41 
In Area III, Class III broods average 6.5 ducklings, If total production was 
126 broods'then 819 young were reared to maturity by 358 pairs. Thus the original 
population of 716 ducks increased to 1535 or 114 percent, 
Because of the paucity of data on Class III broods on Area IV, class.IIB 
brood data is used to estimate production. If 501 pairs produced 102 broods whose 
over-all average size at the IIB age class is 7.9, then 806 ducklings were raised 
nearly to maturity from 102 broods. This population added to the original 1,002 
adults give us 1, 808 ducks or an increase of 80 percent over the breeding population. 
Expressed in another way, it took about 3 pairs of breeding ducks to produce 
a successful brood in Area III, 5 pairs to produce a successful brood in ArealV. 
In each area a serious predator problem exists as far as nesting is concerned. In 
the Lousana district, 53 percent of all nests destroyed could be attributed to avian 
and mammalian predators, in the Vermilion district, 66 percent of the nest 
destruction was from the same cause, 
Aerial versus Ground Coverage of Breeding Population 
an ne 
An aerial census of breeding pairs was flown on each study area in May. 
Attempts were made to coordinate the two methods so that counts made by both aerial 
and ground crews would occur close to each other in time. 
On Areal, the bald prairie, where edge and emergent cover is either non- 
existent or comparatively sparse, 91.3 percent of the waterfowl population was 
observed from the air. On Area II, a mixed prairie and cultivated district where 
‘emergent and edge cover is moderate in density, 42.5 percent of the population was 
observed from the air. On ArealIlII, a parkland district where 38 percent of all areas 
are considered to have "closed" edge types, 30.4 percent of the waterfowl were observed 
from the air. 
In Area IV, 21.7 percent of the population was recorded from the air. On this 
study area 56 percent of the ponds contained "closed" edge types. 
Table XX VI. - Comparison of Ground and Air Brood Vounts 
Ground Air Percent Seen by Air. 
Area II 20 12 60.0 
Area III 74 30 40.5 
ArealV 58 16 27.6 
During the brood count an additional factor enters into aerial observations, the 
density of emergent cover. At the time of the brood count 21] percent of the ponds on 
Area II were covered by emergents, 77 percent of the ponds on Area III and 62 percent 
of the ponds on Area IV were considered "closed" by emergents. 
Summary 
1. Water conditions were relatively poor on all areas at the beginning of the 
season. Heavy rains in June and July restored levels on the prairies and southern 
parklands and held those in the northern parklands to near normal. 
