Grays Lake Ecosystem. Comparison of Wetland and Upland Management Practices at Grays Lake National Wildlife Refuge ? Breeding Birds

Authors(s): D. Johnson

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Publication Date: 0000-00-00

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Abstract: This component of the management study examines responses of the breeding bird community on the experimental units. Breeding birds use wet meadows and grasslands for courtship, feeding, and nesting, and thus their numbers and diversity may be affected by water depths, vegetation structure and species, food (seeds and invertebrates), or possible nest sites. Management treatments that affect these aspects of wet meadows and grasslands should be reflected in the breeding bird community. The objective is to determine avian responses, as measured by bird diversity and abundance, to the four wet meadow management treatments. Two surveys are conducted on foot during May and early June. Two counting methods are used to take into account differences in species ecology and mobility. Ibis, ducks, willets, phalaropes, rails, coots, swallows and passerines are counted along fixed-width line transects. Large or wide-ranging species such as including Canada geese, sandhill cranes, long-billed curlews, northern harriers, and ravens are counted on the unit as a whole, with the count performed mainly from a stationary position located where the unit is first entered; supplemental observations of those species seen on transect-based observations made during the transect census are added to the unit count. Counts are translated to pairs based on groups observed and known breeding behavior characteristics (e.g., a lone male duck is considered indicative of a pair; coots or other species where sex cannot be determined are counted and the total count divided by 2). For each species, the highest of the counts each year is used in data analyses. In 1997, we completed three breeding bird surveys during May-mid-June. No significant differences in species abundance were found among treatments, indicating units were relatively similar in pretreatment bird communities. Savannah sparrows, American coots, and mallards were most abundant of the 33 species observed. We reduced the number of surveys to 2 for remaining years. Data from 1999 and 2000 have not yet been evaluated. Species encountered during surveys include (in approximate order of abundance): Savannah sparrow, American coot, mallard, cinnamon teal, yellow-headed blackbird, gadwall, common snipe, redhead, canvasback, northern shoveler, killdeer, green-winged teal, marsh wren, common yellowthroat, eared grebe, northern pintail, lesser scaup, Wilson's phalarope, blue-winged teal, sora, western meadowlark, American wigeon, Brewer's blackbird, ruddy duck, red-winged blackbird, black tern, trumpeter swan, brown-headed cowbird, bobolink, house wren, pied-billed grebe, ring-necked duck, and Virginia rail.

Keywords: Gray's Lake, Idaho, management, breeding, habitat, animal, perching , bird , Aves, ornithology, nest, nesting, food, forage, population, mortality, ibis, duck, willet, Catoptrophorus semipalmatus, phalarope, rail, coot, swallow, passerine , Passiformes, goose, Canada goose, Branta canadensis, crane, sandhill crane, Grus canadensis, long-billed curlew, Numenius americanus, northern harrier, Circus cyaneus, raven, Corvus corax, Corvidae, Savannah sparrow, Passerculus sandwichensis, American coot, Fulica americana, mallard, Anas platyrhynchos, Anatidae, waterfowl, water bird, cinnamon teal, Anas cyanoptera, teal, yellow-headed blackbird, Xanthocephalus xanthocephalus, gadwall, Anas strepera, common snipe, Gallinago gallinago, redhead, Aytha americana, canvasback, Aythya valisineria, northern shoveler, Anas clypeata, killdeer, Charadrius vociferus, green-winged teal, Anas discors, marsh wren, Cistothorus palustris, wren, common yellowthroat, Geothlypis trichas, grebe, Podicipedidae, eared grebe, Podiceps nigricollis, northern pintail , Anas acuta, lesser scaup , Aythya affinis, Wilson's phalarope, Phalaropus tricolor, blue-winged teal, Anas discors, sora, Porzana carolina, western meadowlark, Sturnella neglecta, American wigeon, Anas americana, Brewer's blackbird, Euphagus cyanocephalus, ruddy duck, Oxyura jamaicensis, red-winged blackbird, Agelaius phoeniceus, black tern, Chlidonias niger, trumpeter swan, Olor buccinator, swan, brown-headed cowbird, Molothrus ater, bobolink, Dolichonyx oryzivorus, house wren, Troglodytes aedon, pied-billed grebe, Podilymbus podiceps, ring-necked duck, Aythya collaris, Virginia rail, Rallus limicola