. Bulletin of the Department of Agriculture. Agriculture; Agriculture. WILD DUCKS OF THE BEAK RIVER MARSHES, UTAH. Species. Redhead Cinnamon teal Mallard Shoveler, or spoonbill Gadwall Ruddy duck Pintail Estimated number of breeding pairs. 1,725 800 300 250 200 175 130. Green-winged teai Widgeon Blue-winged teal Scaup duck, or bluebill. Total 3,650 1 Not included in total. As a conservative estimate each pair of clucks may be expected to rear 5 young, and as the average brood varies from 7 to 12 indi- viduals this allows for considerable mortality among ducklings. Adding the survivors to
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. WILD DUCKS OF THE BEAK RIVER MARSHES, UTAH. Species. Redhead Cinnamon teal Mallard Shoveler, or spoonbill Gadwall Ruddy duck Pintail Estimated number of breeding pairs. 1,725 800 300 250 200 175 130. Green-winged teai Widgeon Blue-winged teal Scaup duck, or bluebill. Total 3,650 1 Not included in total. As a conservative estimate each pair of clucks may be expected to rear 5 young, and as the average brood varies from 7 to 12 indi- viduals this allows for considerable mortality among ducklings. Adding the survivors to the original pair, the total number of native birds on this marsh at the end of the breeding season should be approximately as follows: Species. Individ- uals. Species. Individ- uals. 12,075 5,600 2,100 1,750 1,400 1,225 910 350 70 70 Total 25,550 In addition to the ducks, about 100 pairs of Canada geese breed on these marshes. Allowing 3 young as the average number brought to maturity by this species, there would be a total of 500 birds at the close of the season. The nesting season for these geese is prac- tically over by May 15, and their • numbers were estimated from observations made before they disappeared in the lower marshes for their annual molt. The figures given above are approximations, but it is believed that they are not far from the truth. From them it is learned that this marsh area produces between 25,000 and 30,000 ducks in the average season, as in 1916. The question may arise as to the pro- priety, in arriving at a total, of adding the original pair of birds to the young produced. It is probable that a large part of the adult ducks that die from natural causes (as opposed to shooting) do so toward the close of the breeding season and during the molt that follows. Exhausted by the calls made upon their strength by the needs of the nesting season, they have not sufficient vitality to carry them through the annual molt that takes place as soon as they are fre
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