San Clemente Island, the southernmost of the Channel Islands, is unique in that it was never connected to the mainland via a landbridge like its northerly sisters. Thus, its plant and animal communities evolved in near total isolation, supplemented by whatever drifted west in the sea or air. Its 50,000 acres are currently a mix of arid, cactus-rich scrub interspersed with a mix of exotic annual and native perennial (bunchgrass) grassland. The island is scored by numerous deep canyons (wet only briefly, in mid-winter) that extend from a long, central ridge to the sea, and support clumps of native trees and shrubs at seeps, including Toyon, Lemonadeberry and Island Cherry. Scattered oak groves (of endemic species) cling to the highest ridges. Until the 1980s, San Clemente was nearly destroyed by feral goats, which had been brought decades earlier and had reproduced to overrun the island, converting what was probably native maritime scrub into a dusty moonscape. An ambitious goat eradication program gained success through the late 1980s and by 2000, the vegetation still shows signs of recovery each year. At the time of this writing, all but a handful of goats have been eliminated.
(Note: Island was mapped with a 1-mile buffer)
San Clemente Island is best known for supporting a rare race (taxonomy of current population in dispute) of Loggerhead Shrike, notable for its minute population (c. 60 birds in 2001, fide N. Warnock, PRBO), wily temperament and affinity for rocky, inaccessible canyon edges. The conservation of this bird, which includes a captive breeding program, has become a small industry involving dozens of biologists. Other SCI endemics include races of Sage Sparrow, nearly as rare, and Channel Island races of Spotted Towhee and Song Sparrow that are now apparently extinct (P. Collins, unpubl. data). Xantus' Murrelet apparently maintains a tiny population here, with nests known from Seal Cove and Bird Rock (Carter et al. 1992). The grassland habitat on San Clemente supports large numbers of Burrowing Owls in fall and winter likely the largest concentration in southern California away from the Imperial Valley. Snowy Plover has bred irregularly in very small numbers (single nests found), but an estimated 30-40 birds winter on the island (B. Foster, unpubl. data).Go to(http://www.prbo.org/cms/index.php?mid=162) for more information on PRBO's research with San Clemente Island Loggerhead Shrike.
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San Clemente Island has one of the most well-funded wildlife management programs in California, but one surprisingly dependent on Navy-biologist relations, often tested at this remote outpost. Examples of vexing problems include Navy personnel's feeding of a large feral cat population, which in turn prey on rare nesting birds. Thus, the island, home to the "rarest of the rare" of California's flora and fauna remains a major testing ground for bombs as well for endangered species recovery efforts.
The entire island is owned by the Navy, Department of Defense.
Presently, the dominant plant community on the island consists of native and non-native grasses that cover approximately 45% of the mainly flatter upper reaches of the island. Shrubs and trees on the island are mainly found in the canyons, and dominant species include: Lemonade Berry, Catalina Ironwood, Island Cherry oaks, Toyon., and coastal sagebrush. Native vegetation including Prickly-pear Cholla, bunchgrass, and velvet cactus are species commonly found on the terraces of the island, especially on the west side.