Duck production at Gray?s Lake, Idaho, 1946-51

Authors(s): P. E. Steel, P. D. Dalke and E. G. Bizeau

Publication: Journal of Wildlife Management

Publisher:

Publication Date: 0000-00-00

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Location:

Abstract: Waterfowl production at Grays Lake was examined during April-October, 1949-1951. The waterfowl breeding population was estimated at 15,000 ducks in 1949, 12,000 in 1950, and 10,000 in 1951. Breeding ducks include mallards (Anas platyrhychos), northern pintails (Anas acuta), cinnamon teal (Anas cyanoptera), blue-winged teal (Anas discors), gadwall (Anas strepera), northern shovelers (Anas clypeata), green-winged teal (Anas discors), canvasbacks (Aythya valisineria), redheads (Aythya americana), lesser scaup (Aythya affinis), and ruddy ducks (Oxyura jamaicensis). Mallards and pintails comprised approximately 50% of dabbling ducks, and canvasback and redheads were the predominated diving ducks present. Apparent nest success of all species averaged 70% during this 3-year study. For each species, distribution of nests among habitats, apparent nest success rates, clutch size, egg success rates, and average brood sizes for Class I, II, and III are reported. Over 60% of the nests were found in the southeastern portion of the Grays Lake basin. Bulrush and cattail were most important for diving ducks but also held 37% of mallard nests; 97% of all duck nests in all marsh habitats were within 15 yards of the nearest open water. Nests of dabbling ducks were most commonly found on islands, along the lakeshore, and in upland fields. Nest losses were attributed to mammalian predators (29%), avian predators (22%), grazing (3%), unknown predator (7%), and desertion (28%). Overall duck production was estimated as 47 nests/100 habitat acres in 1949, to 39 nests in 1950, to 15 nests in 1951. Waterfowl mortality due to spring muskrat trapping was estimated at 1-2%, while 14-18% of the American coot (Fulica americana) population was trapped in 1950-1951, respectively.

Keywords: Gray's Lake, Idaho, animal, breeding, bird, Aves, ornithology, population, mortality, waterfowl, water bird, Anatidae, mallard, Anas platyrhychos, northern pintail, Anas acuta, cinnamon teal , Anas cyanoptera, blue-winged teal , Anas discors, gadwall , Anas strepera, northern shoveler, Anas clypeata, green-winged teal, Anas discors, canvasback, Aythya valisineria, redhead, Aythya americana, lesser scaup , Aythya affinis, ruddy duck, Oxyura jamaicensis, nest , nesting, habitat, plant, predation, mammal, grazing, livestock, muskrat, Ondatra zibethicus, trapping, hunting, human activity, American coot, Fulica americana