Sanctuary Integrated Monitoring Network
Greater Farallones National Marine Sanctuary

Seabirds and Shorebirds

Brown Pelicans
Brown Pelicans. Photo: GFNMS Library
One of the most spectacular components of the Gulf of the Farallones National Marine Sanctuary's abundant and diverse marine life are the populations of nesting and migratory seabirds: it hosts more than 300,000 breeding seabirds – the largest concentration in the contiguous United States. These birds are highly dependent on the sanctuary's productive waters.

Thirteen bird species have breeding colonies on the Farallon Islands and feed in the sanctuary (see Table 1). More than 160 species use the sanctuary for shelter, food or as a migration corridor. Of these, 57 species are known to use the sanctuary during their breeding season.

At least 19 marine and coastal bird species that are federally listed as threatened, endangered or a species of concern can be found here, including the Marbled Murrelet, Brachyramphus marmoratus, and the Western Snowy Plover, Charadrius alexandrinus nivosus.

Seabirds are those birds whose normal habitat and food source is the marine environment, whether coastal, offshore or pelagic. They can be divided by their feeding strategies into surface feeders, surface swimmers/pursuit divers, deep-plunge divers and scavengers/pirates (those who steal from other birds). These strategies are reflected in their anatomy, physiology and habitat niche.

The surface feeders are aerially agile birds that feed from the surface while in flight, such as the albatross and frigatebird. Black-footed Albatross, Phoebastria nigripes, and Laysan Albatross, Phoebastria immutabilis are common in the sanctuary and have wingspans that exceed two meters (seven feet). Long, slender and powerful wings allow these birds long-distance and near-effortless flights extending to more than 2,400 kilometers (1,490 miles). The truly pelagic species such as albatross and shearwaters spend up to nine months at sea, coming to land only to rear their young.

The surface swimmers and pursuit-diving birds are a diverse group but have in common wide wings that enhance their swimming and diving abilities. They include the alcids, cormorants, loons and grebes and are often seen simply sitting on the water's surface when they are not diving for food.

Murres, guillemots, murrelets, auklets and puffins belong to the alcid family and are highly adapted to life at sea. Many alcids live a truly pelagic existence, residing on the ocean's surface except when rearing their young. Common Murres, Uria aalge, and Cassin's Auklets, Ptychoramphus aleuticus, are the most abundant species on the Farallon Islands, numbering in the tens of thousands. The Common Murre has been known to dive to depths of more than 190 meters (623 feet).

Cormorants, loons and grebes are examples of underwater pursuit divers. Cormorants have diminished waterproofing compared to many other seabirds. For example, their feathers get saturated with water, which allows them to dive to deeper depths pursuing their prey. They can often be seen along the coastline, gathering in large numbers on craggy rocks, holding their wings open to dry.

Long-billed Curlew Numenius americanus foraging.

Black-bellied Plover Pluvialis squatarola, which is the largest of the North American Plovers. Observed in the northern marsh just past the Jetty Road culvert.

Six grebe species make their winter home in the sanctuary, including the Eared, Podiceps caspicus, Horned, P. auritus, and Western, Aechmophorus occidentalis. These birds are excellent swimmers and divers. They have been known to use their wings to "fly" underwater as they hunt for small fishes. Grebes are usually found on the coastal shores of sanctuary waters, although they do form large groupings on the open ocean.

Four species of loon spend time within California estuaries during their migration. Loons are large aquatic birds, known for their eerie calls, that feed on various fish species down to depths of 80 meters, capturing prey with their strong dagger-like bills.

Terns, gulls, shearwaters and pelicans can often be observed from sanctuary shorelines splashing down from great heights as they plunge-dive after prey. The Brown Pelican, Pelecanus occidentalis californicus, is one of the great recovery stories for endangered species. Plagued by DDT, the pelican population was brought to the edge of extinction until the banning of the pesticide in 1972.

Pelicans are abundant in the sanctuary during the summer and fall, cruising over the breakers in a single-file line. These birds are now doing so well that it is expected that they will soon be de-listed or downgraded from endangered to threatened status (on the federal endangered species list).

Gulls, kittiwakes, fulmars, skua and jaegers feed on a variety of prey as scavengers and pirates. The most prolific species along the Pacific Coast, the Western Gull, Larus occidentalis, has established itself in urban areas as well, feeding from garbage dumps and dumpsters.

The sanctuary holds crucial habitat for numerous shorebird species. The term shorebird, or "wader," refers to any bird that relies on beaches or wetlands for feeding and nesting habitat.

Approximately 80 of the more than 400 shorebird species are found within sanctuary boundaries. Easily recognizable members include the Willet, Catoptrophorus semipalmatus, Sanderling, Calidris alba, and Marbled Godwit, Limosa fedoa. Within the sanctuary, shorebirds can be seen at Abbotts Lagoon, Bolinas Lagoon, Tomales Bay, Bodega Bay, Estero Americano and Estero de San Antonio as well as many areas along the shore, such as Fitzgerald Marine Reserve and at Ocean, Drakes, Limantour and Doran Beaches.

More than 27 shorebird species – such as the stunning Black Oystercatcher, Haematopus bachmani, two species of dowitcher and several species of sandpiper – are regularly seen here. Generally, these birds probe about the shores feeding on buried clams, worms, crustaceans and small fishes. A notable "prober," the Long-billed Curlew, Numenius americanus, has the longest beak (up to 23 centimeters, or nine inches) of any shorebird.

In contrast to the "probers," the "gleaners" scurry along the beach feeding on invertebrates on the sand surface. Sanderlings, for example, gather in large numbers to glean the beach. The Western Snowy Plover, once an abundant species along the Pacific coast, has declined to such a low population size that it is listed as threatened on the federal endangered species list. Another plover, the Killdeer, Charadrius vociferus, is best known for its screeching calls and the ability to pretend an injury in order to lure predators away from its nest.

Other Coastal and Aquatic Birds
Herons, ducks and rails are seen in the sanctuary region and deserve mention here.

The Black Rail, Laterallus jamaicensis, listed as threatened on California's endangered species list, can be found in Tomales Bay, sanctuary estuaries and the marsh of the Point Reyes National Seashore. Faced with rapidly diminishing habitat, rails are now rarely found in the salt marshes of bay and coastal communities.

At least seven species of heron, egret and bittern live in the sanctuary and adjacent wetlands. These long-necked wading birds are found in wetlands and along the shoreline.

More than 20 species of waterfowl inhabit the Gulf of the Farallones and surrounding waters, with many of them present year-round. The Canada Goose, Branta canadensis, Surf Scoter, Melanitta perspicillata, and Red-breasted Merganser, Mergus serrator, are seasonal visitors to the area along with the elegant Northern Pintail, Anas acuta. Diversity is quite strong in these waterfowl, with species displaying great variation in color, size, shape and feeding behavior.

Human impacts to bird populations worldwide include competition for food with commercial and recreational fisheries; entanglement in fishing gear; ingestion of marine debris; and disturbance of roosting and breeding birds by watercraft, aircraft and human visitors. Environmental contamination from the historical use of pesticides may still affect some species.

Oil spills are a very real danger, also. The 1998 Command oil spill resulted in injuries to many seabirds – mostly Common Murres but also Brown Pelicans, Marbled Murrelets and other species.

In addition, a number of small oil spills in the region have injured and killed many seabirds, including Common Murres and Rhinoceros Auklets, Cerorhinca monocerata, in neighboring central California sanctuaries. The possibility of a large oil spill from tankers transiting sanctuary waters is an ongoing threat to seabirds and shorebirds.

Seabirds and shorebirds from over 50 species were collected live and dead as a result of the November, 2007 Cosco Busan oil spill in San Francisco Bay. Birds most heavily impacted in were Surf Scoters, grebes, scaups, murres, and gulls. The potential long term effects on these and other sanctuary bird populations are still being evaluated. For more information see the Natural Resource Damage Assessment and Restoration report.

In addition to human impacts, changes in climate and oceanographic conditions also affect bird populations. The prevalence of marine birds using sanctuary waters changes from year to year due to fluctuations in marine conditions, including El Niño, Pacific Decadal Oscillations, and changes in intensity and timing of upwelling conditions in the spring/summer. For example, the reproductive success of Cassin's Auklets (a species that feeds heavily within sanctuary waters) on the Farallon Islands appears to be intricately dependent on the timing and intensity of oceanographic upwelling conditions, which influences food availability (especially krill) during critical life history stages.


Many ongoing monitoring efforts help ensure the continued protection of our valuable resources. The following list includes some of the projects underway in the sanctuary. Please click on the Projects tab at the top of this page for more information.

Sanctuary Ecosystem Assessment Surveys (SEA Surveys)
SEA Surveys is a compilation of Gulf of the Farallones National Marine Sanctuary monitoring programs that provide the biological observations and habitat characterization for the gulf region. These include several long-term, established monitoring programs of the regions pelagic and coastal habitats that monitor the status, trends and distribution of the sanctuary's seabird and coastal bird populations. The SEA Surveys-Pelagic Habitat project, for example, is designed to investigate the relationship between hydrographic conditions, physical features and the distribution and abundance of marine organisms in the Gulf of the Farallones and Bodega Bay regions.

Beach Watch
This long-term beach monitoring program's goal is to develop status and trend information on the sanctuary's shoreline biological resources. Trained volunteers conduct surveys every two to four weeks. Surveyors document living and dead wildlife; restoration recovery; visitor-use patterns, wildlife disturbance and violations; chronic and catastrophic oil pollution; and detection of ecosystem changes such as El Niño and upwelling events.

PRBO Conservation Science
This non-governmental organization also conducts ecosystem studies and monitors shorebirds, seabirds, marine mammals and white sharks in areas
Major Seabird Colonies Map
Figure 1. Major seabird colonies within the Gulf of the Farallones National Marine Sanctuary. Map produced by Tim Reed, GFNMS/SIMoN. [View Larger]
within Cordell Bank, Gulf of the Farallones and Monterey Bay National Marine Sanctuary waters, such as the Farallon Islands and Año Nuevo Island. The group provides recommendations to partner agencies such as the National Oceanic Atmospheric Administration (NOAA) National Marine Sanctuary Program, U.S. Fish and Wildlife Service, and California Department of Parks and Recreation on how to enhance, protect and conserve these important wildlife populations.

Seabird Protection Network
This effort, spearheaded by the Gulf of the Farallones National Marine Sanctuary and in cooperation with the U.S. Fish and Wildlife Service Common Murre Restoration Project and other agencies, sanctuaries and non-governmental organizations, is aimed at improving the survival and recruitment of California coast seabird colonies. The program addresses one of the biggest obstacles to the recovery of these populations: human disturbances. The goal is to reduce human disturbances at seabird breeding and roosting sites along the California coast.

The founding Chapter of the Seabird Protection Network, Bodega Head – Pt. Sur, developed a framework for collaboration among groups who oversee similar projects. The structure of the Network is modeled on the Audubon Society chapter structure. Gulf of the Farallones National Marine Sanctuary, who manages the founding Chapter, facilitates program expansion and incorporates Chapters as they develop. Currently, the Seabird Protection Network extends from the Mendocino County line to Point Mugu, and out to the Channel Islands.

Table 1. Bird Species that Breed on the Farallon Islands

Common Name Scientific Name
Leach's Storm-Petrel Oceanodroma leucorhoa
Ashy Storm-Petrel Oceanodroma homochroa
Double-Crested Cormorant Phalacrocorax auritus
Brandt's Cormorant Phalacrocorax penicillatus
Pelagic Cormorant Phalacrocorax pelagicus
Western Gull Larus occidentalis
California Gull Larus californicus
Common Murre Uria aalge
Pigeon Guillemot Cepphus columba
Cassin's Auklet Ptychoramphus aleuticus
Rhinoceros Auklet Cerorhinca monocerata
Tufted Puffin Fratercula cirrhata
Black Oystercatcher Haematopus bachmani