The creation of the Snake River Birds of Prey NCA was the culmination of the most intensive birds of prey research effort in history. A decade of scientific studies defined the area as critical to the future of unique bird populations, which have captured national and international attention. Basalt and rhyolite cliffs provide ledges, cracks and crevices for nesting raptors. While the adjacent shrub-grass steppe north of the Snake River, with its finely textured loess soil, provides habitat for the Piute ground squirrel and blacktail jackrabbit; major prey species for the larger raptors.

C. J. Strike Reservoir was created by the C.J. Strike Dam, which is located .75 miles west of the confluence of the Snake and Bruneau rivers. The Snake River arm of the reservoir is 24 miles in length and the Bruneau arm is 6.6 miles in length. The reservoir alternates between large open pools and narrow canyon reaches, and the canyon rims are 200-400 feet above the reservoir. Native uplands along the reservoir are covered by big sagebrush, shadscale, winterfat, greasewood, and a mix of perennial and annual grasses and forbs. There is a 300-acre marsh at the mouth of the Bruneau River, and several islands along the Snake River arm toward the upper end of the reservoir. A 13,225-acre Wildlife Management Area (WMA) borders the reservoir for much of its length.

Ornithological Summary

This site supports one of the densest populations of nesting raptors in North America. Up to 800 pairs of raptors of 12 different species nest here; Prairie Falcon, Golden Eagle, Ferruginous Hawk, Northern Harrier, Great-horned Owl, Long-eared Owl, Red-tailed Hawk, Swainson?s Hawk, American Kestrel, Burrowing Owl, Short-eared Owl, and Western Screech-owl. More than 200 Prairie Falcons nest here, representing up to 5% of the world?s population of this species. Bald Eagles winter here, and Long-billed Curlews are common breeders.

Two hundred forty species of birds are known to use the C. J. Strike area annually. Of which, 98 breed in the area, and 105 species commonly winter. Large numbers of passerines pass through this area during the spring migration, (John Doremus counted 125,000 swallows of five species, in four hours moving through the area), although no one has attempted to count the number of birds using this area as a migratory route. Birds are funneled into the area from a 125-mile wide front at the Idaho/Nevada border. The WMA is an important feeding area for passerines after they have crossed the Nevada desert. The reservoir is a nursery for several hundred Western and Clark?s Grebes. A count, in early July 1990, found 485 Clark?s and 437 Western Grebes on the reservoir from the Bruneau arm to Loveridge Bridge on the Snake River arm. In 1983 John Doremus counted 112 pairs of grebes of both species, with young, in one pool on the Snake River arm. Long-billed Curlews, Western Screech-Owls, Northern Saw-whet Owls, and Burrowing Owls breed in the area, and American White Pelicans (50-300 individuals) can often be send during the summer. Because this valley is warmer than the surrounding area many half-hardys like American White Pelicans, Double-crested Cormorants, Yellow-rumped Warblers, and Loggerhead Shrikes successfully winter here. Trumpeter Swans and Tundra Swans use the area during migration and winter. There is always a small population of Merlins, [Northern] Goshawks, and Ferruginous Hawks during the winter. Reservoir: During Spring and Summer, waterbirds (Virginia Rail, Sora, American Avocet, Black-necked Stilt, Great Blue Heron, Caspian Tern, Forster?s Tern, California Gull, Ring-billed Gull, Double-crested Cormorant) and waterfowl common. Large numbers (approx. 100,000) of migrating and wintering waterfowl (Mallard, Canada Goose, Trumpeter and Tundra Swans, etc.). Ted Trueblood: Attracts thousands of waterfowl (Tundra Swan, Canada Goose, Greater White-fronted Goose, Snow Goose, Wood Duck, Mallard, Gadwall, N. Pintail, American Wigeon, N. Shoveler, Cinnamon Teal, Blue-winged Teal, Green-winged Teal, Redhead, Ring-necked Duck, Greater Scaup, Lesser Scaup, Common Goldeneye, Bufflehead, Hooded Merganser, Ruddy Duck), waterbirds (Horned Grebe, Eared Grebe, Pied-billed Grebe, Western Grebe, Clark's Grebe, American White Pelican, Double-crested Cormorant, Great Blue Heron, Great Egret, Black-crowned Night Heron, White-faced Ibis, California Gull, Ring-billed Gull, Franklin?s Gull, Herring Gull, Caspian Tern, Forster?s Tern, Black Tern), and shorebirds (Greater Yellowlegs, Lesser Yellowlegs, Dunlin, Least Sandpiper, Long-billed Dowitcher, Common Snipe, Wilson's Phalarope, Long-billed Curlew, Dunlin, Solitary Sandpiper, Baird?s Sandpiper, Pectoral Sandpiper) during migration and summer. Breeding area for American Avocet, Black-necked Stilt, Wilson?s Snipe, and Killdeer. Yellow-headed and Red-winged Blackbirds are abundant, Soras and Virginia Rails are heard occasionally, and Northern Harriers are common. Wintering species include Tundra Swans and waterfowl.

Conservation Issues

Invasion of highly flammable non-native annual weeds, particularly cheatgrass, are a serious, and rapidly spreading, problem on the NCA. These plants provide fine fuels that perpetuate recurring fires and eliminate native shrub communities. Destruction of the desert crust is a major threat, which is exacerbated by over-grazing and recreational overuse, particularly by off-road vehicles. Similarly, these activities are also increasing localized problems of soil erosion and degradation. To help curb the spread of noxious weeds, increasing fires, and impacts on soil, off-road vehicle use is being controlled to some extent. In addition, fire-disturbed sites are being reseeded with fire-tolerant species. Illegal shooting of raptors and disturbance at nest sites in localized areas is a problem. To limit this problem, a partial shooting closure has been implemented. There is also a potential decrease in ground squirrel and badger populations, both of which are highly important to raptor populations. To educate the public about the area and the conservation problems, educational signing has been added, a visitor area has been developed, and maps and educational brochures for the public have been prepared. To deal with NCA-wide issues, a Park Ranger has been hired, a management plan for the NCA has been developed, and there is management and monitoring of livestock use and U.S. National Guard training area use.

Degradation of water quality from an increased nutrient load from agriculture and food processing is a major problem at this site. To combat this, it has been proposed to strictly enforce water quality standards for agriculture and industry. Because habitat degradation from excessive grazing is also a problem, grazing is now only used to improve wildlife habitat on managed lands. There is a concern about pesticide poisoning for wildlife in the area. Pesticide applicators are being trained and licensed by the state to reduce this impact as much as possible. Invasion by exotic plants is also a significant problem, which has led to the current efforts to use physical, biological, and chemical controls. Recreational development and overuse is also a problem at this site.

Ownership

Idaho Power Company, Idaho Dept. Fish and Game, and BLM

Habitat

Snake River plain topography, flat to gently rolling; snake River canyon surrounded by basalt cliffs. Climate is hot in summer (up to 105°F) and cold in winter (down to -20°F). It?s in an 8-10 inch precipitation zone (cold desert), with soils that are mainly wind-blown loess. Geology is largely volcanic ? parent rock basalt or rhyolite. Plant communities consist of Wyoming big sagebrush associated with Thurber needlegrass, Bluebunch wheatgrass, Bottlebrush Squirreltail, Basin wildrye, Indian ricegrass, Sandberg bluegrass, or needleandthread grass. Major shrubs in salt desert shrub communities include winterfat, shadscale, bucksage, spiny hopsage, greasewood, or Fourwing or Nuttall Salthbush.The C. J. Strike Reservoir is found in the Upper Sonoran life zone. The climate is strongly influenced by the precipitation shadow of the Oregon Coast Range and the Cascade Mountains, such that annual precipitation is less than eight inches. Summers are hot and dry and winters are generally mild. A Potamogeton is the common submergent vegetation in the Snake River arm of this site. Emergent vegetation is mainly hardstemmed bulrush, cattails, and sedges. The riparian zone is dominated by shrubs, forbs and grasses with an overstory of willows and Russian olive. The uplands are dominated by black greasewood, shadscale, and big sagebrush with an understory of annual and perennial grasses. Where the uplands have burned they are dominated by annual grasses, especially non-native cheat grass. There are planted tree lines of Russian olives and locust and some grass fields are being dominated by ?volunteer? Russian olives. Common agricultural crops in the area are corn, alfalfa, small grains, irrigated pasture, and sugar beets.

Land Use

C. J. Strike Dam was built to produce electricity. It is used to meet peak electrical demands throughout the day. The dam increased the acreage of land under irrigated agriculture and reduced the cost of irrigation by allowing water to be gravity fed into canals. Before the dam was built irrigators had to pump water from the river. Those irrigators that pump from the reservoir have to lift water a shorter distance, reducing the cost of irrigation. The area is also a popular camping and recreation area for people from southwestern Idaho and northeastern Nevada. There is a commercial resort at the reservoir edge and the Mountain Home Air Force Base has a recreational site on the reservoir. This reservoir is a popular cold and warm water fishery and waterfowl and upland game bird hunting area. Other recreational pursuits are boating, water skiing, sailing, and bird watching.

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