LC
Norfolk Island Gerygone Gerygone modesta



Taxonomy

Taxonomic source(s)
Christidis, L. and Boles, W.E. 2008. Systematics and Taxonomy of Australian Birds. CSIRO Publishing, Collingwood, Australia.
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2022 Least Concern
2016 Near Threatened D2
2013 Near Threatened D2
2012 Near Threatened D2
2008 Vulnerable D2
2004 Vulnerable
2000 Vulnerable
1996 Vulnerable
1994 Vulnerable
1988 Lower Risk/Least Concern
Species attributes

Migratory status not a migrant Forest dependency low
Land-mass type Average mass 8 g
Range

Estimate Data quality
Extent of Occurrence (breeding/resident) 72 km2 medium
Area of Occupancy (breeding/resident) 72 km2 good
Severely fragmented? no -
Population
Estimate Data quality Derivation Year of estimate
Population size 3800-8000, 5000 mature individuals poor estimated 2020
Population trend unknown medium - -
Generation length 2.95 years - - -
Number of subpopulations 1 - - -
Percentage of mature individuals in largest subpopulation 100% - - -

Population justification: Inside Norfolk Island National Park, 3,830 (95% CI 2,650-5,540) mature individuals were estimated in 2009 (Dutson 2013), followed by a higher estimate of 6,305 (95% CI 5,166-8,583) in October 2019. Following Nance et al. (2021), the population size of the whole island is therefore set to 3,800-8,000 mature individuals, with a best estimate of c.5,000.

Trend justification: Historically, c.1600 pairs were estimated to persist in 1988 and 1997 (Robinson 1988, 1997). A larger estimate was made in 2009, when 3,830 (95% CI 2,650-5,540) were thought to exist in the national park (Dutson 2013), while an even more recent estimate (6,305; 95% CI 5,166-8,583) from 2019 suggests the population may have increased further (Nance et al. 2021). However, each of these estimates was born from differences in survey technique, such that direct and robust comparisons are not possible. Nonetheless, a decline is considered very unlikely, and the species is probably increasing in abundance (Nance et al. 2021). 


Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
Norfolk Island (to Australia) extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Norfolk Island (to Australia) Norfolk Island

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Artificial/Terrestrial Pastureland suitable resident
Artificial/Terrestrial Rural Gardens suitable resident
Forest Subtropical/Tropical Moist Lowland major resident
Shrubland Subtropical/Tropical Moist major resident
Altitude 0 - 320 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops - Small-holder farming Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Negligible declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture Livestock farming & ranching - Small-holder grazing, ranching or farming Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Negligible declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Negligible declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Ongoing Minority (<50%) No decline Low Impact: 4
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus exulans Timing Scope Severity Impact
Ongoing Minority (<50%) No decline Low Impact: 4
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Rattus rattus Timing Scope Severity Impact
Ongoing Minority (<50%) No decline Low Impact: 4
Stresses
Reduced reproductive success
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Unspecified species Timing Scope Severity Impact
Future Whole (>90%) Unknown Unknown
Stresses
Species mortality

Recommended citation
BirdLife International (2024) Species factsheet: Gerygone modesta. Downloaded from https://datazone.birdlife.org/species/factsheet/norfolk-island-gerygone-gerygone-modesta on 28/02/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 28/02/2024.