Birds of the Sonoran Joint Venture
The avifauna of the Sonoran Joint Venture region is diverse, with 744 bird species breeding in, wintering in, and/or migrating through the area. This is nearly two-thirds of all bird species that occur in northern Mexico, the United States, and Canada. There are 15 endemic or near endemic species, including: Xantu's Hummingbird, Gray Thrasher, Belding's Yellowthroat, Rufous-winged Sparrow, Le Conte's Thrasher, Abert's Towhee, Thick-billed Parrot, Five-striped Sparrow, California Gnatcatcher, Black-capped Gnatcatcher, Black-vented Shearwater, Least Storm-Petrel, Yellow-footed Gull, Elegant Tern, and Craveri's Murrelet. Additionally, there are several endemic subspecies such as: Arizona Grasshopper Sparrow, Large-billed Savannah Sparrow, Sonoran Yellow Warbler, San Lucas Robin, Baird's Yellow-eyed Junco, Guadalupe Dark-eyed Junco, and Cape Pygmy-Owl. A high percentage of the world population of 20 additional species also occur here. Unfortunately, there are two species that are presumed extinct: the Guadalupe Storm-Petrel from Isla Guadalupe and the Imperial Woodpecker of the Sierra Madre Occidental.
A comprehensive national species assessment for landbirds and ducks has been conducted for the U.S. portion of the SJV. The same process will be accomplished in the Mexican portion in 2004. The process identified several landbird species that have declining population trends and/or high threats including: Bendire's Thrasher, Brewer's Sparrow, Bell's Vireo, Black-throated Sparrow, Verdin, Curve-billed Thrasher, Thick-billed Parrot, Pinyon Jay, White-throated Swift, Baird's Sparrow, and Sprague's Pipit (as determined by Partners in Flight). The SJV also has stewardship responsibility to maintain another group of birds which have their centers of abundance in or are characteristic species of our area's habitats, such as Phainopepla, Lucy's Warbler, Five-striped Sparrow, and Elf Owl.
Habitats of the Sonoran Joint Venture
The SJV covers in whole or part ten Bird Conservation Regions (BCR). Elevation in the SJV ranges from below sea level at the Salton Sea (-300'), to sea level coast line and islands, to relatively flat desert areas, to high plateaus and mountain ranges (9,900'). The climate is largely desertic with extremely low rainfall occurring in late summer, high intensity storms or low intensity, winter storms. The topography and climate produce a diversity of habitats including: desert shrublands, riparian, Madrean pine-oak, pine, mixed conifer, fir, chaparral, pinyon-juniper woodlands, desert grasslands, rock outcrops, tropical deciduous forest, desert thorn-scrub, palm groves, semi-deciduous forest, freshwater wetlands, coastal dunes, coastal shrublands, mangroves, estuarine, brackish and salt water wetlands, coastal lagoons, rocky islands, and halophytic brushlands. Of these, the desert shrublands and grasslands, Madrean pine-oak, and various coastal environments are the most unique biotas.
Birds rely on a myriad of habitats in the Sonoran Joint Venture region. In order to adequately address the conservation needs of such a broad area, we have carefully created a conservation prioritization process for each species and select priority habitats each year.Of the approximately 750 species of birds in the SJV region, 667 occur regularly. The SJV Bird Conservation Plan includes an avifaunal analysis that assesses the status and prioritizes all bird species found within the region. At a continental level, 155 species are considered Concern Species that merit conservation attention. In addition, there are 152 Regional Concern Species.