Protected Areas and World Heritage Programme

NAME Birnie Island Wildlife Sanctuary

LOCATION 3^o35'S, 171^o33'W; 90 km east of Phoenix (Rawaki) in the Phoenix Islands.

AREA 20 ha.

ALTITUDE Sea level to 4 m on the eastern beach crest.

OVERVIEW A small coral island with interesting vegetation cover, a landlocked supersaline lagoon and large breeding colonies of seabirds. The island has never been inhabited and is the least disturbed of the Phoenix Group.

PHYSICAL FEATURES Birnie Island, the smallest of the Phoenix Islands, is a low coral sandstone island measuring only 1.2 km by 0.5 km. A shallow, landlocked supersaline lagoon occupies a depression in the southeast. Despite being stream-fed, the lagoon often dries out completely. The northern half of the island is flat and covered in uniform vegetation. The east coast is rocky and consists of coral sandstone and coral fragments, while the west coast is low and sandy. Birnie is one of the drier Phoenix Islands, with an inferred mean annual rainfall of 600-800 mm or less. The prevailing winds are easterly trades.

ECOLOGICAL FEATURES The vegetation is extremely simple. Most of the island is covered by low herbs dominated by Portulaca lutea and some Boerhavia albiflora. These occur in pure stands or in varying co-dominant mosaics. The beach, beach crest and lagoon flats have either sparse or no vegetation cover, while the lagoon shoreline has an interrupted strip of uniform Sesuvium portulacastrum. This also occurs in a number of shallow depressions. Scattered dwarf Sida fallax scrub and bunch grass, probably Lepturus sp., have been recorded, but have since become locally extinct (Garnett, 1983).

LAND TENURE State owned.

CONSERVATION MEASURES TAKEN Birnie Island was declared a bird sanctuary in June 1938 under the Gilbert and Ellice Island Colony Wild Birds Protection Ordinance of 1938. The island was designated a Wildlife Sanctuary in 1975 under the 1975 Wildlife Conservation Ordinance.

CONSERVATION MEASURES PROPOSED Birnie was selected by the International Biological Programme as one of the "Pacific Ocean Islands Recommended for Designation as Islands for Science" (Elliott, 1973). Dahl (1980) proposed the establishment of a national or international reserve in the Phoenix Islands, including Birnie, McKean, Phoenix, Enderbury, Orona (Hull) and possibly also Manra (Sydney), with Kanton Island as the communications link and surveillance centre. Garnett (1983) has made a number of general recommendations for management of the Phoenix Islands, including erection of multi-lingual notice boards advising visitors, such as long-distance yachtsmen and fishermen from Japanese, Taiwanese and Korean fleets, of the importance of the islands for science and nature conservation. Garnett (1983) has also recommended that the Wildlife Sanctuary be upgraded to Closed Area.

LAND USE Uninhabited. The island was bonded under the 1856 American Guano Act in February 1860, and was formally placed under British protection in July 1889. The rights to exploit the island passed through a number of commercial concerns in the 19th and early 20th centuries, but no activities were undertaken. Colonization was considered in 1937, but not implemented, and an unsuccessful attempt was made to establish coconut plantations in 1939. Since then, the island has remained uninhabited, unused and seldom visited.

DISTURBANCES AND THREATS None known.

HYDROLOGICAL AND BIOPHYSICAL VALUES None known.

SOCIAL AND CULTURAL VALUES None known. The presence of Polynesian Rats suggests that Birnie was visited by Polynesians in pre-historic times, but there is no evidence that the island was ever settled.

NOTEWORTHY FAUNA Birnie is an important breeding site for seabirds; 22 species have been recorded and six are known to breed. Populations of 100 Brown Boobies (Sula leucogaster) and 100 Blue-grey Noddies (Procelsterna cerulea) are considered to be nationally important, whilst 350-800 Masked Boobies (Sula dactylatra) may be internationally important. Polynesian Rats (Rattus exulans) are common on the island, and Green Turtles (Chelonia mydas) nest on the beaches. Invertebrates are poorly known, but include a mite and two parasitic flies (Garnett, 1983).

NOTEWORTHY FLORA The undisturbed atoll vegetation is considered to be of international significance (Garnett, 1983).

SCIENTIFIC RESEARCH AND FACILITIES Few people have ever visited the island and only limited research has been undertaken.

MANAGEMENT AUTHORITY AND JURISDICTION Wildlife Conservation Unit, Ministry of Line and Phoenix Development.

REFERENCES Dahl (1980, 1986); Elliott (1973); Garnett (1983); IUCN (1991); TCSP (1990).

REASONS FOR INCLUSION 1a, 2c. The least disturbed (most natural) of the Phoenix Islands, valued for its vegetation, supersaline lagoon, seabird colonies and turtle population.

SOURCE See references.