0 
Mcan 6.2 5.2 L.0 4.5 21.5 


