141 
WATERFOWL BREEDING GROUND SURVEY IN CALIFORNIA 
John E. Chattin, A. W. Miller and A. E. Naylor * 
Introduction 
The major waterfowl producing areas of the State have been covered by 
the breeding ground.survey each year for the past four years. By way of review 
it should be noted that at present 75 percent or more of California's production 
comes from two areas, the northeastern or "Great Basin" part of the State and the 
rice growing section of the Sacramento Valley. The northeastern region, which 
includes the Lower Klamath and Tule Lake Basins, contains over 100 lakes, natural 
marshes, and artificial water impoundments on which over one-third of the ducks in 
the State are raised. The scattered distribution of water areas within this great 
basin type makes it impossible to fly aerial transects. As.a result this entire area 
was given complete aerial coverage of all water and marsh areas to determine total 
numbers of breeding waterfowl. 
The second important waterfowl production area in the State is the valley 
of the Sacramento River. Under present conditions the Sacramento Valley serves 
to produce one-third of the State reared waterfowl. The bulk of this area is devoted 
to intensive agriculture with only a remnant of the once vast marshlands remaining. 
These remaining marsh and overflow lands are largely in private ownership and are 
controlled primarily by private duck clubs. Coupled with these remnants of marsh- 
lands the culture of rice as a commercial crop is responsible for a large proportion 
of the waterfowl raised in this area. From late April through the middle of September, 
over 200,000 acres of shallow stabilized water in the form of contoured rice fields are 
available to nesting ducks. Before the rice becomes too high, this area can be ideally 
covered by aerial transect flights. Later in the season, however, brood counting and 
fall population counts are difficult to accomplish due to the dense cover growth and 
inaccessible nature of these areas on foot. In contrast to northeastern California, 
where a variety of waterfowl species nest, the primary species nesting in the 
Sacramento Valley is mallard. 
The remaining portion of the waterfowl produced in California are raised in 
scattered sections of agricultural and marsh habitat including tidal saltmarsh, stream 
channels and artificial impoundments, These areas include the Suisan marsh, 
Sacramento-San Joaquin River delta, the Grasslands in the San Joaquin Valley, etc. 
Productivity is high on these smaller areas in many cases but is limited in signifi- 
cance by the relatively small size of area and amount of water. Production surveys 
of these minor areas have been repeated this year only where time and convenience 
enabled us to do so. 
Some additional habitat was available this year in the upper San Joaquin 
Valley due to the flooding of Tulare, Buena Vista Lakes, and high water in the 
San Joaquin River channel below Mendota. , 
*Personnel of Federal Aid in Wildlife Restoration Project - California 30-R 
cooperated in this study. Credit is also due to the refuge management of Tule 
Lake National Wildlife Refuge for the gathering of the data on that area. 
