Vatu-i-Ra is a small island approximately 100m by 300m wide, comprising two small hills connected by a narrow neck. The higher north-east side and each end of the island are composed of volcanic rock. The rest of the islands consists of flat coral sand, not far above spring high tide level.
Vatu-i-Ra is one of the most regularly monitored sites in Fiji with data available from over 15 survey visits extending back to 1963.
The island qualifies as an IBA owing to its internationally significant population of Black Noddy. It can be difficult to compare between survey years as different methods have been used to count seabird populations. Counts of apparently occupied nests were lower in 1963 (1500 estimated by Morris) and 1974 (4550 - Tarburton 1978) than in recent years with total nest counts of c.26,000 in 2003 (BirdLife International 2003), c.29,000 in 2008 (Roneil et al. 2008) and c.21,000 in 2011 (BirdLife International, unpublished data). However, estimates of the number of adults during regular visits between 1974 and 1981 based on mark-recapture extrapolations from a banded sample of birds fluctuate between 10,865 and 58,203 (Tarburton 1987). These estimates are roughly comparable with total population estimates we can derive from the number of apparently occupied nests between 2003 and 2011 (based on a ratio of 1 nest: 3 adults including non-breeding birds). Elsewhere, Black Noddy populations show considerable within-season, inter-annual and decadal population fluctuations (Congdon et al. 2007), so it is not yet possible to detect long-term population trends, or to definitively say whether the removal of rats from the island is allowing a population increase. As a tree-nesting species Black Noddy is not highly susceptible to egg-predation by rats.
While Black Noddies from Vatu-i-Ra have been shown to disperse as far as the Solomon Islands during the non-breeding season (Tarburton 1987), the species is predominantly sedentary, often roosting within breeding colonies during the non-breeding season, and it is considered a principally near-shore species (BirdLife International Foraging Range Database). The site also supports key populations of a number of other seabird species. Estimates of the number of breeding seabirds have remained relatively constant with: Red-footed Booby - 300–500 nests in 1963 (Morris undated), 400 nests in 1974 (Tarburton 1978), 400 individuals in 2003 (BirdLife International 2003), 600 individuals in 2006 (Environment Consultants 2006), 500 individuals in 2007 (Nature Fiji-Mareqeti Viti 2007) and 500 individuals in 2010 (Rosenstein 2010); Lesser Frigatebird - 500–700 pairs in 1963, 250 pairs in 1974, 150–250 non-breeders in 2003, >500 in 2008 (Morris undated; Tarburton 1978; Roneil et al. 2008); Brown Noddy - 80 pairs in 1970s, 50–100 pairs in 2003 (Tarburton 1986; BirdLife International 2003); White-tailed Tropicbird - one pair in 1974, one bird seen in 2003 (Tarburton 1978; BirdLife International 2003); and Black-naped Tern - 20-115 birds recorded over the period.
No firm conclusions can be drawn yet, but there is some evidence of increased nesting in recent years of some ground-nesting species, those most likely to suffer egg-predation by rats. These include Bridled Tern - 14 pairs in 1974, 200 pairs in 2003 and >500 adults in 2011 (Tarburton 1986; BirdLife International 2003; BirdLife International unpublished data, 2011); Brown Booby - no historic breeding recorded but small numbers of nests from 2006 onwards and up to 150 adults counted after 2006 (Environment Consultants 2006; Nature Fiji-Mareqeti Viti 2007); and Crested Tern - recorded in very low numbers historically before counts increased post 2003 to 120 in 2008 and with the first breeding record of 250 pairs in 2011 (Roneil et al. 2008; Bird 2011).
Other species breeding on Vatu-i-Ra is the Eastern Reef Heron (1 pair in 1974; 2 birds in 2003) and possibly Polynesian Starling (BirdLife International unpublished data); and some migrants visit including shorebirds and Barn Owl.
Non-bird biodiversity: Turtles have been reported to nest on the beach. An endemic skink, Pygmy Snake-eyed Skink, also occurs on Vatu-i-Ra.
Pressure/threats to key biodiversity
The major threat to the island's avifauna is the introduction of alien invasive species to the site. Human disturbance by fishers and tourists on diving trips could disrupt seabird breeding, particularly of ground-nesting species. Opportunistic harvest of chicks and eggs for food represents a potential threat.
Conservation responses/actions for key biodiversity
Vatu-i-Ra island after being identified as an IBA became the first island in Fiji to have invasive rodents (Pacific Rats) successfully removed. The community that has ownership over Vatu-i-Ra approached Birdlife for assistance to manage the island in early 2006. Birdlife Fiji Programme with support from the Critical Ecosystem Partnership Fund (CEPF), moved to eradicate rats and implement abatement procedures as a first step to support the community in managing the island sustainably. In February 2012 an acoustic playback device and 20 artificial petrel burrows have been installed to attract threatened burrow-nesting petrels to breed at the site enhancing its biodiversity importance.
The site meets the Ramsar criteria owing to its internationally significant waterbird population, so efforts should be made to facilitate its formal designation.
Unprotected. Site of National Significance. The site meets the Ramsar criteria owing to its internationally significant waterbird population.
Habitat and land use
Most of the islands is covered by vegetation, with taller Pisonia trees in the centre and on the outside shorter shrub-like trees (possibly Hibiscus tiliaceus). Several exposed areas, including one slope of the main hill at the southern end of the island become covered with couch-grass after sufficient rain (Tarburton 1978).
The island is uninhabited but is regularly visited by fishers and occasional tourists on dive trips. The island is under the Native Tenure and is owned by the Nagilogilo clan.
BirdLife International (2019) Important Bird Areas factsheet: Vatu-i-Ra. Downloaded from
http://www.birdlife.org on 13/11/2019.