Evaluation of management practices in wet meadow habitats at Grays Lake National Wildlife Refuge, Idaho, 1997-2000.

Authors(s): J. E. Austin, W. H. Pyle, J. R. keough and D. H. Johnson

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Publication Date: 0000-00-00

Type: Final report to U.S. Fish and Wildlife Service-Region 1.

Location: Jamestown ND

Abstract: We assessed the relative values of 4 management practices (idle, late season grazing, fall prescribed burning, and rotation of idle and summer grazing) to biotic resources of the grassland-wetland meadow ecosystem at Grays Lake during 1997-2000. Three replicates of each treatment were randomly assigned to 12 experimental units that bordered the deep emergent marsh. Biotic factors examined included the breeding bird community and abundance, nesting activity and nest success, small mammal abundance, plant community, and annual plant biomass production. Fall burns achieved treatment objectives, removing most residual vegetation across a range of cover types. Objectives for grazing treatments were mostly attained; however, vegetation use levels were insufficient for consistent attainment of treatment objectives. Savannah sparrow, American coot, Canada goose, sandhill crane, mallard, and yellow-headed blackbird were the most common bird species present. Densities of 2 bird species (savannah sparrow and red-winged blackbird) were related to year effect only. The effect of unit on densities of redhead, lesser scaup, ruddy duck, sora, long-billed curlew, and common snipe likely reflects habitat differences among units. Densities of 6 species (eared grebe, canvasback, American coot, American avocet, willet, and common yellowthroat) were related to both year and unit effects. Treatment affected densities of 6 of the 29 species examined (mallard, northern shoveler, cinnamon teal, blue-winged teal, American crow, and yellow-headed blackbird); we found no common trend in response to treatments among those species. Overall, idled habitat did not stand out to be a valuable treatment, whereas grazing tended to have positive responses for a number of species. Burning was more likely to result in reduced bird densities than other treatments. We also describe the distribution of species observations among 8 different habitat types. Of the 23 nesting species sampled in the experimental units, the most common were American coot, sandhill crane, Canada goose, American avocet, mallard, and cinnamon teal. Daily survival rates (DSRs) of dabbling duck nests (all species pooled) were negatively affected by fall grazing. We detected no effects of treatments on DSRs of Canada geese or sandhill crane nests. DSRs for sandhill crane nests were higher in 1998 than in 1999 or 2000 and were slightly higher than that in 1997. DSRs for coot nests were affected by both year and treatment; within-treatment differences among years were extensive. In 1998, when all units were idled, DSRs for coot nests were higher in units assigned to idle treatment than those assigned to fall-grazed or rotation treatment. DSRs for coot nests did not differ among treatment blocks in 1997 (all units idled) or 1999 (first year after treatments). We speculate that compaction of residual vegetation by snowpack reduced any differences between idle and treated units and thus lessened the value of idle habitat for most nesting birds. Nesting densities and nest success rates of Canada geese, dabbling ducks, and sandhill cranes were lower those that reported from Steel's (1952) study in 1949-1950, but differences in habitats and areas searched relative to our study make comparisons difficult. Nest success rates of sandhill cranes also were lower than those reported by Drewien (1973). Declines in nest success probably are related to changes in predator community. We captured 5 species of small mammals (meadow vole, montane vole, deer mouse, vagrant shrew, and ermine). Populations of meadow and montane voles irrupted in 1998 then crashed in spring 1999; the most marked changes were in montane vole numbers. Capture rates of ermine and observation rates for striped skunks and raptors suggested a numerical response (higher recruitment) by these predators to higher prey abundance and possibly distributional shifts (movement into areas of more abundant microtines). We did not detect differences in capture rates among treatments for any species, but captures rates were relatively low in post-treatment years. We found little evidence to indicate that litter or vegetation affected capture rates, but sample sizes were limited. Predator observations during field activities detected the presence of 20 predator species. The most commonly observed predators were buteos, corvids, northern harrier, eagles, falcons, striped skunk, and red fox. Seasonal variation in raptor species reflects migrational movements through the area in spring and fall. Mapping of mammalian predator observations indicated seasonal and annual variations in their activity patterns in the basin and on the experimental units. We noted high levels of fox and skunk activity in the southeast portion of the basin, an area also heavily used by nesting waterbirds. The lakeshore habitats at Grays Lake support an abundance of breeding birds, particularly savannah sparrows, coots, Canada geese, mallards, sandhill cranes, avocets, and yellow-headed blackbirds. The lakeshore habitats also are important for foraging by marsh-nesting species such as white-faced ibis and Franklin's gulls. Strategies that increase habitat quality for foraging and nesting/brood-rearing habitat for these species would yield the greatest benefit to the regional bird community and populations. Conversely, abundance and production of dabbling ducks as a group were relatively low in the lakeshore area, suggesting that the lakeshore habitat probably does not provide a significant contribution to the regional population. The materials included here provide the necessary framework for continuing monitoring of key biotic resources in the lakeshore habitat of Grays Lake National Wildlife Refuge. This 4-year study should be viewed as the first step in a long-term study to fully address effects of management practices in a montane wetland environment.

Keywords: Gray's Lake, Idaho, National Wildlife Refuge, management, breeding, bird, ornithology, nest, nesting, habitat, population, mortality, mammal, fire, grazing, livestock, animal, perching , bird, Aves, Savannah sparrow, Passerculus sandwichensis, sparrow, Emberizidae, Passiformes, passerine , coot, American coot, Fulica americana, goose, Canada goose, Anatidae, Branta canadensis, avocet, Recurvirostra americana, crane, sandhill crane, Grus canadensis, mallard, Anas platyrhynchos, waterfowl, water bird, yellow-headed blackbird, Xanthocephalus xanthocephalus, red-winged blackbird, Agelaius phoeniceus, lesser scaup, Aythya affinis, ruddy duck, Oxyura jamaicensis, sora, Porzana carolina, long-billed curlew, Numenius americanus, common snipe, Gallinago gallinago, eared grebe, Podiceps nigricollis, canvasback, Aythya valisineria, American avocet, willet, Catoptrophorus semipalmatus, common yellowthroat, Geothlypis trichas, northern shoveler, Anas clypeata, cinnamon teal, Anas cyanoptera, blue-winged teal, Anas discors, American crow, Corvus brachyrhynchos, dabbling duck, Anas, mammal, rodent, meadow vole, Microtus pennsylvanicus, vole, Muridae, Cricetidae, montane vole, Microtus montanus, mouse, deer mouse, Peromyscus maniculatus, vagrant shrew, Sorex vagrans, Soricidae, insectivore, shrew, ermine, Mustela erminea, stoat, Mustelidae, skunk, striped skunk, Mephetis mephitis, raptor, Buteo, Corvidae, northern harrier, Circus cyaneus, eagle, fox, canine, red fox, Vulpes vulpes, accipter, falcon, peregrine falcon, Falco peregrinus, migration, white-faced ibis, Plegadis chihi, Franklin's gull, Larus pipixcan, gull