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Black Robin Petroica traversi
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Justification
In 1980, this robin had the smallest population of any bird species for which precise figures were known and it seemed doomed to extinction. Its spectacular recovery, following intensive management, is a renowned conservation success worldwide. Although numbers continue to increase, it still has a very small population and is therefore classified as Endangered.

Taxonomic source(s)
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Identification
15 cm. Small, pure black bird. Plumage of sexes alike, but female slightly smaller. Short, slender, black bill. Voice Male song simple phrase of 5-7 notes. Call notes are distinct and full.

Distribution and population
Petroica traversi is endemic to the Chatham Islands, New Zealand. It declined rapidly during the late 1800s, and by 1980 the population had fallen to five birds, comprising three males and two females. Intensive management has resulted in a continuous increase in numbers: from seven adults pre-breeding in 1981 (12 post-breeding), to 93 in 1990 (128 birds post-breeding), 142 in 1995 (200 post-breeding) and 197 adults in 1998 (270 individuals post-breeding) (Kennedy 2009). The population is now restricted to Mangere (1 km2) and Rangatira (= South East, 2 km2) islands. The population was feared to be declining, based on census results in 2008, but it seems that the counts gave an underestimate due to weaker methodology and a decline in the species's detectability (E. S. Kennedy in litt. 2011). In 2011-2012, approximately 230 adults were counted in pre-breeding censuses of both island populations (D. Houston per E. S. Kennedy in litt. 2012).

Population justification
Full population surveys in spring 2011 found 190 mature individuals on Rangatira Island, and 34 on Mangere Island. A few birds were probably missed, and the total population size is therefore estimated at c.230 mature individuals in 2011 (E. S. Kennedy in litt. 2012).

Trend justification
Intensive conservation efforts boosted population sizes rapidly between 1980 and 1989 only. After intervention ceased, population sizes increased naturally though at a slower rate.. The most recent population estimate is higher than any since the population bottleneck of 1980 (E. S. Kennedy in litt. 2012).

Ecology
It lives in low-altitude forest remnants. It is entirely insectivorous, and feeds on the forest floor and low branches. It usually lays two eggs, and re-lays if a clutch is lost. Young normally begin to breed at one year of age (Kennedy 2009). Birds may pair for life. Survivorship under natural conditions between 1990 and 1998 indicates mean life-expectancy of 4.2 years for males, and 3.74 for females (both means are lower than for the intensively managed years, though not by much for males; Kennedy 2009). Some individuals may live up to 14 years, including Old Blue, the female breeding in 1980 from whom all Black Robins are now descended (Kennedy 2009).

Threats

The species appears to be intrinsically more extinction-prone than Petroica relatives, most of which have survived pressures which rapidly eliminated black robin populations (E. S. Kennedy in litt. 2012). The introduction of rats Rattus spp. and cats, following human settlement, extirpated the birds from all but Little Mangere Island (Butler and Merton 1992). The accidental introduction of mammalian predators to the islands where it currently survives could cause local extinctions. Introduced Common Starlings Sturnus vulgaris, which now number over 1,000 pairs on Rangatira, may provide a serious future threat through introduced disease, competition for nest sites and direct predation (Waugh 2009). Other potential predators include introduced mice Mus spp. and pigs Sus scrofa, as well as the native Weka Gallirallus australis (E. S. Kennedy in litt. 2012). A potential future threat to this highly inbred species is the arrival of new pathogens. Fire, catastrophic storm events and natural processes of forest recovery, exacerbated perhaps by climate change, are key extrinsic threats to habitat quality and extent. Chronic inbreeding and extensive loss of genetic diversity appear to compromise reproductive output and may yet threaten long-term viability in unforeseen ways. Hybridisation with congeneric Chatham Island Tomtits P. macrocephala chathamensis remains a concern, although the probability of recurrence may be low. The species remains susceptible to outright loss owing to stochastic events (E. S. Kennedy in litt. 2012).

Conservation Actions Underway
In 1976, following forest deterioration on Little Mangere Island, the seven surviving birds were relocated to Mangere Island. Prior to reintroduction, thousands of trees were planted to provide future habitat. In 1979, productivity failed to offset losses for the first time, and the population declined to five adults. In 1980-81, eggs and chicks were cross-fostered to the Chatham Island Warbler Gerygone albofrontata in order to induce Black Robin females to renest. Supplementary feeding commenced, along with protection of nests from seabirds and Common Starlings. The warblers proved unsuitable as foster-parents. In 1981-82, Old Blue’s eggs were cross-fostered to congeneric Tomtits P. macrocephala chathamensis on Rangatira Island. The chicks were returned to Mangere Island to assist future breeding there. Fostering to Tomtits proved successful, and in 1983 a permanent population of Black Robins was founded on Rangatira Island (E. S. Kennedy in litt. 2012). Intensive management ceased after 1989 (D. V. Merton in litt. 1994, Heather and Robertson 1997). Annual monitoring of numbers, reproductive success and distribution within habitats continues in both island populations (E. S. Kennedy in litt. 2012). Reforestation on both islands is on-going, and both island habitats are subject to strict quarantine measures to avoid introducing predators, pathogens and other threats. Further research into genetic threats is on-going, and reproductive success is being measured through the closer study of a large population sample on one island (E. S. Kennedy in litt. 2012).Conservation Actions Proposed
Continue to monitor population and demographic trends. Manage inbreeding threats by expanding populations sizes through reforestation of Mangere Island and infill planting on Rangatira Island . Protect populations on Mangere and Rangatira Islands (E. S. Kennedy in litt. 2012). Establish a third population within the Chatham Islands. Reintroduce birds to Little Mangere Island with landowners' support (H. Aikman in litt. 1999). Continue to work with landowners and Department of Conservation to provide safe habitat on Chatham Island.

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References
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.

Butler, D.; Merton, D. 1992. The Black Robin: saving the world's most endangered bird. Oxford University Press, Auckland.

del Hoyo, J.; Elliott, A.; Christie, D. 2007. Handbook of the Birds of the World, vol. 12: Picathartes to Tits and Chickadees. Lynx Edicions, Barcelona, Spain.

Department of Conservation. 2002. Black robin 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.

Kennedy, E. S. 2009. Extinction vulnerability in two small, chronically inbred populations of Chatham Island black robin Petroica traversi. PhD thesis. Lincoln University.

King, W. B. 1981. Endangered birds of the world: the ICBP bird Red Data Book. Smithsonian Institution Press and International Council for Bird Preservation [bound reissue of King 1978-1979], Washington, D.C.

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

Search for 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., Taylor, J., Temple, H., Symes, A.

Contributors
Aikman, H., Houston, D., Kennedy, E., Merton, D., O'Connor, S.

Recommended citation
BirdLife International (2014) Species factsheet: Petroica traversi. Downloaded from http://www.birdlife.org on 02/09/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 02/09/2014.

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

ARKive species - Chatham Island black robin (Petroica traversi) 0

Key facts
Current IUCN Red List category Endangered
Family Petroicidae (Australasian robins)
Species name author (Buller, 1872)
Population size 230 mature individuals
Population trend Increasing
Distribution size (breeding/resident) 4 km2
Country endemic? Yes
Links to further information
- Additional Information on this species