serious harm to the local vegetation; pigs introduced in 1979 have caused harm to the local fauna. Native vertebrates – except birds – are limited to two snake species and one iguanid lizard species, both endemic. A few seabird species breed on Clarion or formerly did so. The island is near the north(east)ern limit of the breeding range of several of these, but their continued presence needs confirmation: Nazca booby, Sula granti East Pacific red-footed booby, Sula sula websteri – a doubtfully distinct subspecies East Pacific great frigatebird, Fregata minor ridgwayi – breeding suspected but not verified; a doubtfully distinct subspecies For reasons not fully known, Clarion seems to be more attractive to shorebirds and other vagrant or migrant birds than Socorro; perhaps this is due to the presence of red-tailed hawks on the latter island. Great blue heron, snowy egret, white-faced ibis, Pacific and possibly American golden plover, spotted sandpiper, wandering tattler, ruddy turnstone, black-necked stilt, western gull and barn swallow are examples of the species that can be encountered on Clarion with some regularity; most of the shorebirds congregate in the sheltered shallows of Sulphur Bay. Others, such as blue-winged teal, western sandpiper, least sandpiper, short-eared owl, belted kingfisher, northern mockingbird and brown-headed cowbird have only been recorded on very few occasions, sometimes only once. Endemic animals Clarion burrowing owl, Athene cunicularia rostrata Clarion wren, Troglodytes tanneri (vulnerable) Clarion mourning dove, Zenaida macroura clarionensis Clarion Island whipsnake, Masticophis anthonyi Urosaurus clarionensis Clarion nightsnake, Hypsiglena unaocularis In addition, the local population of the western raven (Corvus corax sinuatus or C. sinuatus) was formerly considered a distinct subspecies , but this is not usually accepted at present. It can be expected that this question will soon be resolved as there is currently renewed interest in the phylogeny of the common/western/Chihuahuan ravens. If the Revillagigedos population is indeed distinct, it might be endemic of Clarion as the only other local subpopulation, on San Benedicto, was destroyed by a volcanic eruption on August 1, 1952; on the other hand, mainland birds have sometimes been assigned to also. The Clarion population of the critically endangered Townsend's shearwater (Puffinus auricularis) was probably extirpated in 1988 due to the feral pigs' depredations on the young and nesting birds. Plants Endemic plant taxa of Clarion are: Aristida tenuifolia Ipomoea halierca Physalis clarionensis Brickellia peninsularis var. amphithalassaBulbostylis nesiotica, Cheilanthes peninsularis var. insularis, Cyperus duripes, Euphorbia anthonyi, Nicotiana