Table 8. Number of breeding canvasback pairs on the 
Minnedosa study area, 1962-72. 
1] 
Table 10. Canvasback pair use in relation to pond size in 
the Minnedosa study area, 1962-72. 


Total pairs 


Date Drakes: Pairs No. 

No./km?* 
24-25 May 1962 70 7] 141 OT 
10-15 May 1963 101 94 195 3.8 
11-15 May 1964 110 93 203 3.9 
24-28 May 1965 132 78 210 4.1 
22-23 May 1966 SO 82 162 3.1 
99-23 May 1967 72 66 138 But 
9-10 May 1968 54 96 150 2.9 
21-22 May 1969 112 20) 132 2.6 
22 May 1970 74 36 110 2.1 
24 May 1971 92 30 122 2.4 
20-21 May 1972 79 33 112 22 
Mean 89 64 152 2.9 


Habitat Use 
Type 5 wetlands were used most by canvasback breed- 
ing pairs, followed by Type 4 (Table 9). Of all pairs re- 
corded on transects, 83% were on Type 5 wetlands and 
less than 0.5% on Type 1. Although 57 % of the wetlands 
on the study area amounted to 0.2 ha or less, the greatest 
use by canvasbacks was of wetlands between 0.4 and 2 ha 
(Table 10), Wetlands within these size classes contained 
55% of the total wetland area. Water depth exceeded 
91cm in9% of the wetlands, but because most of these wet- 
lands were large they made up 26% of the total wetland 
area and were used by 30% of the breeding pairs (Table 
11). Highest use per hectare was on wetlands more than 
0.6 m deep. 
Type 4 and 5 wetlands surrounded by plowed fields were 
used by 50% of the pairs: such wetlands made up 54% of 
the total wetland area. About 24% of the pairs used wet- 
lands located in pasture—a use per unit of area considerably 
above the mean (Table 12). Open water wetlands were used 
by 88% of the pairs (Table 13), Wetlands with open sur- 
faces were used more heavily than those with appreciable 
amounts of emergent vegetation. Pair use per hectare was 
highest on wetlands with half-wooded shorelines and open 
water surfaces. Breeding pair use was highest on wetlands 
dominated by hardstem bulrush (Table 14): wetlands con- 
taining cattails ranked second, and open wetlands con- 
taining no emergents third, 
Table 9. Canvasback pair use in relation to wetland 
type in the Minnedosa study area, 1962-72. 



Area (ha) 
Q-0,.2 116 
0.2-0,4 164 
0.4-0.8 347 
0.8-2.0 644 
> 2.0) 412 
Total pairs 
Pairs per wetland ha 
0.1 
0.2 
0.3 
0.3 
0.3 



Table 11. Canvasback pair use in relation to wetland depth 
in the Minnedosa study area, 1963-72.4 

Depth (cm) 
Total pairs 
Pairs per wetland ha 


0-30 10 
31-61 132 
62-91 924 
>91 451 
0.0 
0.2 
0.3 
0.3 


“Depths not recorded in 1969. 
Table 12. Canvasback pair use in relation to land use in 
the Minnedosa study area, 1962-72. 

Land use type Total pairs Pairs per wetland ha 


Grassland pasture 345 0.4 
Wooded pasture 59 0.4 
Ungrazed woodland 27 0.4 
Ungrazed grassland 183 0.3 
Plowing or summer 
fallow 839 0.2 
Hay crops 23 0.2 
Stubble 207 0.2 



Table 13, Canvashack pair use in relation to cover type in 
the Minnedosa study area, 1962-72. 
Cover type® Total pairs Pairs per wetland ha 

Open-open 1.476 0.3 
Open-half 66 0.2 
Open-closed 7 0.1 
Half-open 115 0.3 
Half-half a 0.1 
Half-closed | 0.1 
Closed-open 14 0.2 
Closed-half ] 0.1 
Closed—closed 1 ().2 


#Shoreline-pond surface. 
Table 14. Canvasback pair use in relation to emergent cover 
in the Minnedosa study area, 1962-72. 

Emergent vegetation Total pairs Pairs per wetland ha 

ati. ms Shee i Fike tig th ahah Hardstem bulrush 438 0.4 
MN etland type Total pairs Pairs per wetland ha Cattail 989 0.3 
] 7 0.0 Mixed 386 (),2 
3 82 0.1 Whitetop 179 0.2 
4 23] 0.2 Willows 6 0.1 
5 1,363 0.3 None 385 0.3 








