This species is listed as Endangered because it has an extremely small population. It has significantly increased over the last 20 years, probably owing to intensive conservation efforts. However, even on islands free from mammalian predators, population sizes fluctuate, with numbers on one island undergoing a possible long-term decline.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Haematopus unicolor (Sibley and Monroe 1990, 1993) has been split into H. unicolor and H. chathamensis following Turbott (1990).
Distribution and populationHaematopus chathamensis
48 cm. Black-and-white wader with short, thick legs. Black head, neck, upperparts, upper breast. White underparts with smudgy border on chest. Long, thick red bill. Orange eye-ring. Pink legs. Similar spp. Infrequent straggler Pied Oystercatcher H. longirostris has sharper border between black upperparts and white underparts on lower chest, longer bill, finer legs, feet.
is endemic to the Chatham Islands, New Zealand
. 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. Numbers on South East, however, appear to have gradually declined since the 1970s (Schmechel and O'Connor 1999). Very small numbers may breed on Star Keys (Heather and Robertson 1997). In 2004, a minimum of 266 birds were counted on most of the coast of four islands in the Chathams group, representing a population of 310-340 birds, including 89 pairs (Moore 2005, 2007). The population is thought to have levelled off at over 100 pairs, and 310-360 individuals, since 2006 (Moore 2008). The population on Chatham Island is thought to have reached carrying capacity, with 45 pairs monitored in 2009. Elsewhere at this time, 12 pairs were monitored on Pitt, three on South East and three on Mangere (Waugh 2009).Population justification
In 2004, a minimum of 266 birds were counted on most of the coast of four islands in the Chathams group, represented a population of 310-325 birds. By 2006 this had risen to 310-360 individuals. However, the number of mature individuals in breeding pairs remains below 250, and so the population is placed in the band 50-249 mature individuals.Trend justification
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 four islands in the Chathams group, representing a population of 310-340 birds (Moore 2005, 2007). The population appears to have levelled off, having reached over 100 pairs and 310-360 individuals in total in 2006 (Moore 2008). The population, therefore, is estimated to have remained fairly stable over the last 10 years, having increased very rapidly in the 10 preceding years.Ecology
It builds nests in scrapes on sandy and rocky shores, away from the waterline. Occasionally, it breeds amongst low vegetation or constructs nests out of vegetation (F. A. Schmechel in litt.
1999). It lays two to three eggs, usually in a simple scrape in sand or shingle (Heather and Robertson 1997, Moore 2009). It starts breeding from three years old and most pairs attempt breeding each season (98%); productivity averages 0.44 fledglings/season/pair (Schmechel and Paterson 2005). Mean life expectancy is 7.7 years. The oldest recorded bird lived for a minimum of 28 years (F. A. Schmechel in litt.
1999). It feeds principally on molluscs and marine worms, also taking other invertebrates, by probing and hammering with its bill (Heather and Robertson 1997, Moore 2009). Threats
Introduced predators are a major threat on Pitt and Chatham, as are cattle and sheep (B. D. Bell in litt.
1999, F. A. Schmechel in litt.
1999). South East and Mangere are free of mammalian predators, but population sizes are still highly variable, and the reason for the decline on South East is unknown (Schmechel and O'Connor 1999). However, video cameras set by nests have revealed that feral cats are a major nest predator (Moore 2005). Predation by native birds, especially Weka Gallirallus australis
, may be a potential threat (F. A. Schmechel in litt.
1999). On Chatham, some pairs are forced to nest close to the tideline because introduced marram grass has spread and reduced the open areas it prefers: these nests are more vulnerable to high tides and storms, and flooding is the major cause of egg loss (B. D. Bell in litt.
1994, S. Sawyer per
G. A. Taylor in litt.
1994, Schmechel and Paterson 2005). Disturbance and trampling of nests by stock and vehicles may affect breeding success (Aikman et al.
2001). Hunting and collection for museums may have had a significant effect on the species's small population in the past (Moore 2008).Conservation Actions Underway
Mangere and South East islands were designated as nature reserves in the 1950s. Nest manipulation may have helped to increase hatching success on Chatham. Nests are moved slowly back up the beach to mitigate the impacts of flooding. Artificial incubation was trialled but did not increase overall productivity. Stock have been fenced from some beaches on Chatham, with strongly positive results (Moore 2009); signs have been erected to reduce human and dog disturbance, and marram is being controlled in some areas. Recently, intensive predator control combined with nest manipulation resulted in a high number of fledglings. A research programme aiming to assess the effects of predators, flooding and management on breeding success has been initiated (H. Aikman in litt.
1999, F. A. Schmechel in litt.
1999). Conservation Actions Proposed
Increase predator control at selected sites, and expand to other breeding areas (Department of Conservation 2001). Continue habitat management and dune restoration into a wider area (Waugh 2009). Continue nest manipulation. Continue research on population dynamics and monitoring of breeding activity. Minimise destruction of nests by domestic stock, dogs and people, through communication, education and possibly more fencing (Department of Conservation 2001).
Related state of the world's birds case studies
Aikman, H.; Davis, A.; Miskelly, C.; O'Connor, S.; Taylor, G. 2001. Chatham Islands threatened birds: recovery and management plans. Department of Conservation, Wellington, New Zealand.
Department of Conservation. 2001. Chatham Island Oystercatcher recovery plan 2001-2011. Department of Conservation, Wellington, NZ.
Heather, B. D.; Robertson, H. A. 1997. The field guide to the birds of New Zealand. Oxford University Press, Oxford, UK.
Moore, P. 2005. Chatham Island Oystercatcher population responds to conservation management. In: Anon. (ed.), Australasian Shorebird Conference, Nelson, New Zealand, 11-13 December 2005: Programme and Abstracts, pp. 10. OSNA, AWSG, NZWSG & DOC, Nelson, New Zealand.
Moore, P. 2007. Chatham Island Oystercatcher population responds to conservation management. Wader Study Group Bulletin: 8-9.
Moore, P. J. 2008. The recovering population of the Chatham Island Oystercatcher (Haematopus chathamensis). Notornis 55(1): 20-31.
Moore, P. J. 2009. Chatham Island oystercatcher Haematopus chathamensis management techniques. Guidelines for protecting nests and increasing their productivity. New Zealand Department of Conservation, Wellington, NZ.
Schmechel, F. A.; O'Connor, S. 1999. Distribution and abundance of the Chatham Island Oystercatcher Haematopus chathamensis. Notornis 46: 155-165.
Schmechel, F. A.; Paterson, A.M. 2005. Habitat selection and breeding ecology of the endangered Chatham Island oystercatcher (Haematopus chathamensis). New Zealand Department of Conservation, Wellington.
Waugh, S. 2009. Trip report: visit to Chatham Is for scoping for BirdLife Species Guardians work.
Further web sources of information
Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.
Click here for more information about the Alliance for Zero Extinction (AZE)
Explore HBW Alive for further information on this species
New Zealand Govt - Dept of Conservation - Recovery Plan
View photos and videos and hear sounds of this species from the Internet Bird Collection
Text account compilers
Benstead, P., Khwaja, N., Mahood, S., McClellan, R., Pilgrim, J., Taylor, J.
Aikman, H., Bell, B., Sawyer, S., Schmechel, F., Taylor, G.
IUCN Red List evaluators
Butchart, S., Symes, A.
BirdLife International (2016) Species factsheet: Haematopus chathamensis. Downloaded from
http://www.birdlife.org on 25/10/2016.
Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 25/10/2016.
This information is based upon, and updates, the information published in BirdLife International (2000)
Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004)
Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.
To provide new information to update this factsheet or to correct any errors, please email BirdLife
To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.
Additional resources for this species