• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic note
Zapornia atra (del Hoyo and Collar 2014) was previously placed in the genus Porzana.

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.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	D2

Red List history

Year	Category	Criteria
2022	Vulnerable	D2
2016	Vulnerable	D2
2012	Vulnerable	D2
2008	Vulnerable	D2
2004	Vulnerable
2000	Vulnerable
1996	Vulnerable
1994	Vulnerable
1988	Threatened

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	80 km2	medium
Area of Occupancy (breeding/resident)	80 km2
Number of locations	1	-
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	3800-8400, 5600 mature individuals	good	estimated	2015
Population trend	stable	medium	estimated	-
Generation length	3.29 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: A rat eradication attempt in 2011 reduced the population to probably <500 individuals, but because sufficient individuals were maintained in captivity during the eradication attempt, counts in 2013 and 2015 suggest that the population has largely recovered (S. Oppel and A. Bond in litt. 2016). In 2015, the total estimated abundance of Henderson Crakes (based on extrapolations from 25 point count stations and an assumed radius of origin of 100 m) was 8,513 birds (95% CI 5,755-12,749), equivalent to c.5,600 (3,800-8,400) mature individuals. These values are similar to estimations made (by different methods) of c.3,240 in 1987 and c.6,200 in 1992 (Graves 1992, Jones et al. 1995) indicating a fairly constant population over time.

Trend justification: Studies indicate that predation rates are low and reproduction rates are sufficient to replace birds lost. Estimated population sizes from 2015 (c.5,600 mature individuals) are similar to estimates made (by different methods) in 1987 (c.3240) and 1992 ([c.6,200] Graves 1992, Jones et al. 1995) indicating a fairly constant population over time.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Pitcairn Islands (to UK)	extant	native	yes

Country/Territory	IBA Name
Pitcairn Islands (to UK)	Henderson Island

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Altitude	0 - 40 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Unknown		Unknown
		Stresses Indirect ecosystem effects, Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus exulans	Timing		Scope		Severity		Impact
		Ongoing		Whole (>90%)		No decline		Medium Impact: 6
		Stresses Reduced reproductive success
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus norvegicus	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Rapid Declines		Medium Impact: 6
		Stresses Reduced reproductive success
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Rattus rattus	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Rapid Declines		Medium Impact: 6
		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
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Unspecified species	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Negligible declines		Low Impact: 4
		Stresses Ecosystem degradation

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Recommended citation
BirdLife International (2024) Species factsheet: Henderson Island Crake Zapornia atra. Downloaded from https://datazone.birdlife.org/species/factsheet/henderson-island-crake-zapornia-atra on 23/12/2024.
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 23/12/2024.