SOUTHERN ALBERTA ~ Continued 
the 1958 index. A significant decrease was found for blue-winged 
teal. This reduction amounted to 85 percent in the favored park- 
land habitat. Despite a sizeable increase in stratum C the pro- 
vincial index dropped 49 percent. Of the diving ducks, canvasback 
end redheads decreased - canvasback to a significant 45 percent. 
On the contrary the mallard continues an upward trend 
though somewhat blunted from previous years. The mallard has now 
assumed dominance in strata A and B and do-dominance in stratum 
C. Forty-one percent of observed waterfowl are mallards. Bald- 
pate and gadwall have made significant increases as have several 
of the minor species of puddle ducks and diving ducks. 
Late or early seasons are reflected to a degree by the 
lone male segment of the early nesting species. These data are 
summarized in Table }. 
Breeding populations based on gross indices gave 
figures equal to 1958. Actually the 1959 index represents a 
reduction from 1958 because the factors of visibility were 
greatly increased as ducks were concentrated on fewer water 
bodies and many of the potholes had bare mud-flats which offered 
little concealment. This increased visibility applies equally to 
broods. Normally aerial crews observe about 40 percent of the 
existing populations in Alberta, This year aerial crews were 
able to observe about 60 percent. 
Production Indices 
| Table 6 represents a summation of aerial production 
data for 1959. Gross indices show strata A, B, and C to be 61 
percent below, 51 percent below and 90 percent above last year, 
respectively. The increase of broods in stratum ©, because of 
the small numbers of broods represented, had little effect and 
the provincial index was reduced 48 percent over 1958. When the 
relative visibility of the two years is considered, the decreases 
for 1959 become even greater. The current indices are without 
doubt the lowest ever recorded for the survey area in Alberta. 
This reduction has been severe enough to affect all 
species, but perticularly our mallards, pintails and diving 
ducks. As a result, the fall flight from the survey area in 
Alberta could be reduced to approximately one-third of the 
flight of 1958, 
26 
