Pseudonestor xanthophrys 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Fringillidae

Scientific Name: Pseudonestor xanthophrys
Species Authority: Rothschild, 1893
Common Name(s):
English Maui Parrotbill
Identification information: 14 cm. Chunky, short-tailed, big-headed passerine with huge parrot-like bill. Male olive-green above, yellow below with dark streak through eye and bold, sharply defined yellow superciliary. Two-toned bill, upper third of maxilla dark, remainder pale yellowish-pink. Female duller with much smaller bill. Similar spp. Nukupuu Hemignathus lucidus has yellow head without dark eye-line and bold superciliary, and much thinner bill. Voice Song a plaintive series of short whistles descending in pitch chwee-chwee-chwee-chwee-chwee. Calls include short warble, upslurred whistle, and loud chewp uttered by dependent juveniles, all similar to calls of Akiapolaau Hemignathus munroi of Big Island. Hints Only accessible site for observers is Waikamoi Preserve, where rare but regular. Best located by voice.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2015
Date Assessed: 2015-10-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A.
Contributor(s): Baker, H.C., Baker, P.E., Camp, R., Fretz, S., Gorresen, M., Lepson, J., Mounce, H., Pratt, T., Simon, J., VanderWerf, E., Woodworth, B. & Leonard, D.
Facilitator/Compiler(s): Benstead, P., Bird, J., Calvert, R., Derhé, M., Harding, M., Isherwood, I., Stattersfield, A., Stuart, T., Symes, A. & Wright, L
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.

Previously published Red List assessments:
2013 Critically Endangered (CR)
2012 Critically Endangered (CR)
2010 Critically Endangered (CR)
2009 Critically Endangered (CR)
2008 Critically Endangered (CR)
2004 Critically Endangered (CR)
2000 Vulnerable (VU)
1996 Vulnerable (VU)
1994 Vulnerable (VU)
1988 Threatened (T)

Geographic Range [top]

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).

Countries occurrence:
United States (Hawaiian Is.)
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 49
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 1
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Lower elevation limit (metres): 1200
Upper elevation limit (metres): 2150
Range Map: Click here to open the map viewer and explore range.

Population [top]

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).

Trend Justification:  The population is suspected to be declining owing to the effects of invasive species and other threats, although the rate of this decline has not been estimated. A study of reproductive success in 2006-2011 indicated that the population appeared to be demographically stable, however the study covered just 3% of the total range of the species (within the core of the range) and therefore may not accurately reflect the overall trend (Mounce et al. 2013).

Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 250-540 Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 1 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: Yes
No. of individuals in largest subpopulation: 100

Habitat and Ecology [top]

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). Studies in the Hanawi Natural Area Reserve (NAR) in east Maui in 2006-2011 found nest success probability of 19 % (n=30) and seasonal nest success of 46 %, with 49 of 106 breeding pairs monitored successfully producing one fledgling (Mounce et al. 2013).

Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 4.5
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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). Although they have not been documented as predators of parrotbill nests, rats have been documented predating Akohekohe nests at similar heights. Mounce et al. (2013) found no significant difference in reproductive success between birds in an area with predator control (bait stations loaded with rodenticide and snap traps) and those in an area without, suggesting that current control efforts may not be sufficient. 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 [top]

Conservation Actions: Conservation and Research 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). Control of invasive small mammals using bait stations takes place within the Hanawi Natural Area Reserve (Mounce et al. 2013). 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 (H. Mounce in litt. 2008) and 1,100 ha of mesic koa forest is currently being restored on leeward east Maui (Mounce et al. 2014). 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). Experimental releases are planned in the next five years (Mounce et al. 2014).

Conservation and Research 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). Due to their lower survival rates it has been suggested conservation measures focus on females and juveniles (Mount et al. 2014). 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, Mount et al. 2014). Improve techniques for successful captive breeding and release. Begin public outreach concerning the importance and benefits of controlling rodents (D. Leonard in litt. 2012), and initiate rodent control at a landscape scale. Supplementary feeding may also aid species recovery (Mounce et al. 2014).

Citation: BirdLife International. 2015. Pseudonestor xanthophrys. The IUCN Red List of Threatened Species 2015: e.T22720753A77800150. . Downloaded on 29 November 2015.
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