An investigation was made of the production rate of mallards on approx. 19,000 acres of irrigated farm land in the Sacramento Valley of Calif. Cover found on the area included rice, wheat, barley, irrigated pasture, fallow pasture, and spoilbanks. The nesting season extended from April 1 through the middle of July. The breeding population was detd. to be 400 pairs by counting territorial males along irrigation ditches. Counts obtained on 106 broods indicated an avg. brood of 4.9 ducklings during the 1st week after hatching. Brood size gradually decreased, until in the 6th week the avg. was 3.6 young. Post-breeding censuses indicated an approx. population of 2000 young and adults. Each of the original pairs therefore produced about three young ducks, for a gross production on the area of one bird per 2.8 acres of r.ice.