CR
Rapa Fruit-dove Ptilinopus huttoni



Justification

Justification of Red List Category
This species is classified as Critically Endangered because the population is extremely small and surveys have indicated that it is continuing to decline.

Population justification
A survey in 2017 estimated the population at 160 (145-243) individuals, based on counts and maps of forested areas produced in 1986, with the caveat that the maps appeared to underestimate the amount of forest present, so the population estimates may be underestimates (Blanvillain & Patira 2017, C. Blanvillain in litt. 2017). This equates to approximately 107 (97 - 162) mature individuals. Notwithstanding the figure potentially being an underestimate, it is likely that the total number of mature individuals is less than 250 and is here placed in the band 50-249 mature individuals.

Trend justification
The results of surveys carried out in 1989-90 (Thibault & Varney 1991) and 2017 (Blanvillain & Patira 2017) estimate a population reduction from 274 (175-368) individuals in 1990 to 160 (145-243) individuals in 2017. This equates to a reduction of 21% across the last ten years (assuming linear decline and extrapolating to 2018), placed here in the band 15-25%.

Distribution and population

This species is endemic to the tiny island of Rapa in the Tubuai Islands, French Polynesia, where its population was estimated at 160 (145-243) individuals in 2017 (Blanvillain & Patira 2017). A previous survey in 1990 produced an estimate of 274 individuals (175-368) (Thibault and Varney 1991), indicating that the population declined by 42% between the two surveys. It is probable that the area of available habitat has diminished during the 20th century and the quality of habitat has declined due to the introduction of the Chinese guava Psidium cattleianum (Blanvillain & Patira 2017).

Ecology

Although once thought to be confined to remaining undisturbed forest fragments in valleys and mountains between 40 and 450 m (292 ha in 1991), and not able to utilise coastal vegetation or secondary forest (Thibault and Varney 1991), it has been seen in pine plantations and may feed on the introduced Chinese guava Psidium cattleianum (P. Raust in litt. 2007). It feeds on fleshy fruit and nectar from flowers (Thibault and Varney 1991).

Threats

Destruction and degradation of forest by goats, cattle, fires (used to control fernland, increase grazing land or to facilitate hunting of pigs) and felling are the main threats (SPREP 2001, Meyer 2002). Very little of the island's original native forest cover remains (Meyer 2002). Predation by feral cats and Polynesian rat Rattus exulans are possible threats, while hunting for food by local inhabitants is no longer a threat owing to an improvement in the standard of living on the island (Thibault and Varney 1991). Plantations of Strawberry guava Psidium cattleianum are widespread and are not used by the species (Blanvillain & Patira 2017).

Conservation actions

Conservation and Research Actions Underway
Proposals have been made to protect the Hiri Valley and to consider captive breeding (Thibault and Varney 1991). In 2017, a project commenced which aimed to restore forest, control P. cattleianum and control grazing livestock (Hurrell 2017).

Conservation 
and Research Actions Proposed 
Monitor the population. Study the level of use of P. cattleianum and its impacts on occupancy and population trends. Control grazing with the use of fences and/or enclosures (Meyer 2002). Discuss with the local community the possibility of establishing a protected area in the upland forests - if agreement is reached, fence forest remnants to reduce grazing pressure (SPREP 1999). Reduce goat numbers (SPREP 1999). Exclude fires from upland areas (SPREP 1999). Consider the possibility of translocation to another island to establish a second population (SPREP 1999). Investigate the impact of cats and rats on the species, and take precautions to prevent invasion by black rat Rattus rattus. As a precaution, establish a captive population.

Identification

31 cm. Medium-sized, mostly green pigeon, larger and longer tailed than most fruit-doves. Feathers of lower chest cloven producing rows of shadows that appear as streaks. Pale blue-grey foreparts (head, neck, chest, upper back) shading into green of body above. Yellowish-white tip of tail, not sharply demarcated. Bright rose crown, face and throat, dark rose undertail-coverts. Yellow lower belly and edges of wing feathers. Rose-purple band below cloven chest feathers. Yellow bill and iris. Red legs. Voice Repetitive series of double oo-wa notes.

Acknowledgements

Text account compilers
Ashpole, J, Derhé, M., Mahood, S., O'Brien, A., Pilgrim, J., Stattersfield, A., Dutson, G., Wheatley, H.

Contributors
Blanvillain, C., Raust, P., Kesler, D., Millett, J.


Recommended citation
BirdLife International (2019) Species factsheet: Ptilinopus huttoni. Downloaded from http://www.birdlife.org on 15/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 15/11/2019.