36 
April, the low resident predator population may have been swamped by the prey 
species and could not bring in reserves fast enough to hurt the first nests and 
broods of pintails and mallards, most of which were on the wing by July 15. 
Agriculture was probably the most serious cause of nest destruction. Some nests 
in standing and swathed grain that had over-wintered were lost during spring 
harvest. However, this spring harvesting operation delayed extensive plowing 
for summer fallow until most stubblefield nests of pintails had hatched. 
Brood Maturity 
The degree of maturity of the duck crop in July has much bearing on the 
chances for eventual success of that crop. We accept the number of Class II and 
III broods seen in the July air survey as evidence of maturity. 
1952 - 3.8 Class II and III broods per square mile(88 percent 
of the total) 
1951 - 1,2 Class II and III broods per square mile (90 percent 
of the total) 
Pintail broods were the most advanced: 94 percent of these were in 
Class III; 14 percent non-flying; 19 percent flying in family groups; 61 percent 
flying in large flocks. Mallards showed a greater spread in maturity. Class I 
and II broods predominated among other species with the shoveler most advanced. 
Potential Later Broods 
We accept lone drakes, single hens, and paired birds on our July 
transects as evidence of broods to come. Prospects this year were nearly twice 
as good as 1951. 
1952 - 1.2 potential later-broods per square mile 
1951 - 0.7 potential later broods per square mile 
This figure should reflect the success of the normally late-nesting species and 
also should tell us whether substantial second-nesting has taken place among 
mallards and pintails that had lcst first nests. An examination of Table IV shows 
that little re-nesting took place among pintails (mainly because of initial success) 
although there was a stronger second effort by mallards. That the large proportion 
of potential broods was of later nesting species is evidence of encouraging progress 
of this hatch. i 
Moulting Hens 
Usually the presence of large numbers of moulting hens in banding drives 
during the first half of July indicates that many first nests have been destroyed too 
late in the incubation period to permit re-nesting. This was not the case in 1952: 
Kerrobert, Saskatchewan Laura, Saskatchewan 
July 10 12 14 19 July 26 28 
Percent of Pintails Hens 3 8 12 29 44 38 
Total Adult Pintails 900 1,980 391 821 245 432 
This increase in pintail hens more than likely signified desertion of mature young 
by the hen, rather than loss of nests, since it coincided with general flocking of 
flying young. 
