Archived 2016 topics: Chatham Parakeet (Cyanoramphus forbesi): Downlist to Vulnerable?

Cyanoramphus forbesi (Chatham, or Forbes’ Parakeet) is restricted to Little Mangere and Mangere Islands in the Chatham Island group, New Zealand. By 1930, it was extinct on Mangere Island, but by 1973 it had recolonised and numbered 40 birds and a small number of hybrids with C. novaezelandiae chathamensis (of which there were 12 on the island) (Higgins 1999). In 1996, the population was estimated at 120 birds (Aikman et al. 2001).

The Department of Conservation has collected trend data for parakeets on Mangere Island since 1999. Although many hybrids occurred in the early years of survey (e.g. Chan et al. 2006), this appears to have now changed in favour of Chatham Parakeets, possibly due to the impact of positive assortative mating (Greene 2000). The most recent population estimate is around 600 individuals, and this population level appears to have remained stable since 2003 (Aikman and Miskelly 2004, T. Greene in litt. 2016). A small cull of non-forbesi phenotypes was carried out in 2012, and since then only a small proportion <10% of hybrids has been observed (T. Greene in litt. 2016).

Although the population now appears stable, the greatest present threat to this species is hybridisation with C. n. chathamensis which, despite culling, continues to establish itself on Mangere Island (J. Kearvell in litt. 1999). The previously high rate of hybridisation is believed to be the result of the then low population sizes of the two species (D. Houston and C. Miskelly in litt. 2008). Levels of hybridisation have remained below 10% of the total Mangere Island parakeet population for much of the past decade. Ongoing vigilance for unsustainable levels of hybridisation will be required in future years.

As the population of C. forbesi is stable or increasing, and is now considered to have exceeded 250 individuals for more than five years, the species no longer qualifies as Endangered under criterion D. It therefore proposed to downlist it to Vulnerable under criteria D1 (population less than 1,000 mature individuals) and D2 (AOO <20 km2 and number of locations <5, with a plausible future threat that could drive the species to Critically Endangered or Extinct in a very short time).

Additional information and comments on this proposal are welcomed.


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.

Aikman, H.; Miskelly, C. 2004. Birds of the Chatham Islands. Department of Conservation., Wellington.

Chan, C.H., Ballantyne, K.N., Aikman, H., Fastier, D., Daugherty, C.J. and Chambers, G.K. 2006. Genetic analysis of interspecific hybridisation in the world’s only Forbes’ parakeet (Cyanoramphus forbesi) natural population. Conservation Genetics 7(4): 493-506.

Higgins, P. J. 1999. Handbook of Australian, New Zealand and Antarctic birds: parrots to dollarbirds. Oxford University Press, Oxford, U.K.

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2 Responses to Archived 2016 topics: Chatham Parakeet (Cyanoramphus forbesi): Downlist to Vulnerable?

  1. Terry Greene says:

    Always concerned when the entire population of a species is restricted to a ‘single’ island location but classification as vulnerable with the D1 and D2 criteria seems reasonable. We are still talking about the transfer of the species to other locations within the Chatham group (pest-free areas of the main Chatham Island?) and are looking to improve the monitoring methodologies currently employed on Mangere Island.

  2. James Westrip (BirdLife) says:

    Based on available information, our preliminary proposal for the 2016 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.

    There is now a period for further comments until the final deadline of 28 October, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from those in the initial proposal.

    The final 2016 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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