size, and large clutches, and demonstrating a low 

 reproductive potential. 



MANAGEMENT AND CONSERVATION 



The greatest threats to this lizard are preda- 

 tion and habitat destruction from introduction 

 of exotic species into these fragile island eco- 

 systems. Bezy (1976) notes that feral goats could 

 have a serious impact on this partially herbivorous 

 lizard and its habitat. He also notes that feral pigs 

 and cats undoubtedly feed on the lizard to some 

 extent. 



There is evidence of predation by feral house- 

 cats on X. riversiana on San Clemente Island, but 

 the magnitude of this loss has not been determined. 

 A feral-cat removal program is being planned for 

 San Nicolas Island (Steele 1979). The Cahfomia 

 Department of Fish and Game and the U.S. Navy 

 are currently considering a removal program for 

 some feral animals on San Clemente Island. The 

 Navy has a program for the control of feral goats, 

 but it is currently inactive (Federal Register 42, 

 No. 155). 



The alligator lizard [Gerrhonotus multicarin- 

 atus) has been accidentally introduced on San 

 Nicolas Island. Bezy (1976) feels that this lizard 

 may be a competitor with X. riversiana. G. multi- 

 carinatus and X. riversiana have exclusive distribu- 

 tions on the California Channel Islands (Savage 

 1967), which suggests that alligator lizards may 

 displace the smaller-sized island night lizard. 



AUTHORITIES 



Robert L. Bezy 

 Section of Herpetology 

 Natural History Museum 

 Los Angelos, California 90007 



John M. Brode 



California Department of Fish and Game 



1701 Nimbus Road 



Rancho Cordova, California 95670 



PREPARER'S COMMENTS 



Bezy (1972, 1976) indicated that there is 

 moderate morphological differentiation between 

 the three island populations of X. riversiana. 

 Variation within the species needs further study. 



The impact of predation by feral animals on 



San Clemente and San Nicolas Island populations 

 of X. riversiana, and the potential competitive 

 impact by Gerrhonotus multicarinatus on San 

 Nicolas Island populations are both in need of 

 immediate investigation. Control of these intro- 

 duced animals may be critical to the survival of 

 the endemic island night lizard. Remaining habi- 

 tat on San Nicolas and Santa Barbara Islands 

 should be protected from further decimation. 



LITERATURE CITED/ SELECTED 

 REFERENCES 



Bezy, R. L. 1972. Karyotypic variation and 

 evolution of the lizards in the family 

 Xantusidae. Los Angelos Nat. Hist. Mus., 

 Contri. Sci., 227: 1-29. 



-. 1976. Letter in response to federal pro- 

 posal of threatened or endangered status 

 for Klauberina riversiana. (42 FR 155: 

 40682-40683. 



Brattstrom, B. H. 1952. The food habits of 

 the night lizard, genus Xantusia. Copeia 

 1952(2):168-172. 



Goldberg, S. R. and R. L. Bezy. 1974. Repro- 

 duction in the island night lizard, Xantu- 

 sia riversiana. Herpetologica 30:350-360. 



Savage, J. M. 1957. Studies on the lizard family 

 Xantusiidae. III. A new genus for Xantu- 

 sia riversiana Cope, 1883. Zoologica 42: 

 82-86. 



-. 1967. Evolution of the insular herpeto- 

 fauna. Pages 219-227 in Philbrick, R. N. 

 (ed.) Proceedings of the Symposium on 

 the Biology of the California Islands. 363 

 pp. 



Schwenkmeyer, R. C. 1949. Food habits of 

 the island night lizard, Xantusia riversiana 

 reticulata, from San Clemente Island. Nat. 

 Hist. Misc. 38:1-3. 



Stebbins, R. C. 1954. Amphibians and reptiles 

 of western North America. McGraw-Hill, 

 New York. 537 pp. 



•. 1966. A field guide to the western rep- 

 tiles and amphibians. Houghton Mifflin, 



