CENTRAL FLYWAY 
Due to circumstances beyond control it was not possible to conduct 
the annual survey in Mexico during January 1957. Although the Mexican sur- 
vey was conducted in January 1958, comparisons cannot be made between the 
two years in this important Central Flyway wintering area. On the basis of 
coverage within the United States only, there would appear to have been a 
considerable decrease in wintering populations between 1956 and 1957, and 
a compensating increase between 1957 and 1958. When the breeding population 
survey indices are used as an indicator of population trend it appears 
doubtful that the decrease recorded in 1957 took place. It appears also 
that although there has been an increase in breeding population within the 
Central Flyway this year that the increase has been small and not nearly of 
the magnitude indicated by the winter survey results. 
Throughout most of the breeding range affecting the Central Fly- 
way the season was from one to two weeks early. Much of the Flyway breed- 
ing range was characterized by drought during the 1958 season. In southern 
Saskatchewan and North Dakota the effect of the drought was apparently more 
severe than in either southern Alberta or southern Manitoba. Drought con- 
ditions prevailed also in breeding areas further north, but in northern 
habitat lack of rain can have a favorable rather than a detrimental effect. 
During June and July, general rains occurred in the Dakotas, southern 
Alberta, and southern Manitoba. These rains halted the drying trend and 
improved conditions for brood production. The first general rain in south- 
ern Saskatchewan occurred on July 12 and 13 which improved conditions some- 
what for renesters but did little to help early hatched broods. 
The July surveys revealed increases in brood production in 
southern Alberta, southern Manitoba, and South Dakota. In view of larger 
breeding populations and favorable weather conditions, increases in brood 
production are expected in Alaska and the Northwest Territories. De-: 
creases in production were recorded throughout Saskatchewan and in 
Northern Manitoba, Ontario, and North Dakota. Production was estimated 
to be about the same as last year in Wyoming, Colorado, and Minnesota. 
Overall, a summation of field reports indicates that there 
should be no change in the fall flight of ducks in the Central Flyway as 
compared to 1957. 
On the basis of an increase in the breeding population of geese, 
as measured by the 1958 winter survey, it is estimated that there will be 
a small increase in the fall flight of this group of species. 
Although there was a marked increase in the breeding population 
of coot in southern Alberta and southern Manitoba, there was a greater 
decrease in southern Saskatchewan. Also, there was a marked reduction in 
brood production in southern Saskatchewan and southern Manitoba. There- 
fore, it is concluded that there will be a moderate decrease in the fall 
flight of this species. 
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