142 
Scope and Methods 
saith fer Saat ar eee 
Fundamentally the survey consists of an aerial census of the pairs of ducks 
present on the breeding grounds during the last half of May and the first half of June, 
assuming an even sex ratio. Production is based on the number of pairs found, the 
relative nesting success, and the average brood size on each area. The latter two 
factors require considerable ground work and it is not always possible to conduct 
such surveys on each unit every year. An attempt is made to keep the data current 
on major areas, 
Goose production in California is confined to the northeastern section and 
involves only Canada geese. By June 1 when the survey is made in this region, the 
nesting season is over for this species and most of the birds are more than half 
grown. The total number of old and young is counted and this figure is used for the 
total fall population. This year special attention was given the breeding population 
of Sandhill Cranes in California and the results are appended to this report, although 
no comparative data are available. Insofar as possible the areas covered, census 
routes traveled and methods employed have been duplicated from the pattern estab- 
lished last year. Essentially the same observers have been used in each area as 
were used in previous years. 
All of the aerial transects were flown at elevations of 150 feet at speeds of 
85 to 90 miles per hour with two observers covering a ground strip 1/8-mile wide 
on either side of the airplane. Under these conditions experienced observers can 
accurately record species and sex of those ducks exhibiting divergent sex character- 
istics as well as note whether the birds occurred as pairs, singles, or groups of 
males where the birds are not concentrated. Where complete coverage was made, 
the reservoir or marsh was circled or traversed at about the same elevation and 
speed until the observers were satisfied that the majority of the ducks had been seen. 
It was often possible to get some brood counts at the same time on geese. The 
airplane used was a Fairchild 24, which is a four-place plane with a high wing. 
Over 60 hours of flying time was used. 
Weather and Water Conditions 
California generally experienced one of the heaviest precipitation years on 
record. The winter was reasonably mild at lower elevations and the heavy snow pack 
in the high country provided a good water supply. The wintering birds had ample food 
and left for the breeding grounds in good condition. The spring runoff was great 
enough to cover many areas which have not been flooded since 1937-38. These 
furnished additional nesting areas. Conditions were considered nearly ideal over 
most of the State. 
Results 
For the following areas comparable data have been gathered in all four 
years. A standard pattern of reporting has been used to include pertinent facts with 
reference to individual areas. On a sampling basis, coverage of the entire State 
production can be considered as essentially complete; thus figures are shown as 
actual numerical estimates of total numbers rather than as ducks per square mile. 
Data on individual areas studied are summarized as follows with such remarks as 
are pertinent. 'Total fall population" includes resident adults plus locally reared 
young. 
