Sonny Bono Wildlife Refuge

One of Southern California’s most extraordinary birding landscapes—part wetland sanctuary, part working farm and part volcanic overlook—at the southern edge of the Salton Sea.

Photographed and researched by Mark Miller, founder of Desert Oasis Insider. Visitor information last verified July 29, 2026.

On a winter morning, the Sonny Bono Salton Sea National Wildlife Refuge can sound alive before the landscape fully comes into view. Snow geese and Ross’s geese rise from green forage fields in a rush of wings. Sandhill cranes call across the flats. Ducks gather on managed ponds, burrowing owls watch the agricultural edges, and Rock Hill stands above a mosaic of marsh, desert and open water.

Much of this habitat is deliberately maintained. Refuge staff flood seasonal ponds, protect permanent wetlands and grow winter forage with cooperating farmers. The result is one of the clearest places to understand the Salton Sea as it exists now: environmentally stressed, carefully managed and still remarkably alive.

The essentials

• The full official name is Sonny Bono Salton Sea National Wildlife Refuge. It occupies two separate management units at the southern end of the Salton Sea in Imperial Valley.

• President Herbert Hoover established the original Salton Sea Wild Life Refuge on November 25, 1930. Congress renamed it for Representative Sonny Bono on November 12, 1998; Bono did not establish the refuge.

• The federal refuge encompasses about 37,900 acres, much of it beneath the Salton Sea. More than 3,000 acres of land are actively managed for migratory birds, including farm fields, ponds, marshes and desert habitat.

• At least 519 wildlife species have been documented on the refuge and in its immediate surroundings, including at least 433 bird species. Those are cumulative records, not the number expected during one visit.

• Admission is free. Trails, observation platforms and bathrooms are open from sunrise to sunset. The visitor center is seasonal and volunteer-staffed, so its hours should be confirmed before a special trip.

Sonny Bono Salton Sea National Wildlife Refuge at a glance

Detail	Current information
Headquarters and visitor center	906 West Sinclair Road, Calipatria, CA 92233-9744
Phone	(760) 348-5278
Admission	Free
Trail hours	Sunrise to sunset
Winter visitor-center schedule	Generally Tuesday–Sunday, 8 a.m.–3:30 p.m., November–April; dependent on volunteers and closed on federal holidays
Summer visitor-center schedule	Closed approximately May/June through October; trails, platforms and bathrooms remain open
Best overall birding season	November through February
Headquarters facilities	Seasonal visitor center and bookstore, observation tower, picnic area, flush restrooms and drinking fountain
Unit 1 facilities	Hardenberger Trail, two photo blinds, observation tower and platform, kiosk and small outhouse

A refuge older than the Salton Sea resort era

The refuge began long before the Salton Sea became famous for marinas and waterfront hotels. On November 25, 1930, President Herbert Hoover signed Executive Order 5498, reserving 32,766 acres in Imperial County as a refuge and breeding ground for birds and wild animals. Its original name was the Salton Sea Wild Life Refuge.

As the Salton Sea rose, much of that original federal land went beneath the water. Additional lands along the southern shoreline became the focus of active management. Today’s approximately 37,900-acre figure includes extensive open water; only a fraction consists of the ponds, fields, marshes and uplands managed on land.

The refuge acquired its current name in 1998. Sonny Bono—the entertainer who became mayor of Palm Springs and then a United States representative—used his congressional position to draw national attention to the Salton Sea’s worsening environmental problems. After his death, the Salton Sea Reclamation Act of 1998 renamed the existing refuge in his honor. The sanctuary dates to 1930; Bono’s name was attached 68 years later.

Why farm fields belong inside a wildlife refuge

California has lost an estimated 90 to 95 percent of its original wetlands. At the same time, the Salton Sea sits on the Pacific Flyway, used by birds moving between northern breeding grounds and wintering areas extending into Mexico, Central America and South America. With fewer natural wetlands available along that route, managed habitat in Imperial Valley carries exceptional weight.

Refuge staff and cooperating farmers grow ryegrass and wheat for overwintering geese and sandhill cranes. Seasonal ponds are planted with wetland foods, flooded beginning in late summer and generally held through March. Permanent ponds provide nesting islands for terns and black skimmers, while cattail marshes support the endangered Yuma Ridgway’s rail and desert pupfish.

Reliable forage inside the refuge also helps reduce goose damage to neighboring commercial farms. Conservation here is not a fence around untouched nature; it is the continual management of water, crops and habitat across a working agricultural landscape.

More than 400 bird species—and no single “typical” day

The U.S. Fish and Wildlife Service wildlife inventory documents at least 433 bird species in the refuge and nearby area. The larger inventory includes at least 519 species across birds, mammals, reptiles, amphibians and fish.

The bird list is the headline. American white pelicans, eared grebes, northern shovelers, ruddy ducks, American avocets, black-necked stilts, white-faced ibis, burrowing owls, greater roadrunners, black skimmers, gull-billed terns and yellow-footed gulls are among the species associated with the refuge. Sensitive wildlife includes the Yuma Ridgway’s rail, western snowy plover, mountain plover and desert pupfish.

The checklist total is cumulative, not a one-day promise. Water, farming, weather and migration timing continually change what is present. Current sightings are best checked at the visitor-center bulletin board or by calling the refuge.

For a broader route beyond the refuge, the complete Salton Sea bird-watching guide connects Sonny Bono with Imperial Wildlife Area, the state recreation area and the north shore.

Wildlife by season

Winter: geese, cranes and the biggest spectacle

November through February offers the strongest combination of migration, mild weather and visitor services. More than 200 bird species may be present, including large flocks of snow and Ross’s geese, sandhill cranes, ducks, shorebirds, herons and ibis. Refuge fields provide forage for more than 30,000 wintering geese.

Spring: departures and northbound migrants

Departing geese, ducks and shorebirds overlap with northbound migrants arriving from farther south, including warblers and blackbirds. American kestrels, northern harriers and burrowing owls enter their nesting season.

Summer: nesting birds and extreme heat

Greater roadrunners, Gambel’s quail and verdins raise young alongside Yuma Ridgway’s rails, Western gull-billed terns and black skimmers. Late summer can bring yellow-footed gulls, but it also brings dangerous heat: May-through-October temperatures routinely exceed 100°F, with 116°F to 120°F recorded. The visitor center is closed in summer.

Fall: the return migration

Shorebirds return as early as August, and staff begin flooding ponds in late August or early September. Migration generally peaks around November, when northern shovelers, ruddy ducks and geese become increasingly visible.

Two units, two different experiences

The refuge’s two management units are about 18 miles apart. They are not interchangeable, and the official acreage does not represent one continuous public park.

Visitor area	Best reason to stop	What is there
Headquarters / Unit 2	Orientation, facilities, landscape overview and Rock Hill	Seasonal visitor center, bookstore, observation tower, picnic area, flush restrooms, drinking fountain and the approximately two-mile Rock Hill Trail
Unit 1	Closer access to concentrated managed-wetland habitat	Hardenberger Trail, two renovated photo blinds, observation tower and platform, kiosk and small outhouse near Bannister and Vendel roads

Headquarters, visitor center and Rock Hill Trail

Headquarters at 906 West Sinclair Road is the most straightforward first stop. In winter, its volunteer-staffed visitor center offers maps, a bird diorama, recent-sighting information and a small bookstore. An observation tower overlooks fields and wetlands.

Rock Hill Trail begins near the parking area and covers approximately two miles round trip. Official pages disagree on whether it is a loop or out-and-back route, so the current map and posted signs should guide the walk. The trail crosses several habitats before climbing Rock Hill for broad views.

Rock Hill is a rhyolite volcanic dome within the Salton Buttes volcanic field. The U.S. Geological Survey places the field’s most recent eruption about 1,800 years ago and identifies the region as geothermally and seismically active.

Unit 1 and Hardenberger Trail

Unit 1 is accessed at Vendel and Bannister roads and contains most publicly accessible refuge wetlands. Its approximately 0.8- to 0.9-mile Hardenberger Trail loops around a freshwater pond and leads to a photo blind, observation deck and observation tower. Unit 1 as a whole has two renovated photo blinds.

Unit 1 offers the more concentrated wetland experience. Headquarters remains better for orientation, full restrooms, drinking water and the Rock Hill landscape.

Bird watching and photography

Early morning usually brings cooler temperatures, softer light and more visible feeding or flight activity. Late afternoon can bring warm light and movement toward evening roosts. Midday heat shimmer makes distant birds harder to study or photograph.

Binoculars are useful; a spotting scope or long lens is better for distant birds. Towers, platforms and blinds provide the intended viewing points. Quiet movement and patience produce better results than approaching wildlife. Closed roads, levees, farm fields and posted sanctuaries are not shortcuts to a photograph. Recreational drones may not be launched, landed or operated from refuge property.

Mark Miller’s field notes from an October visit show the refuge as it actually feels on the ground: enormous sky, distant water, agricultural edges and birds appearing in layers rather than in a single curated viewpoint.

A sanctuary on a shrinking sea

The modern Salton Sea formed in 1905 when Colorado River water entered an ancient lake basin that had repeatedly filled as Lake Cahuilla. The present sea has no outlet. Water leaves mainly through evaporation, salts remain behind and reduced agricultural inflow has accelerated shoreline retreat.

Increasing salinity has diminished fish populations and altered food webs. Receding water creates marshes near agricultural drains but also exposes playa and contaminants. Biologists monitor birds, disease and heavy metals while staff use prescribed fire, farming and water-level management to maintain habitat.

This work does not return the Salton Sea to one fixed historical moment. It keeps habitat functioning while the lake changes—a living demonstration of conservation in an ecosystem dependent on water infrastructure, agriculture and continual human decisions.

Planning a visit

Headquarters: 906 West Sinclair Road, Calipatria, CA 92233-9744
Phone: (760) 348-5278
Admission: Free
Outdoor hours: Sunrise to sunset

As of July 29, 2026, the visitor center is closed for its normal summer season. Trails, observation platforms and bathrooms remain open from sunrise to sunset. The official seasonal schedule generally lists the building as open Tuesday–Sunday, 8 a.m.–3:30 p.m., from November through April, subject to volunteer availability and holiday closures. A phone call is recommended before a trip that depends on entering the building.

Flush restrooms and a drinking fountain are available at headquarters; Unit 1 has a small outhouse. Carrying water remains essential. FWS reports daily temperatures above 100°F from May through October, with 116°F to 120°F recorded annually. Trail walks should be skipped during extreme-heat warnings, and no air-conditioned refuge building should be expected during the summer closure. Western diamondback rattlesnakes also occur here, making designated trails and careful footing important.

Pets must remain leashed, camping is prohibited and posted closures must be respected. Designated waterfowl hunting occurs in Unit 2 from October through February; hunters check in through the Wister Hunt Station, and all visitors should observe current signs.

Headquarters is reached from Highway 111 by turning west onto Sinclair Road about four miles south of Niland. Unit 1 is separate at Vendel and Bannister roads; official directions from Interstate 8 use Forrester Road north through Westmorland and then Gentry Road.

The official maps should be downloaded before departure. FWS does not clearly certify the public trails or towers as wheelchair-accessible; visitors needing accommodations should call ahead. Salton Sea State Recreation Area provides a different shoreline perspective farther north.

Why this refuge matters

Sonny Bono Salton Sea National Wildlife Refuge is neither a celebrity memorial with birds around it nor untouched wilderness. It is a 1930 sanctuary carrying a 1998 commemorative name, with much of its original federal acreage now submerged and its wildlife habitat sustained through managed wetlands and fields. Its wildlife reveals the Salton Sea’s continuing ecological power; its ponds, crops and monitoring reveal how much work survival now requires.

Frequently asked questions

Is the Sonny Bono Salton Sea National Wildlife Refuge open, and is there a fee?

Admission is free, and trails, platforms and bathrooms open from sunrise to sunset. The visitor center is generally open Tuesday–Sunday, 8 a.m.–3:30 p.m., November–April, subject to volunteer availability; it closes in summer and on federal holidays.

What is the best time to visit for bird watching?

November through February combines cooler weather with snow and Ross’s geese, sandhill cranes, ducks, shorebirds and raptors. Spring and fall bring migration turnover; summer offers nesting birds and possible yellow-footed gulls but dangerous heat.

What is the difference between Unit 1 and Unit 2?

Unit 2 contains headquarters, the visitor center, full restrooms, drinking water and Rock Hill Trail. Unit 1, near Bannister and Vendel roads, offers concentrated wetlands, Hardenberger Trail, photo blinds, an observation tower, a platform and an outhouse.

How long is Rock Hill Trail, and is Rock Hill an active volcano?

The trail is approximately two miles round trip. Rock Hill is a rhyolite dome in the geothermally and seismically active Salton Buttes field, whose most recent eruption occurred about 1,800 years ago. Because official route descriptions conflict, the current map and posted signs should be followed.

Why is the refuge named after Sonny Bono?

Congressman Sonny Bono advocated federal attention to the Salton Sea’s environmental crisis. After his death, Public Law 105-372 renamed the existing refuge in his honor on November 12, 1998. The refuge itself dates to 1930.

Sources and further reading

• U.S. Fish and Wildlife Service: Sonny Bono Salton Sea National Wildlife Refuge

• U.S. Fish and Wildlife Service: current visitor information and seasonal hours

• U.S. Fish and Wildlife Service: refuge history, acreage and mission

• U.S. Fish and Wildlife Service: wildlife and birding by season

• U.S. Fish and Wildlife Service: habitat, farming and wildlife management

• U.S. Fish and Wildlife Service: official refuge and trail maps

• U.S. Fish and Wildlife Service: current trail descriptions

• U.S. Fish and Wildlife Service: refuge rules and policies

• U.S. Fish and Wildlife Service: refuge brochure and pet rules

• U.S. Fish and Wildlife Service: keeping wildlife safe from drones

• Executive Order 5498: establishment of the Salton Sea Wild Life Refuge

• Public Law 105-372: 1998 renaming and Salton Sea legislation

• U.S. Geological Survey: Salton Buttes

Blogs 👇

- Egrets and Cranes: A Day at the Salton Sea Refuge