CR
Rapa Shearwater Puffinus myrtae



Taxonomy

Taxonomic note

Puffinus newelli (del Hoyo and Collar 2014) has been split into P. newelli and P. myrtae (Handbook of the Birds of the World and BirdLife International 2018). Martínez-Gómez et al. (2015) found that P. (n). myrtae, ‘Rapa Shearwater’, is genetically more distinct from newelli than newelli is from auricularis. On this basis they propose that myrtae be treated as a full species. Such an arrangement is supported by Shirihai et al. (2017), who noted:

'Rapa Shearwater is much smaller (in all biometric characters) than the other two taxa…, and is furthermore highly distinctive in having a unique combination of white undertail-coverts (vs. dark in both newelli and auricularis) and whitish inner webs to the remiges, as well as a white face.'

Following revised scoring of parsed characters for the differentiation of P. auricularis, P. newelli and P. myrtae, the latter emerges as a very strong candidate for species rank, given that the effect size for wing length vs the smaller of the other two taxa (auricularis), based on Table 3 in Shirihai et al. (2017), is –6.56 (score 3); white vs dark undertail-coverts (at least 2); whitish inner webs to the remiges (at least 1); and a ‘white face’ (impossible to interpret, and in fact not apparent in several photographs online).

We will seek to confirm the characters identified as distinctive by Shirihai et al. (2017) but accept the strong likelihood of at least minor vocal differentiation. Allowing 1 for such an eventuality, and having a score of 6 already on morphological grounds, we tentatively accord myrtae species status as Rapa Shearwater.

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.
Handbook of the Birds of the World and BirdLife International. 2018. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 3. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v3_Nov18.zip.
Martínez-Gómez, J. E., Matías-Ferrer, N., Sehgal, R. N. M. & Escalante, P. 2015. Phylogenetic placement of the critically endangered Townsend’s Shearwater (Puffinus auricularis auricularis): evidence for its conspecific status with Newell’s Shearwater (Puffinus a. newelli) and a mismatch between genetic and phenotypic differentiation. J. Orn. 156: 1025-1034.
Shirihai, H., Schweizer, M., Kirwan, G. M. & Bretagnolle, V. 2017. The type of Rapa Shearwater Puffinus (newelli?) myrtae from the Austral Islands, Polynesia, with remarks on the morphological variation of the taxon. Bull. Brit. Orn. Club 137: 127-134.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
C2a(ii) B2ab(iii,v); C2a(i,ii); D B2ab(iii,v); C2a(i,ii); D1+2

Red List history
Year Category Criteria
2018 Critically Endangered C2a(ii)
2016 Not Recognised
2012 Not Recognised
2008 Not Recognised
2004 Not Recognised
2000 Not Recognised
1994 Not Recognised
1988 Not Recognised
Species attributes

Migratory status full migrant Forest dependency medium
Land-mass type Average mass -
Range

Estimate Data quality
Extent of Occurrence (breeding/resident) 126,000 km2 medium
Area of Occupancy (breeding/resident) 1 km2 medium
Number of locations 4 -
Severely fragmented? no -
Population
Estimate Data quality Derivation Year of estimate
Population size 50-249 mature individuals medium estimated 2018
Population trend decreasing medium estimated 1964-2010
Generation length 15.5 years - - -
Number of subpopulations 1 - - -
Percentage of mature individuals in largest subpopulation 100% - - -

Population justification: In 1974 the population size was estimated at 265-380 pairs (excluding any potential birds breeding on the main Rapa Island), but no individuals were located during surveys in 1989 (Thibault and Varney 1991). A survey of Morotiri found no individuals of this taxon (Gaskin et al. 2006), and a visit to Rapa in 2017 found only a very small number of individuals (though this was likely not during the breeding season) (S. Cranwell per M. O’Brien in litt. 2018). At sea surveys find the occasional individual, but it appears highly unlikely that there 500-800 mature individuals remaining (M. O’Brien in litt. 2018). The population size is tentatively placed in the band 50-249 mature individuals, equating to 75-375 individuals in total, although it potentially could be lower than this.

Trend justification:

While it is likely that the threats this species faces are causing declines, there is no clear evidence of the rate of decline.


Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
French Polynesia extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
French Polynesia Ilots rocheux de Rapa et Marotiri

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Moist Montane major breeding
Grassland Subtropical/Tropical High Altitude suitable breeding
Marine Neritic Pelagic major non-breeding
Marine Neritic Pelagic major breeding
Marine Oceanic Epipelagic (0-200m) major non-breeding
Marine Oceanic Epipelagic (0-200m) major breeding
Altitude   Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Livestock farming & ranching - Small-holder grazing, ranching or farming Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Hunting & trapping terrestrial animals - Intentional use (species is the target) Timing Scope Severity Impact
Past, Unlikely to Return Minority (<50%) Slow, Significant Declines Past Impact
Stresses
Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Capra hircus Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Past, Unlikely to Return Whole (>90%) Rapid Declines Past Impact
Stresses
Reduced reproductive success, Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus exulans Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Reduced reproductive success

Recommended citation
BirdLife International (2024) Species factsheet: Rapa Shearwater Puffinus myrtae. Downloaded from https://datazone.birdlife.org/species/factsheet/rapa-shearwater-puffinus-myrtae on 08/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 08/12/2024.