Habitats of Malheur

Habitats of Malheur

“On motionless wing they emerge from the lifting mists, sweep a final arc of sky, and settle in clangorous descending spirals to their feeding grounds. A new day has begun on the crane marsh.”

― Aldo Leopold, A Sand County Almanac

  • Lacustrine

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    Malheur and Mud Lakes are best described as one of the largest inland marshes in the United States; they vary dramatically in size (from 500 to 110,000 acres), but generally fluctuate about 2 feet during the calendar year and on average cover 40,000 acres.

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  • Riverine

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    Riverine habitat on the Refuge is limited to the Blitzen River and its tributaries. Ideal riverine conditions exist when hydrologic floodplains are intact and when waterways support riparian communities that provide shade to maintain cooler water temperatures and are appropriate to stream channel type. Water turbidity is typically low with an appropriate level of sediment storage, which buffers against the sediment loading of critical rearing pools and spawning gravels for native fishes.

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  • Woody Riparian

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    The Refuge hosts a variety of woody riparian habitat along the Blitzen River and its tributaries, along ditches and canals, along remnant traces of previously active sloughs in the Blitzen Valley, and in a few patches in the Double-O Unit. Riparian habitat encompasses 800 to 1,000 acres.

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  • Semi Permanent Open Water Wetlands

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    This habitat type is best described as semi permanently flooded wetland impoundments where water depth precludes the development of extensive stands of emergent vegetation. These ares of open water provide 2,200 to 2,800 acres of important habitat in the Blitzen Valley and Double-O for waterfowl.

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  • Seasonally Flooded Marsh

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    Seasonally flooded marsh or wetlands exists within a mosaic of wet meadow and open water areas. Greater sandhill cranes and trumpeter swans depend upon this habitat type during nesting. Common emergent plant species include burreed, bulrushes, cattails, sedges, rushes, and spike rushes.

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  • Seasonally Flooded Wet Meadows

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    Meadows are influenced by water depths and the timing of irrigation. On the Refuge, they are temporarily flooded and managed artificially by irrigation. The Blitzen Valley and Double-O Unit supports approximately 20,000 to 25,000 acres of meadow habitats.

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  • Dry Meadow

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    Dry meadows are influenced by water depths and the timing of irrigation through the availability of sub-irrigation. Standing water is typically not found within these plant communities. The largest areas of dry meadow habitats are located in the northern Double-O and scattered throughout the Blitzen Valley where gradual shifts in elevation facilitate the presence of this habitat type, which lies between wet meadows and sagebrush lowland/salt desert scrub. The Blitzen Valley and Double-O currently supports approximately 4,500 to 5,500 acres of dry meadow habitats.

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  • Sagebrush Lowland

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    These upland habitats occur in elevated basin bottomlands with deep silty or sandy soils along stream channels in valley bottoms and flats. Lowland sagebrush habitat is found on 4,300 to 4,500 acres of the Refuge. Structurally, these habitats are composed of Wyoming and basin big sagebrush with an understory of perennial bunchgrasses.

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  • Sagebrush Steppe

    Sagebrush Steppe Habitat

    This community includes 14,000 to 15,000 acres on the Refuge and is dominated by shrubs with an understory of various bunchgrass and forb species found within interspaces. It can be found above greasewood/lowland sagebrush communities on various aspects, slopes, and soil types. It occurs around the fringe of the Blitzen Valley at higher elevations, at several locations in the Double-O Unit, and along the south side of Harney Lake.

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  • Salt Desert Scrub

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    Salt desert scrub occurs in barren alkali flats or alkaline valley bottomlands, and occupies 40,000 acres of the Refuge. This community is most abundant in alkaline areas around the Double-O Unit, Harney Lake, and Mud Lake, but also occurs in portions of the Blitzen Valley and along the east end of Malheur Lake where soil alkalinity is high.

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  • Dune

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    Dune habitat on the Refuge is located adjacent to playa basins and is characterized by open sand ridges with widely spaced shrubs, grasses, and forbs. Created by wind erosion off nearby dry playa bottoms (i.e., Stinking and Harney lakes), dune shrub communities are made up of shortspine horsebrush, fourwing saltbush, bud sage, green and gray rabbitbrush, and black greasewood. Grasses include Indian ricegrass, needle-and-thread, bottlebrush squirreltail, and alkali sacaton. Forbs include tufted evening primrose, Paiute suncup, Geyer’s milkvetch, sharpleaf penstemon, and various lupines. Dunes cover about 6,300 acres on the Refuge and are primarily located on the east side of Harney Lake and as islands on Malheur Lake.

    Wildlife associated with dunes are dependent on the associated vegetation and include many small mammals, including black-tailed jackrabbits, western cottontails, kangaroo rats, dusky-footed woodrats, and deer mice. Occasionally mule deer use the dunes to forage and seek cover. Shrub-steppe nesting birds such as sage thrashers, sage sparrows, and black-throated sparrows nest in the associated brush. Reptiles such as western fence lizards, side-blotched lizards, short horned lizards, and Pacific rattlesnakes frequent the dunes and some likely lay their eggs there. During high water periods, the sandy shorelines are used by foraging shorebirds.

  • Playa

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    Refuge playa habitats are located primarily in Harney Lake and the Double-O. Stinking Lake is the second-largest refuge playa and is spring-fed and isolated from other surface hydrology. Total average refuge acres of playa habitats are approximately 29,000. During low-water periods, there are large playa areas in Mud Lake and a few along the east side of Malheur Lake. These unique habitats are often intermixed with saltgrass or desert salt-scrub communities.

    Playas systems are rich in invertebrates, such as brine flies and brine shrimp. They support breeding snowy plovers and occasionally American avocets and black-necked stilts. Harney Lake is the most important breeding site for snowy plovers in the Harney Basin and has supported over 400 breeders. When these habitats develop standing water, large numbers of waterfowl have been observed using the sites. Because they are rich in invertebrates, playas attract high numbers of migrant shorebirds when they are wet. When brine shrimp are abundant, the Refuge’s playas receive high use by Wilson’s and northern phalaropes, northern shovelers, ruddy ducks, gulls, and eared grebes.