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Ptilinopus insularis 

Scope: Global
Language: English
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_onStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Columbiformes Columbidae

Scientific Name: Ptilinopus insularis (North, 1908)
Common Name(s):
English Henderson Fruit-dove, Henderson Island Fruit-Dove, Scarlet-capped Fruit Dove
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
Identification information: 22 cm. Small, basically two-toned pigeon. Crown and forehead bright rose-red narrowly bordered by golden-yellow. Pale blue-grey head, neck, upper back, and chest. Rest of body olive-green, paler below with yellow undertail-coverts. Tail with bronzy reflections above, tipped white. Wing feathers edged yellow, tending to white on tertials. Yellow-green bill. Orange-red iris and feet. Voice A coarse coo.

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Brooke, M., Bell, B., Hall, J., Bond, A. & Oppel, S.
Facilitator/Compiler(s): Derhé, M., Mahood, S., Shutes, S., Stattersfield, A. & Stringer, C.
Justification:
This species qualifies as Vulnerable as it is only found on one small island where it remains at risk from the accidental introduction of exotic species.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Ptilinopus insularis is confined to Henderson in the Pitcairn Islands (to UK), a small uninhabited, raised-reef island in the south-central Pacific Ocean.

Countries occurrence:
Native:
Pitcairn
Additional data:
Estimated area of occupancy (AOO) - km2:43Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:46
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:In 1987, its population was estimated at c.3,420 birds (Graves 1992; adjusted to 3070 individuals using the correct island area, and assuming 75% habitat suitability; Brooke & Jones 1995) and, in 1992, using a different technique, at c.3150 (adjusted to 3650 using correct island area); in 2003 there appeared to be no major change in the species' abundance (Brooke and Jones 1995, M. Brooke in litt. 2007). In 2015, the population at 25 point count locations was estimated to number 245 (95% CI 195 - 327) 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 (Oppel and Bond in litt. 2016). The trend estimated for counts from 2009 - 2015 indicated that the species was slightly increasing (mean trend 0.074, 95%CI: 0.041 - 0.106). Numbers may be limited by food supply (Brooke and Jones 1995) and are assumed to be slightly increasing following the failed eradication of Pacific rats Rattus exulans in 2011 (Oppel and Bond in litt. 2016).

Trend Justification:  No new data are available, but the species's entire range is well protected and no new threats are suspected.
Current Population Trend:Increasing
Additional data:
Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:The species inhabits interior forest, with dense understorey. It is a specialist frugivore (possibly territorial so that it can exploit fruits as they become available), foraging solitarily or in pairs (Brooke and Jones 1995). Research in 1991/1992 recorded 19 different plants in its diet, with Procris pedunculata constituting the major food. A preference for fruit with a high water content suggests that the species may rely on its food for obtaining water, especially during dry spells (as there is no permanent water on Henderson) (Brooke and Jones 1995). From two nests, each with a single egg recorded in March, the breeding season would appear to be at the beginning of the calendar year and clutch-size is probably one (Brooke and Jones 1995).

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):3.2
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): The species appears little affected by the presence of Pacific rat Rattus exulans. In August 2011, an operation was carried out attempting to eradicate R. exulans from Henderson Island. This operation failed and rat density returned to pre-eradication levels by 2013 (Churchyard et al. 2013). However, P. insularis numbers were seemingly unaffected based on counts in 2015 (Oppel and Bond in litt. 2016). 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 too. Pacific rats do suppress seedling germination and growth on Henderson, which could be limiting P. insularis populations (A. Bond in litt. 2015).


Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
In 1988, Henderson was designated a World Heritage Site. Following a feasibility study (Brooke and Towns 2008) a rat eradication operation was attempted on Henderson Island in August 2011, but this 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.


Citation: BirdLife International. 2016. Ptilinopus insularis. The IUCN Red List of Threatened Species 2016: e.T22691490A93314387. . Downloaded on 24 October 2017.
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