VU
Henderson Lorikeet Vini stepheni



Justification

Justification of Red List Category
This species may prove to be the only member of its genus whose habitat and population size have been little affected by adverse changes to its environment. However, it qualifies as Vulnerable as it is found only on one small island, where it is at risk from the accidental introduction of alien species.

Population justification
The population is was estimated to number 720-1,820 individuals in 1987, roughly equating to 480-1,200 mature individuals (adjusted to 650-1600 individuals when using the correct island area and assuming 75% of the island is suitable habitat) (Oppel and Bond in litt. 2016). In 2015, the population at 25 point count locations was estimated to number 139 (95% CI 66 - 342) individuals. However, given the potentially long movements of this species it is difficult to extrapolate this sample from a limited (but unknown) area to a global population estimate. The trend estimated for counts from 2009 - 2015 indicated that the population is stable (mean trend 0.045, 95%CI: -0.017 - 0.107) (Oppel and Bond in litt. 2016).

Trend justification
Although no new data are available on population trends, the entire range of the species is well protected and no new threats are suspected. Hence, the species is suspected to be stable.

Distribution and population

Vini stepheni is restricted to Henderson in the Pitcairn Islands (to UK), a small uninhabited, raised-reef island in the south-central Pacific Ocean. 

Ecology

It occurs in native forest (often observed at the forest edge), and in coconut palms along beaches. It is a generalist feeder, consuming nectar, pollen and fruit from a wide variety of plants from beach-level to the plateau, although flowers from the plants Scaevola sericea and Timonius polygamus provide the main sources of nectar (Trevelyan 1995). Arthropods form part of the diet, including lepidopteran larvae found in the sporangia of the fern Phymatosorus (Trevelyan 1995).

Threats

This species appears little affected by the only introduced predator, Pacific rat Rattus exulans (Trevelyan 1995). In August 2011, a rat eradication operation was attempted on Henderson Island to eradicate R. exulans from the island but the attempt failed and rat density returned to pre-eradication levels by 2013 (Churchyard et al. 2013). However, the accidental introduction of a more aggressive predator, such as another Rattus species, could be devastating, and introduced diseases such as avian malaria and pox are another potential threat. The introduction of exotic plant species could have serious consequences for the native vegetation (Waldren et al. 1995) and therefore for this species.

Conservation actions

Conservation Actions Underway
CITES Appendix II. In 1988, Henderson was designated a World Heritage Site. Following a feasibility study (Brooke and Towns 2008) a rat eradication operation was carried out on Henderson island in August 2011  In August 2011, a rat eradication operation was attempted on Henderson Island to eradicate R. exulans from the island but the attempt failed and rat density returned to pre-eradication levels by 2013 (Churchyard et al. 2013).

Conservation Actions Proposed
Periodically resurvey to monitor numbers and trends. Ensure that further alien species are not accidentally introduced to Henderson. Re-attempt the eradication of Pacific rats from Henderson. 

Identification

18 cm. Red-and-green parakeet. Dark green above shading to golden-yellow tip of tail. Red on cheeks and underparts, dark purple central belly. Belt across chest green at sides, purple in centre. Golden-yellow bill and eyes. Voice A shrill screech.

Acknowledgements

Text account compilers
Mahood, S., Shutes, S., Stattersfield, A., Derhé, M. & Stringer, C.

Contributors
Brooke, M., Hall, J., Bell, B., Bond, A. & Oppel, S.


Recommended citation
BirdLife International (2019) Species factsheet: Vini stepheni. Downloaded from http://www.birdlife.org on 19/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/08/2019.