Avian Values

Did You Know?

Nearly 510 million acres of habitat occurs within the IWJV boundary. This includes perhaps the most diverse habitat within any joint venture in the contiguous forty-eight states due to the wide variation in physiography, elevation, and climate. The following highlight the basis for the habitat diversity of the Joint Venture:

• Well over 600 mountain ranges are found within the IWJV, including 314 named ranges in Nevada alone. A total of 21 of the 33 tallest mountains in North America occur in the Joint Venture.
  
  
• Of the seven largest deserts in North America, five occur entirely within the IWJV, and portions of the other two are found here also.
  
  
• The widest extremes of temperature ever recorded in the U.S. occur in the JV, with aa range of some 200 degrees Fahrenheit between Death Valley, California and Yellowstone National Park, Wyoming.
  
  
• The change in elevation in the Joint Venture is dramatic, with a range of 14,775 feet which occurs in a distance of 90 miles in eastern California.

Of course, with such diversity comes a wide range of avian habitat niches, from alpine types to low and high elevation deserts, from world-class wetland habitat to montane wet meadows, from cedar-hemlock forests in the north to Joshua tree forests in the south, from mixed grass-mesquite types to short grass prairie, and from bristlecone pine forests to pinyon-juniper woodlands.

Unique features of Intermountain West avifawna include:

• The Intermountain West is home to 1 million breeding shorebirds and several million transients, including the majority of North America’s Snowy Plovers, American Avocets, Black-necked Stilts, and Long-billed Curlews.
  
  
• Well over 130 million acres of sagebrush-steppe habitat occurs within the Intermountain West Joint Venture, by far the largest concentration of this habitat within joint ventures.  PIF Species of Continental Importance of shrub-steppe habitat include Gunnison’s sage grouse, greater sage grouse, sage sparrow, sage thrasher, and Brewer’s sparrow.
  
  
• IWJV habitats support nearly 100% of the range of all high priority sagebrush steppe landbird species, such as: Sage Sparrow, Sage Thrasher, Sage Grouse (Greater and Gunnison’s) and Brewer’s Sparrow.
  
  
• More than half of the Pacific Flyway’s Mallard, Redhead, Canada Goose, and Rocky Mountain Trumpeter Swan Populations winter in the Intermountain West.
  
  
• More than 2 million breeding ducks nest in the Intermountain West, where some of the highest duck nesting densities found in North America occur in Colorado’s San Luis Valley and at Utah’s Great Salt Lake.
  
  
• At least 75 percent of the breeding population of eighteen bird species from PIF’s Species of Continental Importance list use Intermountain West Joint Venture habitats.
  
  
• Huge numbers of transient shorebirds, including 90% of the world’s adult Wilson’s Phalaropes, stage in Intermountain West saline-lake habitats annually.
  
  
• Goose Lake, in Oregon and California, supports one of the largest concentrations of Clark’s Grebes in North America. Mono Lake, in California, supports a Fall population of 750,000 eared grebes, more than 30 percent of the North American total.
  
  
• Three-quarters of the Pacific Flyway’s migrating birds pass through Klamath Basin annually.
  
  
• At least 80 percent of the North American population of these PIF Species of Continental Importance (Clark’s nutcracker, black rosy-finch, brown-capped rosy finch, pinyon jay, Gunnison’s sage grouse, and greater sage grouse) occur exclusively year-around within the Intermountain West Joint Venture.
  
  
• In the intermountain West, at least 20 white-faced ibis colonies support 20,000 breeding birds and include the largest breeding concentrations in the world.
  
  
• Riparian habitats in the Intermountain West support the highest species diversity of any western habitat, yet it is one of the rarest of habitats here.  PIF Species of Continental Importance which breed her include black swift, rufous hummingbird, willow flycatcher, Lewis’s woodpecker, and calliope hummingbird.
  
  
• IWJV habitats support nearly 100% of the range of all high priority pinyon-juniper landbird species, such as Gray Vireo, Gray Flycatcher, Pinyon Jay, and Juniper Titmouse.
  
  
• The Great Salt Lake alone supports 130,000 nesting California gulls, while Mono Lake hosts 65,000 nesting gulls, the two largest nesting colonies of gulls in existence.
  
  
• Highly significant portions of the distribution of these upland species also occur in the Intermountain West:
  

Virginia’s Warbler, Black-throated Gray Warbler, Lazuli Bunting, Green-tailed Towhee, Williamson’s Sapsucker, Scrub Jay, Clark’s Nutcracker, Mountain Chickadee, Pygmy Nuthatch, Canyon Wren, Cactus Wren, Swainson’s Hawk, Ferruginous Hawk, Prairie Falcon, Flammulated Owl, Burrowing Owl, White-throated Swift, and Yellow-headed Blackbird.

• Low and high elevation riparian habitats are a priority throughout the IWJV area; the following species are dependent on that habitat: Calliope Hummingbird, Broad-tailed Hummingbird, Lewis’s Woodpecker, Bell’s Vireo, Black Swift, Willow Flycatcher, MacGillivray’s Warbler, American Dipper.
  
  
• Pinyon-Juniper woodlands, where more nesting-species occur in any western upland type, are characteristic of the Intermountain West.  PIF Species of Continental Importance include pinyon jay, gray vireo and gray flycatcher.