Taxonomic note
Has frequently been considered a subspecies of H. unicolor or of H. ostralegus; differentiation relatively weak, and species status perhaps questionable. Recent study of mtDNA, however, supported treatment as a separate species (Banks and Paterson 2007). Form H. ostralegus finschi has on occasion been associated with present species. Monotypic.
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.
Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Critically Endangered | Endangered | Vulnerable |
---|---|---|
- | D | D1 |
Year | Category | Criteria |
---|---|---|
2022 | Endangered | D |
2016 | Endangered | D |
2012 | Endangered | D |
2008 | Endangered | D1 |
2006 | Endangered | |
2004 | Endangered | |
2000 | Endangered | |
1994 | Endangered | |
1988 | Threatened |
Migratory status | not a migrant | Forest dependency | does not normally occur in forest |
Land-mass type | Average mass | - |
Estimate | Data quality | |
---|---|---|
Extent of Occurrence (breeding/resident) | 2,800 km2 | medium |
Area of Occupancy (breeding/resident) | 24 km2 | medium |
Severely fragmented? | no | - |
Estimate | Data quality | Derivation | Year of estimate | |
---|---|---|---|---|
Population size | 200-249 mature individuals | good | estimated | 2021 |
Population trend | stable | medium | estimated | - |
Generation length | 11.46 years | - | - | - |
Number of subpopulations | 1 | - | - | - |
Percentage of mature individuals in largest subpopulation | 100% | - | - | - |
Population justification:
In 2014 a minimum of 309 birds were recorded in a census of the population, including about 110 pairs and overall 237 mature individuals (J.E. Dowding in litt. 2016). There were 228 mature individuals in 2019 and the population is considered to be stable (Robertson et al. 2021), therefore is placed in the band 200-249 mature individuals.
Trend justification: As a result of intensive predator management, stock exclusion and nest protection, the population rapidly increased by the mid-2000s to over 300 birds but is estimated to have remained fairly stable since (Moore and Dowding 2017, Robertson et al. 2021). In 1987-1988, the population was estimated at 100-110 birds, including 44 breeding pairs: eight on South East Island (Rangatira), 25 on Chatham Island, nine on Pitt Island and two on Mangere Island. In 1998, a census indicated 140-150 birds, representing a significant increase since 1987-1988. In 2004, a minimum of 266 birds were counted on most of the coast of these four islands in the Chathams group, representing a population of 310-340 birds (Moore 2005, 2007). The population appears to have levelled off as a result of less intensive management, having reached over 100 pairs and 310-360 individuals in total in 2006 (Moore 2008). A minimum of 309 birds were recorded in both 2010 and 2014, including c.110 pairs (Moore and Dowding 2017). The population has slightly decreased from 241 mature individuals in 2010, and 237 in 2014 to 228 in 2019, but is considered stable overall (Robertson et al. 2021). The population on Rangatira (which is not farmed and has no mammalian predators) has declined steadily from about 12 pairs in the 1970s to 2 pairs in 2016, for reasons that are not understood (Moore and Dowding 2017).
Country/Territory | Presence | Origin | Resident | Breeding visitor | Non-breeding visitor | Passage migrant |
---|---|---|---|---|---|---|
New Zealand | extant | native | yes |
Country/Territory | IBA Name |
---|---|
New Zealand | Main Chatham |
New Zealand | Mangere |
New Zealand | Rangatira South East Island |
New Zealand | Rangiauria Pitt Island |
Habitat (level 1) | Habitat (level 2) | Importance | Occurrence |
---|---|---|---|
Marine Intertidal | Rocky Shoreline | major | resident |
Marine Intertidal | Sandy Shoreline and/or Beaches, Sand Bars, Spits, Etc | suitable | resident |
Marine Intertidal | Shingle and/or Pebble Shoreline and/or Beaches | suitable | resident |
Marine Intertidal | Tidepools | major | resident |
Altitude | 0 - 200 m | Occasional altitudinal limits |
Threat (level 1) | Threat (level 2) | Impact and Stresses | |||||||
---|---|---|---|---|---|---|---|---|---|
Biological resource use | Hunting & trapping terrestrial animals - Intentional use (species is the target) | Timing | Scope | Severity | Impact | ||||
Past, Unlikely to Return | Minority (<50%) | Unknown | Past Impact | ||||||
|
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Climate change & severe weather | Habitat shifting & alteration | Timing | Scope | Severity | Impact | ||||
Future | Whole (>90%) | Unknown | Unknown | ||||||
|
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Climate change & severe weather | Storms & flooding | Timing | Scope | Severity | Impact | ||||
Ongoing | Majority (50-90%) | Negligible declines | Low Impact: 5 | ||||||
|
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Human intrusions & disturbance | Work & other activities | Timing | Scope | Severity | Impact | ||||
Ongoing | Majority (50-90%) | No decline | Low Impact: 5 | ||||||
|
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Invasive and other problematic species, genes & diseases | Invasive non-native/alien species/diseases - Ammophila arenaria | Timing | Scope | Severity | Impact | ||||
Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
|
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Invasive and other problematic species, genes & diseases | Invasive non-native/alien species/diseases - Bos taurus | Timing | Scope | Severity | Impact | ||||
Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
|
|||||||||
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 | ||||||
|
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Invasive and other problematic species, genes & diseases | Invasive non-native/alien species/diseases - Ovis aries | Timing | Scope | Severity | Impact | ||||
Ongoing | Minority (<50%) | No decline | Low Impact: 4 | ||||||
|
|||||||||
Invasive and other problematic species, genes & diseases | Invasive non-native/alien species/diseases - Rattus norvegicus | Timing | Scope | Severity | Impact | ||||
Ongoing | Majority (50-90%) | No decline | Low Impact: 5 | ||||||
|
|||||||||
Invasive and other problematic species, genes & diseases | Invasive non-native/alien species/diseases - Rattus rattus | Timing | Scope | Severity | Impact | ||||
Ongoing | Majority (50-90%) | No decline | Low Impact: 5 | ||||||
|
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Invasive and other problematic species, genes & diseases | Problematic native species/diseases - Gallirallus australis | Timing | Scope | Severity | Impact | ||||
Ongoing | Majority (50-90%) | No decline | Low Impact: 5 | ||||||
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Recommended citation
BirdLife International (2024) Species factsheet: Chatham Islands Oystercatcher Haematopus chathamensis. Downloaded from
https://datazone.birdlife.org/species/factsheet/chatham-islands-oystercatcher-haematopus-chathamensis on 24/12/2024.
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 24/12/2024.