173 
Northeast Colorado 
As in preceding years, the approach in northeast Colorado was both 
intensive and extensive. Ona sample township (T7N, R68W) in the Cache la Poudre 
Valley, all waterfowl habitats were covered by foot at bi-weekly intervals during 
the breeding season and a good estimate of total production determined. The South 
Platte Valley was studied extensively, wherein an aerial trend route was covered 
three times during the season. 
The information collected in 1952 for these breeding areas is presented 
in Tables II to VII, inclusive, 
Cache la Poudre Valley - A comparison of the total territories on the Cache la 
Poudre study area in 1951 and 1952 shows that for all species there was 17.5 percent 
decrease in nesting-pair numbers this year (Table II). The percent of change given 
by species in this table is valid for only the mallard and blue -winged teal (the only 
two important ducks) because of the sample size involved. 
Table II - Waterfowl Density by Species, Cache la Poudre Valley, 1951 and 1952 
1951 1952 Percent Change 
Species Number Pairs Per Number Pairs Per 1951 to 1952 
Sq. Mile Sq. Mile 
Mallard 103 2. 86 82 2.28 - 20,4 
B-w. Teal 21 0.58 17 0.47 - 19.0 
Cinnamon Teal 1 0.03 5 0.14 + 400.0 
Gadwall 6 0.17 4 0.11 - 33.3 
Total 131 3.64 108 3.00 | - 17.5 
Examination of Table III reveals that only two types (sloughs and rivers) 
showed an increase in breeding-pair numbers in 1952. All other types decreased 
from 22 to 66 percent as compared to last year. The slough and river increase is 
believed to have been caused by the early nesting season which forced the birds to 
choose areas with residual cover such as that found on the types involved; no other 
cover was available at the beginning of the nesting season this year. 
Production figures for the study area reveal that, despite a breeding-pair 
deficiency in 1952, final production of 14 birds per square mile compares favorably 
with 13 birds in 1950 and 14 birds in 1951 (Table IV). Species composition remained 
the same, mallards being by far the most important and blue-winged teals second. 
Eight other species were observed during the three years but, even in the aggregate, 
they represent only a small fraction of the total production. The uniformity 
exhibited in total production during the three-year period is striking and probably 
significant. 
