166 

The remainder of the waterfowl produced in California are raised in scattered 
sections of agricultural and marsh habitat including tidal saltmarshes, stream 
channels, and artificial impoundments. These areas include the Suisun marsh, 
Sacramento-San Joaquin river delta, the Grasslands of the San Joaquin valley and the 
North Bay. In many cases, production is high on these areas, but is limited in 
significance by the relatively small size of the area and the amount of water. A 
nesting survey was carried on in the Grasslands. 
Weather and Water Conditions 
The winter was relatively mild and the spring migration began the latter part 
of February. Most of the Pintail and geese left the Valley by the middle of March 
or the first of April. However, Lesser Canada geese and some cacklers and white- 
fronted geese did not leave Northeastern California until after the first of May. 
Canada geese began nesting early in Marsh and the first broods were seen April 2 
at the Tule Lake National Wildlife Refuge. Although winter precipitation was con- 
siderably lighter than the previous three years, it was still near normal in most 
repions of the State. 
Scope and Methods 
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. 
- 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. Since the goose nesting season is over when the regular 
survey flights are made in June, a special survey was made in early May to record 
the number of breeding pairs. The June survey was then used to determine production 
and fall populations. 
Insofar as possible the areas covered, census routes traveled, and methods 
employed have been duplicated from the pattern established in previous years. Census 
flights were made with a pilot and two observers. On some flights a different 
observer was used than in previous years, but in all cases at least one of the observers 
had flown the census route before, 
All of the aerial transects were flown at elevations of 150 feet at speeds of 
85 to 90 miles per hour with the 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 
characteristics as well as note whether the birds occured as pairs, singles, or 
groups of males. 
