. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. GULL EFFECT ON WATERFOWL PRODUCTION 13 the open water to safe cover is unknown. However, due to diurnal habits of gulls and the semi-nocturnal activities of ducks, tlie hazard of attacks by gulls was probably negligible during the hours of darkness. Six hundred ninety-eight eggs were laid in 77 successful duck nests for an average of eggs per nest, and 617 of these eggs hatclied for an average of eggs per nest (Table 3). Redhe
. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. GULL EFFECT ON WATERFOWL PRODUCTION 13 the open water to safe cover is unknown. However, due to diurnal habits of gulls and the semi-nocturnal activities of ducks, tlie hazard of attacks by gulls was probably negligible during the hours of darkness. Six hundred ninety-eight eggs were laid in 77 successful duck nests for an average of eggs per nest, and 617 of these eggs hatclied for an average of eggs per nest (Table 3). Redheads and ruddy ducks accounted for the majority of unhatched eggs, partly because these two species are prone to leave their nests with a partial brood before the entire clutch is hatched. The curious phenomenon of parasitism by tlie redhead occurred in 18 nests of other species. A total of 53 eggs was deposited but only 11 redhead eggs hatched. Mallards, pintails, gadwalls, cinnamon teal, widgeons, and ruddy ducks were victimized. One ruddy duck egg was found in the nest of a redhead. Most duck broods frequented the eastern portion of Ilartsou lieser- voir where they enjoyed the protection of levees and emergent vegeta- tion. Brood counts were made early in the season, but soon it became apparent that broods had a marked tendency to collect in mixed groups. This mixing of ducklings, often without regard to age or species, made further brood counting impractical (Figure 4). It was quite evident from the standpoint of numbers and species composition that numerous broods invaded ponds and ditches from the surrounding upland and meadows outside the area where nest histories had been obtained, which demonstrated the importance of these ponds as rearing places for duck broods. Widgeon and shoveler broods were much more prevalent than was indicated by the number of nests located within the studv area. 'n. s^B^ 4Kt '^*> T^Wftw 5 ^ 1' FIGURE 4. Mixed duck broods at Hartson reservoir
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