Marin Islands are the two island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

s, East Marin and West Marin, situated offshore from San Rafael, California

San Rafael, California

San Rafael is a city and the county seat of Marin County, California, United States. The city is located in the North Bay region of the San Francisco Bay Area...

 in the San Pablo Bay

San Pablo Bay

San Pablo Bay is a tidal estuary that forms the northern extension of San Francisco Bay in northern California in the United States. Most of the Bay is shallow; however, there is a deep water channel approximately in mid bay, which allows access to Sacramento, Stockton, Benicia, Martinez, and...

 extension of San Francisco Bay

San Francisco Bay

San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...

. The islands comprise the Marin Islands National Wildlife Refuge, which was established in 1992. Surrounding submerged tidelands are also included in the refuge

Wildlife refuge

A wildlife refuge, also called a wildlife sanctuary, may be a naturally occurring sanctuary, such as an island, that provides protection for species from hunting, predation or competition, or it may refer to a protected area, a geographic territory within which wildlife is protected...

.

West Marin Island, elevation 26 metres (85.3 ft) above the bay

Bay

A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...

 waters, supports the largest 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"....

 and 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...

 in the San Francisco Bay Area

San Francisco Bay Area

The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...

. Nesting species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 include great egret

Great Egret

The Great Egret , also known as the Great White Egret or Common Egret, White Heron, or Great White Heron, is a large, widely-distributed egret. Distributed across most of the tropical and warmer temperate regions of the world, in southern Europe it is rather localized...

s, snowy egret

Snowy Egret

The Snowy Egret is a small white heron. It is the American counterpart to the very similar Old World Little Egret, which has established a foothold in the Bahamas....

s, great blue heron

Great Blue Heron

The Great Blue Heron is a large wading bird in the heron family Ardeidae, common near the shores of open water and in wetlands over most of North and Central America as well as the West Indies and the Galápagos Islands. It is a rare vagrant to Europe, with records from Spain, the Azores and England...

s, and black-crowned night heron

Black-crowned Night Heron

The Black-crowned Night Heron commonly abbreviated to just Night Heron in Eurasia, is a medium-sized heron found throughout a large part of the world, except in the coldest regions and Australasia .-Description:Adults are...

s.

East Marin Island, a former vacation retreat, now supports a variety of introduced and native plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s and provides critical nesting material and rest sites for the nearby colony.

Submerged tidelands support a variety of resident and migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 water bird

Water bird

The term water bird or waterbird is used to refer to birds that live on or around water. Some definitions apply the term especially to birds in freshwater habitats, though others make no distinction from birds that inhabit marine environments. In addition, some water birds are more terrestrial or...

s such as surf scoter

Surf Scoter

The Surf Scoter is a large sea duck, which breeds in Canada and Alaska. It is placed in the subgenus Melanitta, along with the Velvet and White-winged Scoters, distinct from the subgenus Oidemia, Black and Common Scoters.It winters further south in temperate zones, on the coasts of the northern USA...

, black oystercatcher, diving duck

Diving duck

The diving ducks, commonly called pochards or scaups, are a category of duck which feed by diving beneath the surface of the water. They are part of the diverse and very large Anatidae family that includes ducks, geese, and swans....

s, and osprey

Osprey

The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...

. Refuge objectives are to protect migratory species, including the heron and egret nesting colony, protect and restore suitable habitat

Habitat (ecology)

A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...

 for the colony, and protect the tidal mud flats and unique island ecosystem

Ecosystem

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

.

The islands are the property of the U.S. Fish and Wildlife Service and require special permission to visit. They were donated to the federal government by the Crowley family of San Francisco They had been bought by Thomas Crowley at auction in 1926 for $25,000, in the hope that they would become the western terminus of the Richmond - San Rafael Bridge. Instead, they became a family vacation spot for more than sixty years.