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Haematopus chathamensis

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES CHARADRIIFORMES HAEMATOPODIDAE

Scientific Name: Haematopus chathamensis
Species Authority: Hartert, 1927
Common Name/s:
English Chatham Oystercatcher, Chatham Islands Oystercatcher, Chatham Island Pied Oystercatcher
Taxonomic Notes: Haematopus unicolor (Sibley and Monroe 1990, 1993) has been split into H. unicolor and H. chathamensis following Turbott (1990).

Assessment Information [top]

Red List Category & Criteria: Endangered D ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor/s: BirdLife International
Reviewer/s: Butchart, S. & Symes, A.
Contributor/s: Aikman, H., Bell, B., Sawyer, S., Schmechel, F. & Taylor, G.
Facilitator/s: Benstead, P., Khwaja, N., Mahood, S., McClellan, R., Pilgrim, J., Taylor, J.
Justification:
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.

Geographic Range [top]

Range Description: Haematopus chathamensis 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).

Countries:
Native:
New Zealand
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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.
Population Trend: Increasing

Habitat and Ecology [top]

Habitat and 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).

Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): 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 [top]

Conservation Actions: 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).

Citation: BirdLife International 2012. Haematopus chathamensis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 17 April 2014.
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