Table 2. Mean yearly number and area of May wetlands 
on transects, by size classes, in the Minnedosa study 
area, 1962-72. 

co 
Table 3. Mean yearly number and area of May wetlands 
on transects, by depth classes, in the Minnedosa study 
_area, 1963-68 and 1970-72. 
Area (ha) 







fois ied Number Area (ha) Depth - Number / 
(ha) Mean Per km? Mean _ Per km? class (em) Mean Per km? Mean Per km? 
0.3-1.2 766 14.7 79.4 1.5 0-30 334 6.6 31.6 0.6 
1-25 215 4.3 69.3 1.3 30-60 47] 9.3 105.3 2.0 
2,.5-5.0 166 3.1 106.1 a1 60-91 451 8.9 322.0 6.2 
5.0-12.4 167 ol 230.9 4.5 >91 125 2.3 159.2 3.1 
12,4-24.7 38 0.8 105.3 2.0 Total 1,381 26.6 616.4 11.9 
> 24.7 3 0.1 16.2 0.3 7 
Total 1,355 26.3 606.7 Ee 
Results 
Data on brood size were obtained from transects, beat-out Wetlands 
counts, and general observations on or adjacent to the study 
area. Counts of canvasbacks along roads were made 2-3 h 
after sunrise and 2—3 h before sunset. On cloudy days with 
light winds, counts were made during two 3-h periods, early 
and late. On clear days with moderate winds, only 2-h 
counts were made morning and evening. No counts were 
made during high winds or heavy rain. Broods on selected 
transects were counted by walking along the shoreline of 
each pond and flushing them into open water. A dog was 
used on ponds with wide bands of emergent vegetation. 
Canvasback broods were comparatively easy to count by 
the beat-out method or from roadsides because hens usually 
led their broods into the deeper, open water areas. One 
count per season was adequate to locate most canvasback 
broods. Canvasback ducklings require 8 weeks to attain 
flight stage, and by the time early broods reach that stage 
the eggs in the latest nests have usually hatched (Dzubin 
1959), 
Broods were classified by three age classes (I, 1 to 25 days; 
Il, 26 to 53 days; III, 54 to 65 days) described by J. B. 
Gollop and W. H. Marshall (unpublished report). Habitat 
data were recorded for ponds on which broods were 
observed. 
Table 4. Mean yearly number and area of May wetlands 
on transects, by land use types, in the Minnedosa study 
area, 1962-72. 



Number Area (ha) 
Land use type Mean Perkm? Mean Per km? 
Fallowed or plowed 731 14.3 327.2 6.3 
Stubble 228 4,2 104.1 2.0 
Ungrazed grassland 172 B30 63.2 1.2 
Grassland pasture 137 24 77.8 1.5 
Ungrazed woodland 28 0.4 7.3 0.1 
Woodland pasture 30 0.4 12.6 0.2 
Hay crops 25 ().4 10.1 0.0 
Grain crops 5 0.4 3.2 — 
Total 1,856 26.3 606.7 11.7 

In May, Type 3 wetlands were the most abundant on 
the study area, followed by Type 5 and Type 4 (Table 1). 
Two-thirds of the total acreage of wetlands was semiperma- 
nent (Type 5). The area of such wetlands ranged from 0.2 
to 4 ha. The reduction in sampling area starting in 1962 
resulted in deletion of all wetlands that exceeded 4 ha. 
Among the May wetlands, 72% occupied 0.4 ha or less 
and represented 24% of the total acreage (Table 2); 67 % 
(69% of the total acreage) ranged from 33 to 91 cm in depth 
(Table 3). Cultivated land surrounded 71% of the wetlands 
and represented 71% of the total acreage (Table 4). 
About 71% of the wetlands on the study area had both 
open shorelines and open surfaces during early May (Table 
5); 89% had open shorelines; and in about 5% , more than 
two-thirds of the shoreline was closed by aspen or willows. 
Among emergent plants, whitetop was the dominant 
vegetation in most of the wetlands (Table 6), although in 
Table 5. Mean yearly number and area of May wetlands 
on transects, by vegetative classes, in the Minnedosa study 
area, 1962-72, 


Area (ha) 
Number 

Vegetative class@ Mean Per km? Mean Per km* 
Open-open 967 18.9 501.8 9.7 
Open-half 150 3.1 38.5 0.7 
Open-closed 87 1.5 16.6 0.3 
Half-open 70 1.2 32.8 0.6 
Half-half 1] 0.4 3.7 0.1 
Half-closed 5 Tb 1.6 0.0 
Closed-open 48 0.8 9.3 0.2 
Closed-half 13 0.4 2.0 0.0 
Closed—closed 5 T 0.4 0.0 
Total 1,355 26.3 606.7 11.7 

“Proportion of the wetland surrounded by trees and proportion of 
water surface covered by emergent aquatics: shoreline-pond 
surface. 
bTrace, 
