Photo: Sophie Webb
Oceanographic upwelling that originates from Point Arena provides conditions that are favorable for productivity of krill and small fishes, creating rich feeding grounds for seabirds here in the sanctuary. In addition, the proximity of very deep water close to the shallow feature of Cordell Bank creates unique local conditions for high productivity and optimal conditions for seabird foraging.
The composition of the seabird community within the sanctuary, like that of the fishes and marine mammals, is a mix of permanent and seasonal residents as well as species that use sanctuary waters for shorter time periods, either as a feeding destination or in transit during long-distance migratory journeys.
The majority of seabird species here are seasonal residents that breed in sites such as New Zealand, Chile and Alaska and then come here to feed during their non-breeding season. Among these is the Sooty Shearwater, which can number in the tens of thousands and is the most abundant seabird species off California.
Permanent resident bird species nest on the nearby Farallon Islands and in the Point Reyes area. For example, Cassin's Auklets, which nest on the Farallon Islands, feed in Cordell Bank waters throughout the year and are one of the most numerous seabirds found in the sanctuary when krill is present (but can be virtually nonexistent here in the absence of krill).
In contrast, the Black-footed Albatross breeds thousands of miles from here yet still relies on the sanctuary's rich food resources to feed its young. This amazing feat was documented in a recent study using satellite tags; it showed that albatrosses nesting on Tern Island and Midway Atoll in the northwestern Hawaiian Islands "commute" to Cordell Bank to gather food for their chicks. Other migratory species, including jaegers, phalaropes and Arctic Terns, use the productive waters around the bank as a stopover on their annual migration route.
Most of the species found in the waters surrounding Cordell Bank are "pelagic" birds, which only spend time on land to breed. Notable examples include Black-footed Albatross, Ashy Storm-Petrel, Sooty Shearwater and Pink-footed Shearwater during the summer and the fall, and Northern Fulmars during the winter and the spring. Other seabirds that frequent the sanctuary spend a large proportion of their time on land and in coastal areas, including several species of gulls, which are more common in the area of Cordell Bank in the winter.
Sanctuary waters are important to several bird species that are of special concern because of their small or declining populations. These population conditions may be a result of environmental change, habitat degradation, disease, human exploitation or a combination of these factors. Special-status species (based on listings by state, federal and/or international agencies and organizations) that are relatively abundant or common in the sanctuary include Black-footed Albatross, Ashy Storm Petrel, Pink-footed Shearwater, Cassin's Auklet and Buller's Shearwater.
Human impacts to seabird 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 and aircraft. Environmental contamination from the historical use of pesticides may still affect some species.
A number of small oil spills in the region have injured and killed many seabirds, including Common Murres and Rhinoceros Auklets, in neighboring central California sanctuaries. The possibility of a large oil spill from tankers transiting sanctuary waters is an ongoing threat to seabirds.
Pied-Billed Grebe Podilymbus podiceps.
Likely Long-billed Dowitchers Limnodromus scolopaceus. They were foraging in the northern marsh just past the Jetty Road culvert.
MonitoringApplied California Current Ecosystem Studies (ACCESS)
ACCESS is a research partnership to support integrated ocean management in northern and central California. PRBO Conservation Science, Cordell Bank and Gulf of the Farallones National Marine Sanctuaries have been investigating the spatial and temporal relationships between oceanographic processes, zooplankton, and marine birds and mammals in the region surrounding Cordell Bank and the Gulf of the Farallones. This project has several objectives, including: 1) Understand how the timing, intensity, and duration of upwelling influences the distribution and abundance of euphausiids (better known as krill) thus affecting the distribution and abundance of krill predators in the region; 2) Identify persistent locations of predator and prey aggregations and potential areas of high trophic transfer in the Gulf of the Farallones region that may be associated with bathymetric and hydrographic features; 3) Monitor physical and biological characteristics of the pelagic ecosystem, with the goal of developing indicators of ecosystem health, to understand change on a variety of scales and detect natural and anthropogenic impacts.
Research cruises have been conducted in spring, summer and fall (three to five cruises per year) from 2004 to the present. This study has shown large inter-seasonal and inter-annual differences in lower trophic level abundance as well as predator presence in the sanctuaries. This assessment of the pelagic system specifically meets the sanctuary's mandate to conduct long-term monitoring of the resources within the sanctuary and provides important information for resource protection and management.
Cordell Bank Ocean Monitoring Program
The goal of the Cordell Bank Ocean Monitoring Program (CBOMP) is to characterize and monitor the spatial and temporal variability in the physical and biological components of the pelagic ecosystem in the region surrounding Cordell Bank. Weather and ocean conditions permitting, researchers with Cordell Bank National Marine Sanctuary conducted single-day cruises monthly (sometimes seasonally) from 2004 to2010. Data on the abundance of seabirds, marine mammals, other vertebrates and marine debris were collected by trained observers along six 12-kilometer east-west transects centered on Cordell Bank. Physical and biological characteristics of the pelagic system were measured along transects using a CTD (vertical profiles of salinity, temperature, chlorophyll-a, and light levels at set stations), TSG (continuous surface values of salinity, temperature, chlorophyll-a) and echo sounder (continuous measurements of relative abundance of zooplankton).
Preliminary analyses of seabird data collected during the CBOMP suggest that the degree of interannual variation in bird density depends on the type of foraging strategy. Opportunistic feeders that are seasonal residents to the Cordell Bank region do not exhibit as strong a variation among years with different oceanographic conditions compared to specialist predators that are permanent resident birds and are more sensitive to changes in oceanographic conditions among years.
Tracking Black-Footed Albatross Movements and Conservation
The Black-footed Albatross, Phoebastria nigripes, has recently been listed as endangered by the World Conservation Union (IUCN). Assessing albatross movements and habitats during the post-breeding season is a top conservation priority.
Since 2004, the sanctuary has been supporting research by Oikonos Ecosystem Knowledge to study the post-breeding migration patterns and movements of Black-footed Albatross in the eastern Pacific Ocean. Twenty-eight birds were tagged in central California during the first three years of this study (2004-2005, 2007). Males and females were found to occupy different oceanic regions during the post-breeding season, with males venturing farther west than females. Data from 2004-2005 indicate that the tracked birds spent approximately 60 percent of their time in the high seas beyond national Exclusive Economic Zones. Of the time spend in U.S. territorial waters, 42 percent was spent within the three central California national marine sanctuaries.
CSCAPE: Collaborative Survey of Cetacean Abundance and the Pelagic Ecosystem
CSCAPE is a collaboration between the National Oceanic and Atmospheric Administration (NOAA) Fisheries and the National Marine Sanctuary Program to assess the abundance and distribution of marine mammals and characterize the pelagic ecosystem off the U.S. West Coast. Cruises are conducted every three years and cover the entire West Coast, from the northern boundary of Washington to the southern boundary of California, including concentrated sampling within the West Coast sanctuaries.
The project has three objectives:
- to conduct a marine mammal assessment survey within approximately 300 nautical miles of the shore, with additional fine-scale surveys within the sanctuary boundaries
- to characterize the pelagic ecosystem within the study area through the collection of underway and station-based biological and oceanographic data, seabird studies and acoustic sampling
- to conduct biopsy sampling and photo-identification studies of special-interest species
Tagging of Pacific Pelagics (TOPP)
A pilot program of the Census of Marine Life, the Tagging of Pacific Pelagics (TOPP) research project is part of an international endeavor to determine what lives in the world's ocean. TOPP scientists explore the Pacific using satellite-tagged animals to gather data about their world. The results coming from these satellite-based research projects are expanding our understanding of marine wildlife and the role of the sanctuary in their feeding and migratory patterns. Seabirds that are tagged as part of the TOPP program include Pink-footed Shearwaters, Black-footed Albatrosses, Laysan Albatrosses and Sooty Shearwaters.