Justification of Red List Category
This species is classified as Vulnerable because it has a very small range and population and is therefore susceptible to stochastic events and the impacts of human activities, such as the introduction of non-native predators. Intensive conservation efforts aim to improve its status, but these have resulted in only partial success with at least three of the four remaining translocated populations requiring intensive and on-going management and the fourth currently at an early stage of establishment with uncertainty about its long-term survival.
The population is estimated to number a minimum of 3,000 mature individuals, assumed to equate to a total population of over 4,500 individuals, based on an estimated minimum of 3,000 mature individuals from distance sampling on Little Barrier (Department of Conservation unpublished report 2012, per J. Ewen, K. Richardson and P. Brekke in litt. 2012). Population estimates from each translocated population in 2011/2012 sum to c.430 adults (Department of Conservation unpublished reports 2012), but these are not counted in the total since it is uncertain how many translocated birds have bred successfully in the wild and can therefore be counted as mature individuals sensu IUCN.
No comprehensive surveys have estimated population trends on Little Barrier, where the only natural and self-sustaining population remains. However, it is not thought to be in decline there, although confirmation is needed.
Notiomystis cincta was once widespread over the North Island and adjacent offshore islands of New Zealand . Little Barrier Island (31 km2) is now the last natural population, with a minimum estimate of 3,000 birds. Translocated populations exist, with 150 adults on Kapiti (20 km2), 150 birds on Tiritiri Matangi (2 km2) Island, 65 birds at Karori Wildlife Sanctuary (2.25 km2) on the main North Island and about 71 birds at Maungatautari (34 km2), also on the main North Island (J. Ewen, K. Richardson and P. Brekke in litt. 2012). Population estimates are of adult birds at the start of the 2011/2012 Southern Hemisphere breeding season. None of the translocated populations are self-sustaining and most are only increasing as a result of intensive and on-going management including supplementary feeding and predator control at all sites, and the provision of nesting boxes and parasite control at most sites (Armstrong & Ewen 2001, Armstrong et al. 2002, Chauvenet et al. 2012).
It is found in most forest types, but requires mature forest for breeding as it nests in tree-cavities. It feeds on nectar, fruit and arthropods, depending on availability and requirements (Angehr 1984, Castro et al. 1994b). It has a highly variable breeding system, and is the only bird species known to mate facing each other (Castro et al. 1996). Forced copulation by males occurs during the breeding season (Low 2005). Rates of extra-pair paternity are very high (about 60% of offspring; Brekke et al. 2012). It lays between three and five eggs and can lay up to three clutches per breeding season, but can only rear a maximum of two.
Its extinction on the mainland may have been due to the introduction of black rats Rattus rattus or avian disease (Angehr 1984), although it probably also declined owing to forest loss in parts of its range (Department of Conservation 2005). Factors limiting the translocated populations have not yet been confirmed (D. P. Armstrong in litt. 1999), but declines in the translocated population on the island of Mokoia were attributed to aspergillosis and the discontinuation of supplementary feeding (Castro et al. 2003), and recent declines on Tiritiri Matangi have been attributed to an outbreak of salmonella (Ewen et al. 2007). Furthermore, the provision of supplementary food has promoted population growth on Kapiti (Chauvenet et al. 2012). The recovery of translocated small island populations may be hindered by inbreeding depression (Brekke et al. 2010). It appears to require large expanses of mature forest to survive which represents a major hurdle to conservation efforts (I. Castro in litt. 1999).
Conservation Actions Underway
Translocations were initiated in 1980 and have had mixed success with only four of eight sites establishing a population. Translocated birds are given supplementary food, and nest boxes are usually provided. Research to identify factors limiting the new populations indicates that translocation methods and availability of food were not key issues on Mokoia yet the population had poor viability and the last remaining birds were removed in 2002 (Armstrong et al. 1999, Armstrong and Perrott 2000), but food shortages and competition for food with endemic honeyeaters may be a problem on Kapiti (Castro et al. 1994a; Chauvenet et al. 2012) and Tiritiri Matangi (Armstrong and Ewen 2001). Initial signs of population establishment are promising for Karori (with on-going management) and Maungatautari (Ewen et al. 2011). Further sites are being assessed as potential locations for translocation. A small captive population is held, but numbers have gradually declined (Rasch et al. 1996) and the project will be discontinued as it is not cost efficient compared to sourcing wild bred birds for translocation. The population on Little Barrier Island is monitored and efforts are on-going to generate an accurate population assessment
Conservation Actions Proposed
Protect, monitor and, where necessary, enhance populations on existing transfer sites. Research the species's requirements to aid establishment of additional populations. Establish at least one more self-sustaining population. Survey the population on Little Barrier and establish viability and trends. Raise public awareness (Armstrong 1996).
18 cm. Small, sexually dimorphic passerine. Male, distinctive velvet-black head, back, upper breast. White erectile ear-tufts. Black underlined on breast with golden-yellow. Black wings with golden-yellow shoulder patches, white wing-bars. Remainder of underparts pale brown. Female, grey-brown with white wing-bar. Some females have small, non-distinctive white ear-tufts. Voice Male, loud explosive whistle see-si-ip, low warbling song of up to three minutes. Alarm calls stitch, whee whee whee.
Text account compilers
Khwaja, N., Benstead, P., Bird, J., Butchart, S., Symes, A., McClellan, R., Taylor, J., Wheatley, H.
Ewen, J., Castro, I., Brekke, P., Richardson, K., Boyd, S., Armstrong, D.P.
BirdLife International (2022) Species factsheet: Notiomystis cincta. Downloaded from http://www.birdlife.org on 28/09/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 28/09/2022.