Concentrated nesting of mallards and gadwalls on Miller Lake Island, North Dakota

Harold F. Duebbert; John T. Lokemoen; David E. Sharp

doi:10.2307/3808608

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Concentrated nesting of mallards and gadwalls on Miller Lake Island, North Dakota

Harold F. Duebbert·John T. Lokemoen·David E. Sharp

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Abstract

Island-nesting mallards ( Anas platyrhynchos ) and gadwalls ( A. strepera ) were studied on a 4.5-ha island in 385-ha Miller Lake in northwestern North Dakota during 1976-80. During the 5-year study, 2,561 duck nests of 9 species were found on Island A located 180 m offshore; 59% were mallard and 34% were gadwall. In patches of shrub cover, which contained the greatest concentrations of nests, densities ranged from 241 to 389 mallard nests/ha and from 139 to 237 gadwall nests/ha. Over 97% of the nests were placed in 4 patches of shrubs totaling about 1 ha of western snowberry ( Symphoricarpos occidentalis )--Woods rose ( Rosa woodsii ) cover, which composed about 30% of the island's vegetation. Average hatching success was 85% for clutches of all species. Abandonment averaged 14% (348 of 2,426 nests) and was the major cause of egg failure. Only 15 nests (<1%) were destroyed, primarily by ring-billed ( Larus delawarensis ) or California gulls ( L. californicus ). A minimum of 15,960 ducklings including 9,300 mallards and 5,150 gadwalls hatched on 4.5-ha Island A. Hatching rates of eggs in successful nests averaged 83% for mallards and 87% for gadwalls. Despite the close spacing of nests, most individual hens maintained normal nesting regimes. Eighty-one percent of the mallard clutches contained 7-13 eggs and 81% of the gadwall clutches contained 8-14 eggs. Island A in Miller Lake provides an outstanding example of the potential for high reproduction levels of mallards and gadwalls nesting in small areas of predator-free habitats.

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Journal of Wildlife Management Article

Source-reported bounding extent: 45.935238° to 49.000687° latitude; -104.048736° to -96.554507° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeX RIS

Harold F. Duebbert, John T. Lokemoen, David E. Sharp. 1983. Concentrated nesting of mallards and gadwalls on Miller Lake Island, North Dakota. https://doi.org/10.2307/3808608

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