56 

with the 8.2 acres average size for Class B areas. Water conditions were satis- 
factory until late June when normal drying up of areas reduced the total number 
to 171 (Figure 2). However, a deluge in early July reflooded all areas, thus 
insuring an adequacy for late broods. 
Water gauges were installed in 33 ponds selected by their degree of 
permanence and location within the area. These were read approximately twice 
monthly and changes in water levels plotted (Figure 3). Generally, the more 
permanent ponds exhibited lesser fluctuations than the more transient water areas. 
The Breeding Population 
All species of waterfowl nesting on the area were present upon our arrival, 
Four breeding pair counts were completed on the area between May 6 and June 6. 
Notes of grouped ducks, such as two or more males together, or unpaired males 
and females together in a flock, were kept but these were not included in the calcu- 
lations for the breeding population. Since breeding and nesting activities of the 
various species are not synchronized, we did not feel that any one census could be 
utilized in determining the breeding population for all species present. Thus, we 
selected the count that we felt was best representative of the breeding population 
for each species. This selection was based upon observations of migration and 
nesting progress, and upon noted tendencies of ducks to gather on certain water 
areas. The corrected breeding pair count totalled 861 pairs, or an average of 76.9 
per square mile (Table III.). The pintail made up 30.8 percent of the total popula- 
tion and was closely followed by the mallard representing 27.2 percent. The only 
other two important species numerically, the blue-winged teal and shoveler, to- 
gether totalled 27.3 percent of the population. 
Nesting 
This year will be remembered for its unusually early, wet nesting 
season. Eggs found in active incubated nests were back-dated by the Gollop method 
to determine approximate date of laying. By applying an assumed figure of one day 
per egg of the clutch, the approximate date of nest initiation was determined. The 
earliest pintail nest so calculated was April 21, and for mallard, April 19. First 
nesting attempts, as determined by amount of down present in the incubated nests, 
peaked during the week of April 24-30 for pintails, and the week of May 1-7 for 
mallards. 
Only nests active when found were used in determining percent hatch- 
ing success. Of these 153 nests of nine species, 72 or 47.4 percent produced 
ducklings. An even 50 percent of the 50 pintail nests hatched successfully, while 
48.8 percent of 80 mallard nests were successful. Since these figures include 
data from all nesting attempts, nests were then reclassified as being either first 
attempts or renesting attempts, according to the amount of down present in the 
incubated nest. These corrected data indicate a 64.9 percent hatch for pintail first 
attempts and a 61.8 percent hatch for mallard first attempts. Biggest cause of nest 
