The Introduced and Native Terrestrial Vertebrates of Fiji

A complete list of native and introduced Fijian terrestrial vertebrates has been compiled that includes a number of previously unrecorded reptiles. An analysis has been made of the habitat distribution of most species. The past and present status of the various native vertebrates is examined, and the impact of post-European vertebrate introductions on the indigenous and endemic fauna is assessed in the light of current knowledge. It is concluded that the success ofcertain introduced bird species is due in part to their close association with human-modified habitats, while the native species are primarily adapted to a forest environment. Although the introduced mongoose may be implicated in the decline of some native vertebrate species, its effect may be less important than previously stated and is certainly less than the effect of native habitat destruction and environmental modification by humans. NUMEROUS STATEMENTS MAY BE FOUND in the literature concerning the effect of introduced plant and animal species on the native communities found on Pacific islands (Berger 1972, Guppy 1906, Thaman 1974, Williams 1953). The bulk of such comments refer to deleterious effects in terms of causing reduction in numbers of native species; or the elimination of such species from certain habitats, areas, or islands through competitive exclusion (Mercer 1964, Parham 1956, Thaman 1974, Watson 1960, Wood and Wetmore 1925); or direct mortality due to introduced predators (Brewster 1935, Gorman 1972, 1975a, b, Mercer 1964). In contrast, Lack (1975) suggests that the introduced land birds of Jamaica have had no direct or indirect competitive effect on the native species and that the successful establishment of certain post-European bird introI This work was supported in part by a grant from the University of the South Pacific to John C. Pernetta and in part by a grant from the British Ornithologists' Union to Dick Watling. Manuscript accepted 28 June 1978. 2 University of the South Pacific, School of Natural Resources, P.O. Box 1168, Suva, Fiji. Present address of Pernetta: University of Papua New Guinea, Department of Biology, Box 4820 University P.O. , Port Moresby, Papua New Guinea. Present address of Watling: University of Cambridge, Department of Applied Biology, Pembroke Street, Cambridge, CB2 3DX, England. ductions results from their close association with people. The purpose of the present paper is to assess the extent of the interaction between introduced and native species of terrestrial vertebrates in Fiji. It is based upon an extensive review of the often anecdotal literature, together with 9 years of observational data on birds (D. W.) and the extensive collection and observation of reptiles, amphibia, and mammals by both authors on various islands of the Fiji group. THE FIJI ISLAND GROUP The Fiji group consists of approximately 320 islands located between 16° and 20° S, 177° W, and 175° E. The land area totals 18,270 km2 , the bulk of which forms two major islands, Viti Levu and Vanua Levu (Figure 1). Southwest tradewinds blow steadily from September to April, resulting in a hot, wet summer and a drier, cooler winter. Mean monthly temperatures range from 23°C in July and August, to 27°C in January; humidity ranges from 75% during winter to 88% in summer (Fiji Weather Bureau statistics). The geological history of the islands indicates that Viti Levu consists of an Eocene