Channel Islands - Northern

The northern Channel Islands lie south of Santa Barbara and Ventura, off the coast of southern California, and their peaks looming offshore are a familiar sight to millions residents of the Los Angeles metropolitan area. For a variety of reasons, they have remained virtually undeveloped, and thus represent some of the best examples of aspects of pre-settlement southern California. Four are arranged in an east-west chain, San Miguel (9000 acres), Santa Rosa (50,000 acres), Santa Cruz (60,000 acres) and tiny Anacapa (700 acres). Santa Barbara (640 acres) lies to the southeast, and San Nicolas (13,000 acres), southwest of here, is the most isolated of the islands. Santa Catalina Island (a.k.a. Catalina, 50,000 acres), to the southeast, is due south of Los Angeles. All except Catalina are managed by the federal government, with San Nicolas operated as a U.S. Navy Base and the remaining five under Channel Islands National Park. The waters off the northern islands, San Miguel, Santa Rosa, Santa Cruz, Anacapa and Santa Barbara have also been recognized as one of three National Marine Sanctuaries (NOAA) in California. Nearly 90% of Catalina is owned by the non-profit Santa Catalina Island Conservancy, a conservation group, and it is the only island with a permanent town, Avalon. Both Santa Rosa and Santa Cruz have in-holdings of private land (large ranches) that pre-date their park designation.

(note: Islands were mapped with a 1-mile buffer)

Ornithological Summary

As with most large islands on earth, several bird taxa have evolved here in isolation and are not found elsewhere, with each island sharing some races and not others. Of the sensitive endemic taxa, their distribution is as follows: Catalina California Quail (native to Catalina and introduced to Santa Cruz and Santa Rosa, fide Garrett and Dunn 1981), Island Loggerhead Shrike (all except San Nicolas), Catalina Hutton's Vireo (Santa Catalina), San Clemente Spotted Towhee (Santa Catalina and Santa Rosa), Santa Cruz Island Rufous-crowned Sparrow (Santa Cruz and Anacapa) and Channel Islands Song Sparrow (San Miguel and Santa Rosa). Island Scrub-Jay a recently-split species not currently considered sensitive occurs only on Santa Cruz Island. This IBA is the single most important seabird nesting area in southern California, with birds concentrated on coastal bluffs and on large offshore rocks around each island (except San Nicolas and Catalina). Three seabird taxa, California Brown Pelican, Black Storm-Petrel and Xantus' Murrelet do not nest regularly elsewhere in the U.S. Though Black Storm-Petrels are much more common in the Gulf of California, the population of Brown Pelicans represents about 10% of the global population of the californicus race, our local subspecies. The entire U.S. breeding population of Xantus' Murrelet is confined to the Channel Islands (the endemic scrippsii race), with the largest colony on Santa Barbara Isl. (1400 birds, Carter et al. 1992). Tiny Prince Island, off San Miguel Isl., hosts nearly 20% the state's breeding Cassin's Auklets (c. 9,000, Carter et al. 1992). Several other seabirds, including Rhinoceros Auklet and Tufted Puffin, formerly bred more widely within this IBA, but were extirpated by rats and other introduced pests except for a remnant population on and around San Miguel Isl. (Carter et al. 1992). The northern Channel Islands population of Snowy Plovers (breeding on Santa Rosa, San Miguel and San Nicolas Isl.) is comprised of 250-400 birds (J. Greaves, in litt.), the largest concentration of the coastal-breeding Western Snowy Plover in the world. Most of the breeding Peregrine Falcons in southern California nest here, as well as several endemic races of songbirds whose relatedness to each other (and to mainland birds) is still being debated. Burrowing Owl and both Mountain Plover and Pacific Golden-Plover winter on the windswept grasslands of San Nicolas (W. Wehtje, pers. comm.), and each island supports large numbers of migrant songbirds, particularly in fall.
The Channel Islands North IBA contains 15 seabird species and an estimated 74,222 birds. The colony is an IBA for the following species: Western Gull (13,540), Ashy Storm-Petrel (1,675), Brandt's cormorant (28,625), and Xantus's murrelet (218). The following species are on the Audubon WatchList: Ashy Stormpetrel.
Anacapa Island supports 30-35 thousand breeding seabirds. The largest western United States colony of Brown Pelicans nests here, which constitutes about 10% of the total global population. Anacapa is also the largest breeding colony of Western Gulls in the Channel Island and the second largest colony of Xantus?s Murrelets in the United States (Carter 1992).
San Miguel supports one third of the total breeding birds in the Channel Islands including 12 species and over 33,000 breeding birds (Wolf 2002; Carter 1992). While the majority are Brandt?s Cormorants, the island also hosts Ashy Storm-Petrels, Cassin?s Auklets, Xantus?s Murrelets, Least Storm-Petrels, Double-crested Cormorants, Pelagic Cormorants, Western Gulls, Pigeon Guillemots, Rhinoceros Auklets, and Tufted Puffin (Wolf 2002). San Miguel is the largest colony of Brandt?s Cormorants and one of the most important sites for Cassin?s Auklets (Wolf 2002; Channel Islands 2011).
Santa Barbara Island is home to 12 species of seabirds totaling 15,000 breeding birds (Carter 1992). This includes the largest United States colony of Xantus?s Murrelets, second largest colony of Brown Pelicans, and third largest colony of Ashy Storm-Petrels (Drost and Lewis 1995; Carter 1992).
Santa Cruz Island is home to 8 species and around 7,500 breeding birds including an important population of Ashy Storm-Petrel and Xantus?s Murrelet (Carter 1992). The islands also maintain 50% of the total breeding population of Ashy Storm-Petrels with a large population that nests in the caves and offshore rocks of Santa Cruz (Channel Islands 2011). Santa Cruz Island also has breeding Brant?s Cormorants, Cassin?s Auklets, Pelagic Cormorant, Pigeon Guillemot, and Western Gull (Carter 1992). Santa Catalina has Ashy Storm-petrel breeding offshore on rocks. It also has 50-150 breeding Xantus?s Murrelets. San Nicolas has large numbers of breeding Western Gull and Brandt?s Cormorant.

Ownership

All except Catalina are managed by the federal government, with San Nicolas operated as a U.S. Navy Base and the remaining five under Channel Islands National Park. The waters off the northern islands, San Miguel, Santa Rosa, Santa Cruz, Anacapa and Santa Barbara have also been recognized as one of three National Marine Sanctuaries (NOAA) in California. Nearly 90% of Catalina is owned by the non-profit Santa Catalina Island Conservancy, a conservation group, and it is the only island with a permanent town, Avalon. Both Santa Rosa and Santa Cruz have in-holdings of private land (large ranches) that pre-date their park designation.

Habitat

The Channel Islands North IBA is located in the Southern California Bight ecoregion and contains the following habitat types: open water and shrubland. The colony occupies a total land area of 209,933 hectares. All the Channel Islands have a Mediterranean climate that is characterized by cool, wet winters and hot dry summers. This climate is slightly milder than the mainland counterpart due to the marine influence, which creates milder summers, increased humidity and more fog. Average temperatures range from 53-39º F in the winter and between 62-70º F in the summer months. The island is largely frost free as temperatures rarely reach below freezing and the average humidity is around 60%. Heavy fog is very common and often blankets the whole island. When there is large amounts of fog temperatures rarely reach above 55º F (Channel Islands 2011). The habitat is very similar to that of Southern California with muted shrubs and rocky shores. Offshore the cold, nutrient rich waters from the north support diverse wildlife including productive kelp forests that occur of the southwest coast of the island (Channel Islands 2011; Satie 2003).