134 
A total of 458 ducks were banded, with mallards comprising most of the 
total. Population counts revealed this species to be the most common during the 
banding period. Table 5 is a compilation of ducks banded by species, age, and sex, 
Table 5. -- Banding Record at Gray's Lake, Idaho, Summer of 1950 
Species Sex Adult Local Total 
123 42 417 
178 74 
7 
5 
Mallard 
Pintail 
21 
S| SZ} = 
Nun oy lo 
B-w./Cinn. Teal 






F 9 
G-w. Teal M l 
F l 4 
Gadwall M 
P F 2 - 2 
Redhead M 1 
F | 1 2 
Ganvasback °° 20 °*" 4k” aN Se ee ee pee ee ee 
F : 1 1 
Coot 2 > 
Total 315 143 458 
Summary 
1. The spring thaw occurred 10 to 14 days later at Gray's Lake 
in 1950 than in 1949. Water conditions were considered to be 
excellent for nesting. 
2. Duck counts indicated a decline of one-fifth in the breeding 
population of ducks from 1949 to 1950. The mallard population 
suffered the highest numerical loss. Mallards and pintails 
together made up approximately one-half of the total breeding 
population of ducks at the lake in both 1949 and 1950. 
3. Canada goose production at the lake in 1950 was calculated 
to be approximately 1,000 goslings. 
4. On the basis of marsh samples, the trend of nest abundance on 
the lake was downward between the 1949 and 1950 seasons. A 
17 percent lower nest density per hundred habitat acres of marsh 
was obtained in 1950 as compared to 1949. 
5, Nest and egg success data for 1950 was presented for 187 Canada 
goose nests and 2}3 duck nests. A lower egg success was recorded 
for both Canada geese and ducks in 1950 as compared to the previous 
season. . 
6. In 1949, 991 brood counts were made and only 490 in 1950. The 
-average brood size was generally lower for all species of ducks. 
Other than for unknown causes, the mink and marsh hawk were 
the major decimating factors observed. 
7. Of the 458 ducks banded this summer 417 were mallards. 
