164 
Table IV. - Comparison of Ducks Observed by Aerial Count on Identical Areas 
In May 1952 and 1953 


1952 1953 
Drainage Pairs Singles* Groups Total Pairs Singles* Groups Total 
Green River 316 385 - 1,402 601 319 91 1,931 
Bear River 413 694 111 2, 325 605 332 528 2,402 
Salt River 201 699 173 1,973 369 366 270 1, 740 
Snake River 236 384 503 1,743 473 360 471 2,137 
Total 1,166 2,162 787 7,443 2,048 1,377 1, 360 8,210 
* A single was considered a mated pair in May. 
In July 1952 and 1953 



1952 1953 
Drainage Pairs Singles* Groups Young Total Pairs Singles* Groups Young Total 
Bear River 30 314 1,165 780 2,319 4 10 Z2,055 69 2,142 
Salt River 15 73 71 220 394 1 25 90. 31 148 
Snake River 13 96 239 277 =6©638 4 20 83 68 179 
Total 58 483 1,475 1,277 3,351 9 55 2,228 168 2,469 
* A parent with brood was counted as a single bird in July. 
Canada Goose Breeding Pair Population and Production 

Breeding Pair Population 
The May aerial inventory covered virtually all of the goose nesting habitat within 
the State, exclusive of Yellowstone National Park. An intensive-ground survey of the 
latter area in late May explored approximately 75 percent of the total goose habitat in 
Yellowstone. The results of both aerial and ground surveys are presented in Table VII. 
It is felt the total of 1,900 represents the number of geese in Wyoming in May, 1953. 
Of these 1,211 were found on Western Slope and Great Basin drainages, an increase of 
nearly 15 percent over 1952. 
A thorough discussion of the hazards involved in considering a resident spring 
population of geese, particularly paired birds, as an actual breeding population has been 
given in the report on experimental studies designed to improve the status of the Canada 
goose populations throughout the State (Project W-50-R-2, Work Plan 1, Job No. 6). 
Briefly summarized, this discussion concludes that only the single geese observed in 
May represent the actual number of breeding pairs. On this hypothesis, breeding singles 
in Table VII have been adjusted upward from 251 to 335 on basis of a 25 percent nest 
mortality at the time of the May inventory. . 
7” 
Goose Production 
Utilizing the number of breeding singles observed in May (251) multiplied by the 
average brood size obtained in July (4.2), a tentative production figure of 1,054 geese 
was derived. It was assumed that nest destruction, desertion, egg infertility and 
juvenile mortality following the time of the May inventory would compensate for 
undetected nesting geese. 
