73 
reliable study of summer populations can be made only when the same area is covered 
at frequent intervals throughout the course of a season." An early arrival at James 
Bay was considered necessary to locate a banding station and work on the brood census 
which ended on July 11. At the time it was thought that the brood data might be supple- 
mented with data on broods from the banding area, but only two broods were observed 
after July 11.. 
The number of golden-eye broods observed was too small to draw any conclusions 
regarding brood survival for this species. 
Of the sex ratios obtained in banding for various species and age groups, only 
those encountered among adult black ducks (high preponderance of males) and among 
adult pintails (high preponderance of females) differ significantly from a theoretically 
even ratio. It is occasionally possible for a banding station to favour one sex against 
the other in trapping samples of a waterfowl population, but it is not known whether or 
not this bias appears in my operations. It is, however, unlikely that this bias would 
shift importantly from one species to another. 
Summary 
A survey of waterfowl breeding grounds in the Lake Abitibi area of northern 
Ontario was made in connection with banding operations at Moosonee. An index of 
population abundance was obtained for waterfowl nesting in the area and the relative 
abundance of each species was determined. 
A brood census was attempted on the same area. The time involved was too 
short to observe broods of all species. 
Eight hundred and fifty-two ducks were banded near Moosonee from July 25 to 
September l. 
Combination of aerial and ground censuses are suggested as a means of 
evaluating waterfowl populations for the district; aerial censuses in the northern 
inaccessible areas and ground transects in the southern part of the district where 
good highways are available. 
