176 
Projected totals from the ground survey show that 1953 production for this 
area will be approximately 1,187 broods, with an average brood size of 6.7 young. 
Thus, it is estimated that 7,953 young will be produced in the irrigated portion of 
the Platte Valley this year. No comparable data are available for 1952; however, 
past studies indicate that current production is lower than usual. 
Cache la Poudre Valley 
The Cache la Poudre Valley is located directly east of the foothills in northern 
Colorado, Land use, in this area, is mainly irrigated farming; however, there are 
numerous lakes, reservoirs, and sloughs interspersed throughout the Valley proper. 
Total area of the Valley has been estimated at approximately 343 square miles of 
which 36 square miles were intensively studied by ground and air methods for a 
sample of 10.5 percent. 
Spring breeding-pair numbers for 1953 (1601) were found to be about 56 percent 
greater than 1952 (1029), (Table III). This increase was caused mainly by greater 
numbers of mallards and blue-winged teals. However, final brood counts has revealed 
that the early reported increases did not hold true for production, for final figures 
indicate a decrease of 0.5 percent from 1952 (4821 young, 1953; 4850 young, 1952). 
This slight decrease is attributed to reduced habitat caused by lower water levels in 
all cover types ultimately resulting in a definite decrease in nesting success for all 
species (46.4 percent, 1953; 75.9 percent, 1952). 
Table III. - Comparison of Waterfowl Breeding-Pairs and Production by Species, 
Cache la Poudre Valley, 1952 and 1953 

No. Production 
Species Breeding -Pairs No. Broods No. Young Per sq. mi. 
1952. 1953 1952 1953 1952 1953 1952 1953 
Mallard 781 1,181 515 543 3, 306 3,506 9.64 10.22 
B-w. teal 162 295 172 133. 1,029 829 3,00 Z.42 
Cinn. teal 48 19 - - - - - - 
Redhead - 10+ - 19 - 229 - .67 
Gadwall 38 67 - 19 - 114 - 33 
Pintail - 29 9 - 48 - 14 - 
Baldpate - - 9 - 86 - 25 - 
Ruddy duck - - 19 - 67 - 19 - 
Unidentified - - 57 29 314 143 92 42 
Total 1,029 1,601 781 743 4, 850 4,821 14,14 14.06 
Comparison of 1953 production with that of past years, as givenin Table 1V, shows 
very little difference between years. This uniformity exhibited in total production 
during the 4-year period is striking, and probably significant. In an area such as this 
which offers a variety of cover types for nesting ducks, it is possible that a saturation 
point can be reached in production. Analysis of the data indicates that there is a 
change in the nesting pattern by habitat types from year to year which seems to 
correspond to the difference in seasons, 
