Sutter National Wildlife Refuge, the southern-most refuge in the Sacramento National Wildlife Refuge Complex

Sacramento National Wildlife Refuge Complex

The Sacramento National Wildlife Refuge Complex is part of the United States system of National Wildlife Refuges . It is located in northern California, in the valley of the Sacramento River....

, is located in the Sacramento Valley

Sacramento Valley

The Sacramento Valley is the portion of the California Central Valley that lies to the north of the San Joaquin-Sacramento Delta in the U.S. state of California. It encompasses all or parts of ten counties.-Geography:...

 of California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, about 50 miles (80.5 km) north of the metropolitan area of Sacramento

Sacramento, California

Sacramento is the capital city of the U.S. state of California and the county seat of Sacramento County. It is located at the confluence of the Sacramento River and the American River in the northern portion of California's expansive Central Valley. With a population of 466,488 at the 2010 census,...

. The refuge consists of about 2600 acres (10.5 km²), consisting primarily of wetland

Wetland

A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

 impoundment

Impoundment

Impoundment is the election of a President of the United States not to spend money that has been appropriated by the U.S. Congress. The precedent for presidential impoundment was first set by Thomas Jefferson in 1801. The power was available to all presidents up to and including Richard Nixon, and...

s with some riparian and grassland

Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

 habitat.

About 80 percent of the refuge is located in the Sutter Bypass, a floodwater bypass from the Sacramento River

Sacramento River

The Sacramento River is an important watercourse of Northern and Central California in the United States. The largest river in California, it rises on the eastern slopes of the Klamath Mountains, and after a journey south of over , empties into Suisun Bay, an arm of the San Francisco Bay, and...

 that floods at least once a year and may cover portions of the refuge with up to 12 feet (3.7 m) of water. Sutter Refuge typically supports wintering populations of more than 175,000 duck

Duck

Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...

s and 50,000 geese

Goose

The word goose is the English name for a group of waterfowl, belonging to the family Anatidae. This family also includes swans, most of which are larger than true geese, and ducks, which are smaller....

.

The mixed riparian forest habitat on the refuge is important for breeding and migrating passerine

Passerine

A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...

 birds, and supports a large heron

Heron

The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....

/egret

Egret

An egret is any of several herons, most of which are white or buff, and several of which develop fine plumes during the breeding season. Many egrets are members of the genera Egretta or Ardea which contain other species named as herons rather than egrets...

 rookery

Rookery

A rookery is a colony of breeding animals, generally birds. A rook is a Northern European and Central Asian member of the crow family, which nest in prominent colonies at the tops of trees. The term is applied to the nesting place of birds, such as crows and rooks, the source of the term...

. The refuge provides habitat for several Federal and State endangered

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 and threatened species

Threatened species

Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...

, including giant garter snake, winter-run Chinook salmon

Chinook salmon

The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the pacific salmon family. Other commonly used names for the species include King salmon, Quinnat salmon, Spring salmon and Tyee salmon...

, yellow-billed cuckoo

Yellow-billed Cuckoo

The Yellow-billed Cuckoo, Coccyzus americanus, is a cuckoo. Common folk-names for this bird in the southern United States are Rain Crow and Storm Crow...

, and Swainson's hawk

Swainson's Hawk

The Swainson's Hawk , is a large buteo hawk of the Falconiformes, sometimes separated in the Accipitriformes like its relatives. This species was named after William Swainson, a British naturalist...

.