PACIFIC FLYWAY 
SOUTHERN ALBERTA 
Weather and Water Conditions 
The spring of 1957 was the earliest we have witnessed 
since the beginning of these Canadian surveys. Phenologically it was two 
to three weeks advanced over normal with seeding of grain being possible 
in April in southern Alberta. This practice usually occurs about mid- 
May. Unseasonably warm spring temperatures in the 70's and 80's were 
responsible for this early season and forced vegetation so that aspen were 
leaved by early May. Many emergents were already at June heights when 
the survey began. 
While water conditions were not critical to the farmer dur- 
ing May, many areas were at or near the critical stage for waterfowl. 
The numbers of potholes dropped to the lowest figure for all strata since 
the beginning of our aerial surveys. In Stratum A the number of water 
areas was 47 percent below the 1956 figure and 48 percent below our six~ 
year average (Tables 1 and 2). Similar figures for Stratum B and C, 
respectively, show numbers of water areas to be down 26 percent and 29 
percent from 1956 figures and down 22 percent and 38 percent from the 
six-year average. With Stratum C losing 40 percent of its water areas in 
1956 and 38 percent more this year, it is not difficult to visualize the 
extent to which the drying trend progressed in southern Alberta. The 
number of water areas continued to decrease through the summer with the 
additional loss averaging 37 percent for the survey area (Table 3). 
Table 1 - Water Areas on Aerial Transects, May 1956 and 1957 
_ Strata A Strata B Strata C .Province 
1956 1957 1956 1957 1956 1957 1956 1957 
Ponds Per | 
Square Mile 16,00 8.45 22.91 16.88 7.18 5.06 16.59 11.05 
Estimated z 
Total Ponds 353135 186667 598024 442270 115702 81595 1066861 710532 
Change 47% 26% 29% ~33% 

21 
