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foothill stream, moderately productive in waterfowl. The central and lower portions 
flow through semi-desert and shortgrass prairies. Its central section, downstream 
from its entry into Seminoe Reservoir, and its major tributaries ---Sweetwater, 
Medicine Bow and Laramie Rivers---constitute its most productive waterfowl area. 
Except for upstream sections of a few tributaries the lower parts of the drainage have 
limited waterfowl production. 
A generally dry spring and early summer in the Platte River drainage provided 
less waterfowl breeding habitat than was available in 1952, and continued dry weather 
into the summer caused a number of marginal nesting areas to dry up before the 
broods were on the wing. Spring run-off was late and flooding at a minimum, 
The Wind and Big Horn Rivers are two sections of the same stream, separated 
by name at about the half way point where the river emerges from the Wind River 
Canyon. In as much as the physical characteristics and use by waterfowl of the two 
halves of the stream differ, the river has been considered as two drainages for the 
purposes of this project. An important feature of the Wind River drainage is the 
Riverton Irrigation Project, which has substantially increased the amount of available 
water and has provided quantities of grain foods for waterfowl, In addition, the 
upstream portions of the River, and its tributaries -- Little Wind and Popo Agie 
Rivers -- provide supplementary nesting habitat. 
The Big Horn River drainage, largely as a result of the length of its tributaries 
ani their productivity in the upper reaches, supports a moderate nesting population, 
The River offers limited breeding habitat, and can be closely compared to downstream 
portions of the Green River. Although the upper sections of the tributaries flow through 
mountainous and foothill country, the drainage is primarily a semi-desert region. 
Irrigation projects adjacent to the Shoshone and Greybull Rivers are of more importance 
to waterfowl in winter than during the breeding season. 
Both the Wind and Big Horn drainages were characterized in early spring by much 
the same weather and water conditions as experienced west of the Continental Divide. 
Following a late spring period of low temperatures and stormy weather, however, this 
repion had very little moisture. 
The northeast quarter of Wyoming can be classified as a stockpond region. Four 
Rivers, the Tongue, Powder, Belle Fourche, and Cheyenne drain this area, but in 
themselves are of little importance to breeding waterfowl. It is reported that in wet 
years this stockpond country is an important duck producing region. In 1953 this area 
was of little value to waterfowl due to dry, spring weather. Rains in late June and July 
filled many of the reservoirs, but came too late to be of much benefit to the ducks. 
Duck Breeding Pair Population and Production 
Breeding Pair Population 
Table I summarizes by drainages the total number of breeding ducks observed 
in the aerial census between May 1 and 14, 1953. Survey personnel were impressed 
this spring by the comparatively large number of ducks observed in groups on lakes 
and reservoirs as compared to 1952. Table IV indicates that over identical areas 
573, or 73 percent more ducks were seen in groups in May of 1953 than in 1952. A 
cold spring and uncertain weather may well have been responsible for a late, slow 
migration, resulting in an apparent increase in the breeding population in May. In 
