|Scientific Name:||Pseudonestor xanthophrys|
|Species Authority:||Rothschild, 1893|
|Red List Category & Criteria:||Critically Endangered B1ab(iii) ver 3.1|
|Reviewer/s:||Butchart, S. & Symes, A.|
|Contributor/s:||Baker, H., Baker, P., Camp, R., Fretz, S., Gorresen, M., Leonard, D., Lepson, J., Mounce, H., Pratt, T., Simon, J., VanderWerf, E. & Woodworth, B.|
This species is listed as Critically Endangered because habitat within its extremely small range is being seriously degraded by introduced feral ungulates. Much of its range is now fenced so may be adequately protected from this threat, although the species remains at risk from chance environmental events, such as hurricanes, as well as habitat degradation and the effects of exotic taxa.
|Range Description:||This species is endemic to Maui in the Hawaiian Islands (U.S.A.), where it is found on the north-eastern slopes of Haleakala, although fossil evidence indicates that it once occurred in the lowlands and on Moloka'i. During 1976-1983, it was estimated to number c.500 individuals, of which 71% (c.355) occurred above 1,500 m (Scott et al. 1986). Density surveys in 1997 and 2001 suggested similar numbers in the 35 km2 of remaining suitable habitat above 1,525 m (Simon et al. 1997, D. Leonard in litt. 2012), and the number of birds detected on point counts since 1980 has not altered significantly, but further work is needed to confirm whether the population has genuinely remained stable (H. Mounce in litt. 2008).|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Extrapolating density estimates from 2001 over the species's estimated range gives a population estimate of 380-800 birds, roughly equivalent to 250-540 mature individuals (D. Leonard in litt. 2012).|
|Habitat and Ecology:||It is now restricted to montane mesic and wet forest at 1,200-2,350 m (mainly 1,500-2,100 m), and is absent from adjacent areas dominated by exotic trees (Mountainspring 1987, T. Pratt in litt. 1999, D. Leonard in litt. 2012). This habitat is probably marginal, as heavy rainfall leads to drastic losses during the breeding season (Simon et al. 2000). It feeds mainly on the larvae and pupae of wood- and fruit-boring beetles, moths and other invertebrates (Mountainspring 1987, Simon et al. 1997). Range size is c.2.26 ha and territories are defended year-round (Pratt et al. 2001). The nest is cup-shaped and placed in the outer canopy forks of mature ohia (Metrosideros polymorpha), a situation that may afford some protection from introduced predators (Simon et al. 2000). During the breeding season (between November and June), one chick is usually raised per year and young are dependent on parents for 5-8 months (Lockwood et al. 1994, T. Pratt in litt. 1999, J. C. Simon in litt. 1999, Simon et al. 2000).|
From 1945-1995, the invasion of feral pigs on Haleakala caused chronic habitat degradation (Loope and Medeiros 1995) and facilitated the spread of disease-carrying mosquitoes into remote rainforests (Pratt 1994). Most of the species's range is now fenced, and the species may respond positively as a result. However, the interaction between malaria and climate change is a potential future threat, as modelling has suggested a possible population decline of c.75% by 2090 (Hammond et al. 2009). Furthermore, having a montane distribution that is close to the maximum altitude within its range, this species is potentially susceptible to climate change (BirdLife International unpubl. data). Weather influences the survival of young and thus potential recruitment rates (Simon et al. 1997, Becker et al. 2010). Other limiting factors include predation and competition from exotic bird and insect species (Mountainspring 1987, Simon et al. 1997). Rats have been observed high in native 'olapa trees and are both a potential predator of eggs and young and a potential source of competition for berries (Maui Forest Bird Recovery Project 2008). Nest predation by Short-eared Owl (Asio flammeus) has been observed, though its extent and effect is unknown. Removal of small mammal nest predators may result in owl populations switching to a greater proportion of birds in their diet (Mounce 2008). Invasive plants represent a threat to habitat and require constant monitoring (D. Leonard in litt. 2012).
Conservation Actions Underway
Life history, genetic and demographic studies have been on-going since 2005 (D. Leonard in litt. 2012). The East Maui watershed is cooperatively managed with fencing at c.1,070 m and removal of feral ungulates (Loope and Medeiros 1995, P. Baker in litt. 1999). In the Waikamoi Preserve, Hanawi Natural Area Reserve and Haleakala National Park, conservation practices additionally combat the establishment of alien plants and, since the late 1980s, feral pigs have been controlled (Loope and Medeiros 1995, Simon et al. 1997). As a result, the forest understorey has recovered well and non-native plant invasions have slowed (Loope and Medeiros 1995, T. Pratt in litt. 1999). Rats are being poisoned (J. Lepson in litt. 1999), although only in a tiny area (H. Baker and P. Baker in litt. 2000). A small population exists in captivity, having bred for the first time in 2000 (Maxfield 2000), and numbered 10 individuals (3 males and 7 females) in 2003. Progeny from this flock will be used for a pilot release programme in the mesic forests of leeward East Maui where weather conditions may result in higher productivity (USFWS 2003). The Leeward Haleakala Watershed Restoration Partnership has been established to restore the south side of Maui's forests, and the state of Hawaii is working on fencing the leeward side which still contains some old growth koa - it is possible this may become a further suitable site for the establishment of a population (H. Mounce in litt. 2008). Conservation Actions Proposed
Carry out surveys to obtain an up-to-date estimate of the population size. Monitor population trends through regular surveys. Continue studies of life-history features (D. Leonard in litt. 2012). Complete and routinely check ungulate exclusion fences (Stone and Loope 1987, Lockwood et al. 1994, Loope and Medeiros 1995, Simon et al. 1997). Conduct research to assess the impact of ungulate exclusion. Complete ungulate eradication programme (Loope and Medeiros 1995, P. Baker in litt. 1999). Control alien plants, including outside the three wildlife protection areas (Loope and Medeiros 1995, Simon et al. 1997). Continue to replant koa forest in areas adjacent to its current distribution (Simon et al. 1997). Improve techniques for successful captive breeding and release. Begin public outreach concerning the importance and benefits of controlling rodents, and initiate rodent control at important sites (D. Leonard in litt. 2012).
|Citation:||BirdLife International 2012. Pseudonestor xanthophrys. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 19 May 2013.|
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