Habitat & Wildlife

Waterfowl rest in the shallow water between wetland grasses as others fly overhead with sunlit desert mountains in the background.

With over 90 percent of California’s original wetlands gone, the Salton Sea has become one of the most important nesting sites and stopovers along the Pacific Flyway. In some years, as many as 95 percent of the North American population of eared grebes may use the Sea, 90 percent of American white pelicans, 50 percent of ruddy ducks and 40 percent of Yuma Ridgeway's rails. With its marine, freshwater, desert, wetland and agricultural habitats, the Sonny Bono Salton Sea National Wildlife Refuge provides habitat for hundreds of birds and wetland species, including several that have been listed as endangered or sensitive by the U.S. Fish and Wildlife Service.


Refuge Habitats

Wetlands

A bird wades in brown water behind a screen of green and tan grasses.

 

As of 2020, the Sonny Bono Salton Sea NWR has 826 acres of manageable wetland units for resident and migratory bird species. Some specified impoundments are managed as permanent wetlands to provide critical nesting and year-round habitat for the endangered Yuma Ridgeway’s rail, while others are geared towards the propagation of plants favorable for food and cover through periodic flash flooding in the spring and summer months.

All wetlands are flooded from water supplied by the Imperial Irrigation District. This water is termed “class 1” irrigation water, which is free of fertilizers, toxic pesticides and high levels of salts that are common in agricultural drain water. Salt cedar (Tamarix pentandra) and sesbania (Sesbania exalta) are problem weed species that often accompany moist soil management on the refuge.  

Croplands

A green tractor pulling discs turns over the dry soil in a field of brown grass.

The refuge implements an intensive farming program to provide suitable forage for over 30,000 wintering geese and other migratory birds and wildlife. Croplands comprise of 869 acres on the refuge, with many fields cooperatively farmed by local farmers. Crops planted on refuge land includes alfalfa, wheat, rye grass, milo, millet, and Sudan grass. 

Tree Rows

Rows of low, green trees with wide spreading branches extend into the distance under a clear, blue sky.

Refuge tree rows managed for native species and biodiversity fall into this category. Species planted include honey mesquite, screwbean mesquite, blue palo verde, Mexican palo verde, fairy duster, sweet acacia, catclaw acacia, and desert ironwood. 

Refuge Wildlife

Since its’ establishment in 1930, the refuge has become a safe haven for a diverse assortment of wildlife. Yet the Salton Sea has changed over the years with its increasing salinity and decreasing water levels. Up until 1960, enthralling species like the wood stork and roseate spoonbill could be seen in the hundreds foraging along and near the shoreline and roosting on tree snags. The refuge has documented over 519 different species of wildlife. Of those, at least 433 are birds, 41 are mammals, 22 are reptiles and amphibians, and 15 are fish. While most of the birds within the refuge are migratory, an estimated 109 are year round residents.

In addition to the categories below, the Sea is also inhabited by a large number of barnacles and Corixidae.

Mammals

A bobcat, with black stripes on its yellow-orange fur, sits in a tree and patiently awaits its prey.

Common species of mammals found on the refuge include: desert cottontail, Merriam's kangaroo rat, muskrat, raccoon, valley pocket gopher, striped skunk, coyote, bobcat, round-tailed ground squirrel, desert pocket mouse and various bat species.

Visibility varies greatly from species to species due to the nocturnal habits of some and seasonal hibernation of others. Most rodent species exist in terrestrial habitats. During winter months, rodents provide food for heron and egret species as well. Muskrats are present in freshwater drains and ponds where their feeding and burrowing activities help maintain marsh habitats for various other wildlife species.  

Birds

 A flock of black skimmers, slender black birds with large, orange bills, fly low over still water.

The Salton Sea has been designated as an internationally important staging area for shorebirds. Over 124,000 shorebirds of at least 25 species migrate through the Salton Sea along the Pacific Flyway. It is considered the third most important shorebird habitat west of the Rocky Mountains. Several species rely heavily on the Salton Sea to support a large portion of their flyway population including: western sandpipers, willet, least sandpipers, American avocet, dowitcher spp., red-necked phalarope, whimbrel, and black-necked stilt.

Depending on the season, other common birds to find on the refuge include: California brown pelican, American white pelican, black skimmer, mountain plover, eared grebe, ruddy duck, yellow-footed gull, northern shoveler, Ross’s goose, snow goose, Gamble’s quail, roadrunner, cattle egret, white-faced ibis, American kestrel, marsh wren, sandhill crane and hundreds more.

Bird species of concern on the refuge include:  

  • Yuma Ridgeway's rail (Rallus obsoletus): Listed by the IUCN as Near Threatened.
  • Burrowing owl (Athene cunicularia): Species of concern in California. Due to their large range and population size, they are listed by IUCN as Least Concern, though the population trend appears to be decreasing. More than 70 percent of the California population is found within the Imperial Valley.
  • Gull billed tern (Gelochelidon nilotica): Designated as a Bird of Conservation Concern.
  • Mountain plover (Charadrius montanus): Listed by IUCN as a near threatened species.
  • Western snowy plover (Charadrius nivosus): Listed by IUCN as near threatened. The Salton Sea supports the greatest number of western snowy plovers in the interior of California.

Amphibians

Due to environmental factors, amphibians are not found in large numbers or diversity at the Sonny Bono Salton Sea NWR. Species occurring on the refuge include bullfrogs (Rana catesbeiana) and lowland leopard frogs (Rana yavapaiensis). Woodhouse’s toad (Bufo woodhousii) and red-spotted toads (Bufo punctatus) are also found on the refuge.

Reptiles

 A desert spiny lizard, with a reddish head and yellow-and-black speckled back, climbs out of its hiding place.

Many different reptiles call the refuge home. Common species include the gopher snake (Pituophis catenifer), western diamondback (Crotalus atrox), coachwhip (Masticophis flagellum), common kingsnake (Lampropeltis getula), whiptail lizard (Cnemidophorus sp.), desert spiny lizard (Sceloporus magister) and side-blotched lizard (Uta stansburiana). The spiny soft-shell turtle (Trionyx spiniferus) and the desert tortoise (Gopherus agassizii) are also found on the refuge. Spiny soft-shell turtles are found in freshwater drains and ponds, while the desert tortoise, although rarely seen, can be found in the upland desert areas.

Fish

Fish were initially brought into the lake with the water that originated from the Colorado River and included native species, such as carp, rainbow trout, striped mullet, humpback sucker, and desert pupfish. As early as the 1930s, native fish had begun to die off because they couldn’t tolerate the high salinity. Periodically, decomposition of large algal blooms diminishes the dissolved oxygen in the water. This decomposition has been tied to occasional fish die-offs that occur throughout the year. Tilapia are among recent fish to be stocked in the sea, but with a growing salt content, even they are becoming scarce.

 

The endangered Desert pupfish (Cyprinodon macularius), while present in the Sea, is rarely seen. The desert pupfish was listed as endangered by the U.S. Fish and Wildlife Service on March 31, 1986.