Rapa Fruit-dove (Ptilinopus huttoni) (BirdLife species factsheet) is currently classified as Vulnerable because the population is very small and confined to undisturbed forest fragments on one tiny island.
P. huttoni is endemic to the island of Rapa in the Tubuai Islands, French Polynesia, which has an area of approximately 40km2. The species has previously been considered to be restricted to undisturbed forest fragments in valleys and mountains between 40m and 450m, of which there were 292ha in 1991 (Thibault & Varney 1991). However, it has also been seen in pine plantations and may feed on the introduced Chinese guava Psidium cattleianum (P. Raust in litt. 2007).
In 1991 a survey of P. huttoni estimated the total population as 274 individuals based on the average population density ascertained through point counts multiplied by the total area of forest on Rapa (Thibault & Varney 1991). Based on this population estimate, together with the species’ restricted range on a single island with a plausible future threat that could cause a very rapid future decline, P. huttoni is currently listed as Vulnerable under criteria D1 and D2.
The population appears to be stable and the 1991 survey concluded that there had been no serious decline since 1974 (Thibault & Varney 1991). Nevertheless, it is probable that the area of available habitat has diminished during the 20th century and a 2001 report noted that Rapa is overgrazed by about 6,000 goats and 600 cattle (SPREP 2001). The introduction of P. cattleianum may have provided an additional food source and boosted the population of P. huttoni, but surveys are needed to confirm this (P. Raust in litt. 2007).
Based on the total population estimated of 274 individuals, the number of mature individuals may approximate c.180. This meets the threshold for listing the species as Endangered under criterion D (250 mature individuals). It is therefore proposed that P. huttoni is uplisted to Endangered.
Additional information on the current P. huttoni population and trend and further comments on this proposal are welcomed.
SPREP 2001. Polynesia workshop, Rarotonga, 26-30 April 1999. Priorities and a Draft Avifauna Conservation Strategy for the Pacific Islands Region. In Sherley, G. (Ed.), Bird conservation priorities and a draft avifauna conservation strategy for the Pacific Islands Region (pp. 1-9). South Pacific Regional Environment Program.
Thibault, J. C., & Varney, A. (1991). Numbers and habitat of the Rapa Fruit-dove Ptilinopus huttoni. Bird Conservation International, 1(01), 75-81.