The Salton Sea defies description. Formed in 1905 when a break in a canal from the Colorado River filled the Salton Trough, it is arguably the most important body of water for birds in the interior of California. Those who claim the sea is totally un-natural fail to realize that it is a latter-day echo of ancient Lake Cahuilla, an even larger lake in the same spot that was the life-blood of the local Indian tribes (whose fish traps may be seen today high above the current level of the Salton Sea!). Ecologically, it may be thought of as the northern terminus of the Gulf of California, or an alternate flood plain/delta for the lower Colorado River, itself once among the most ecologically vital biomes in the Southwest. As scientists and conservationists discuss ways to save the sea by reducing salinity and preventing mass die-offs of birds, the Sea quietly waits, and rises.

Three main rivers flow into the sea, one in the north and two from the south. The Whitewater River emerges from steep, rocky slopes high in the San Bernardino Mtns. to the northwest and runs year-round nearly to the floor of the Colorado Desert north of Palm Springs. By the time it flows through the Coachella Valley, run-off from over a hundred golf courses and thousands of acres of melon and grapefruit orchards quench its thirst before it meets the warm, brownish brine of the sea, just south of the village of Mecca. In the south, the New and the Alamo Rivers flow from the Imperial Valley (see above) to form vast deltas at the southeastern end of the sea, where there are also several large islands just offshore. The shore of the sea is generally un-vegetated (the water is too salty to support much vegetation), although thickets of tamarisk grow at creek mouths and around impoundments, particularly along its southeastern shore. Politically, the sea is a mosaic of ownership that includes Indian tribal lands (northwest), an inactive DoD training range (southwest), the Sony Bono Salton Sea National Wildlife Refuge (south and southeast), Salton Sea State Park (northeast), and various private holdings.

Ornithological Summary

The avifauna of the Salton Sea has been studied for decades, and is defined by superlatives. Several bird species occur regularly here and nowhere else in western North America, contributing to the exceptionally high year-round diversity of birds here. These include one breeding species, Laughing Gull; two regular, post-breeding visitors (number vary): Wood Stork and Yellow-footed Gull; and a migrant and winter-resident shorebird, Stilt Sandpiper. The rare vanrossemii race of Gull-billed Tern breeds in the U.S. only here and at San Diego Bay. The wintering population of Eared Grebes on the Sea is the largest concentration in the world (estimates range from 0.3 to 3.5 million birds), and they are joined by thousands of Western and Clark?s grebes, likely the largest aggregation of these two species in California (Small 1994). Each summer, tens of thousands of American White Pelicans descend on the Sea, in all about 30% of the North American breeding population. Mullet Island, near the mouth of the Alamo River, hosts one of the largest breeding colonies of Double-crested Cormorants in western North America. About 40% of the U.S. population of Yuma Clapper Rail, essentially a lower Colorado River endemic, occurs in marshes at the edge of the sea (Shuford et al. 2000). The 2-300 resident Snowy Plover represent one of the largest aggregations in the interior of the U.S. (Page et al. 1991), with most of the birds concentrated along the shoreline and adjacent alkali flats in the southwest and southeast corners of the sea. The thousands of Black Terns summering (but not breeding) on the Sea may be the largest concentration in North America.

As one might predict, birds are not evenly distributed around the Sea, and patterns have been analyzed by Shuford et al. (2000). Waterfowl and shorebirds tend to concentrate primarily along the southeast shoreline (esp. the Wister Unit of the Salton Sea NWR) and secondarily in the north. Waders and their rookeries (thousands of pairs) have also been found to concentrate in the far north and in the southeast. The delta sand spits along the southeastern shore support thousands of roosting cormorants and pelicans (Brown Pelican has bred recently, and in very low numbers). Several hundred pairs of nesting gulls and terns, including Black Skimmer, are found either at the Whitewater River mouth or at Rock Hill on the southern shore. Land bird populations are strongest in remaining areas of native desert scrub or riparian habitat, including along the main rivers and creeks leading into the sea, and within the Torres Martinez Indian Reservation on the north side of the Sea.

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Conservation Issues

Along with increasing salinity, perhaps the greatest imminent, and perhaps preventable, threat to the avifauna of the Sea (D. Shuford, in litt.), Shuford et al. (In press C) also mentions disease, contaminants and human encroachment as primary conservation concerns. Spectacular die-offs caused by botulism and avian cholera have now become commonplace, with major kills being 150,000 Eared Grebes in 1992 (unknown causes), 9000 American White Pelicans in 1996 (botulism) and over 11,000 waterbirds in 1998 (cholera). These kills affect scores of other species and hundreds of individual waders, shorebirds, waterfowl, gulls and terns. Contaminants include selenium, boron and DDE, leached out of the Imperial Valley (where many of the area's birds feed) and into the Sea. Even sporadic human intrusions (e.g. fishing boats passing to close to nesting colonies) can devastate colonies in a matter of minutes as the intense summer heat cooks eggs and nestlings. For land birds, habitat clearing remains a serious threat. The few remaining populations of Crissal Thrasher, Lucy's Warbler and other native scrub-dwelling species are seeing tract after tract cleared for agriculture, particularly at the north and northwest ends of the sea. Tamarisk invasion of riparian draws (e.g. Salt Creek on the northeast side) remains a chronic threat to healthy populations of desert nesters and to freshwater marsh birds (e.g. rails).

Ownership

Politically, the sea is a mosaic of ownership that includes Indian tribal lands (northwest), an inactive DoD training range (southwest), the Sony Bono Salton Sea National Wildlife Refuge (south and southeast), Salton Sea State Park (northeast), and various private holdings.

Habitat

Three main rivers flow into the sea, one in the north and two from the south. The Whitewater River emerges from steep, rocky slopes high in the San Bernardino Mtns. to the northwest and runs year-round nearly to the floor of the Colorado Desert north of Palm Springs. By the time it flows through the Coachella Valley, run-off from over a hundred golf courses and thousands of acres of melon and grapefruit orchards quench its thirst before it meets the warm, brownish brine of the sea, just south of the village of Mecca. In the south, the New and the Alamo Rivers flow from the Imperial Valley (see above) to form vast deltas at the southeastern end of the sea, where there are also several large islands just offshore. The shore of the sea is generally un-vegetated (the water is too salty to support much vegetation), although thickets of tamarisk grow at creek mouths and around impoundments, particularly along its southeastern shore. Politically, the sea is a mosaic of ownership that includes Indian tribal lands (northwest), an inactive DoD training range (southwest), the Sony Bono Salton Sea National Wildlife Refuge (south and southeast), Salton Sea State Park (northeast), and various private holdings.