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Loxioides bailleui

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES PASSERIFORMES FRINGILLIDAE

Scientific Name: Loxioides bailleui
Species Authority: (Oustalet, 1877)
Common Name(s):
English Palila

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A4bce ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Baker, H., Baker, P., Banko, P., Becker, D., Brinck, K., Camp, R., Farmer, C., Fretz, S., Gorresen, M., Leonard, D., Pratt, T., Scott, J., VanderWerf, E., Wallace, G. & Woodworth, B.
Facilitator/Compiler(s): Benstead, P., Calvert, R., Capper, D., Derhé, M., Harding, M., Stattersfield, A., Stuart, T., Symes, A., Taylor, J., Khwaja, N.
Justification:

This species has is listed as Critically Endangered because it has suffered extremely rapid annual population declines since 2003. The primary short-term driver of the decline is prolonged drought, which has reduced mamane pod production, but other contributing factors include habitat degradation by introduced ungulates, predation by introduced cats, and competition for caterpillar food from introduced parasitoid wasps.

Geographic Range [top]

Range Description: This species is restricted to Big Island in the Hawaiian Islands (U.S.A.), where it was abundant, although locally distributed, until the beginning of the 20th century, and evidence from the fossil record suggests that the species occurred throughout the archipelago prior to human settlement (C. Farmer in litt. 2007). In 1997, it occupied an estimated 78 km2 and numbered 4,396 birds, mostly on the western slope of Mauna Kea, where 20.5 km2 was estimated to hold 72% of the total population (Scott et al. 1986, Fancy et al. 1997, Banko et al. 1998). Comparison of annual counts from 1980-2007 suggests that the population size has historically been subject to fluctuations (1,007-6,356 individuals), but since 2003 it has undergone a consistent and rapid decline (58% in the core population between 2003-2007 and projected to reach 96.6% over three generations or 14 years) (Leonard et al. 2008). In 2007, the population was estimated at 3,866 individuals (C. Farmer in litt. 2007), and has been declining since, with data from 2008 estimating a population of 2,640 individuals (Leonard et al. 2008) and data from 2009 indicating a population of 2,512 individuals (G. Wallace in litt. 2009). Survey results from 2010 suggest that the decline is worsening, with the estimated population size down to only c.1,200 individuals (American Bird Conservancy 2010). The species's range remains centred on the western slope, and it has contracted such that c.96% of the population is found in 3,000 ha of forest (G. Wallace in litt. 2009). It has not been found in annual surveys on the east slope since 2004 (P. Banko in litt. 2007, C. Farmer in litt. 2007). A small colony of reintroduced individuals has been extirpated on the northern slope (C. Farmer in litt. 2007, P. Banko in litt. 2012).

Countries:
Native:
United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Survey results from 2010 suggest that the population numbered c.1,200 individuals, thus the number of mature individuals is estimated to fall in the range of 250-999.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: It is confined to altitudes of c.2,000-3,000 m, favouring dry mamane and mamane-naio forest. It feeds primarily on mamane seeds, flowers, and insects (Banko et al. 1998), with the availability of mamane seeds affecting productivity and adult survival. In drought years, most birds do not attempt to breed (Jacobi et al. 1996, Pratt et al. 1997). The species exhibits low rates of reproduction (Banko 2006), laying fewer eggs and taking longer to raise its young compared with mainland songbirds (Hess and Banko 2006).

Systems: Terrestrial

Threats [top]

Major Threat(s): The most significant declines in this species's range and population are thought to have been caused by human-induced habitat loss and degradation and predation by introduced rats prior to Western settlement (C. Farmer in litt. 2007). The subalpine forest habitat of this species has been severely overbrowsed by feral and domestic ungulates, and nests and adults are preyed upon primarily by feral cats but also by introduced black rats Rattus rattus, Short-eared Owl Asio flammeus, and rarely Hawaiian Hawk Buteo solitarius (C. Farmer in litt. 2007, P. Banko in litt. 2012). Up to 11% of nests are depredated by feral cats each year (Hess and Banko 2006). Grazing by cattle was a historical factor in the species's decline, although cattle are now limited to pastures that are unsuitable for L. bailleui (C. Farmer in litt. 2007). Alien grass cover is high in much of the species's range (Banko 2006), suppressing mamane regeneration and potentially increasing the threat of fire. Increasing human activities, such as military training, could further increase the chances of fire (C. Farmer in litt. 2007). In 2006-2007, there were numerous fires on and near Mauna Kea, and fires in August and September 2010 affected c.560 ha of suitable habitat on the southern slope of the mountain (American Bird Conservancy 2010). A fire in the species's core area could potentially affect 50-90% of the population. The recent opening of trails for all-terrain vehicles in the Mauna Kea Forest Reserve is a concern (C. Farmer in litt. 2007), and may cause disturbance and habitat degradation. Continuing threats include grazing by feral sheep, wild sheep Ovis gmelini musimon, and their hybrids, which slows mamane regeneration (Pratt et al. 1997, Banko 2006, C. Farmer in litt. 2007), and alien insects preying on and parasitising native insects (Pratt et al. 1997, Banko 2006), particularly at low elevations (Banko 2006). Native caterpillars are an important source of protein for nestlings, and possibly breeding females; however, they are preyed upon by yellow-jacket wasps Vespula pensylvanica and several ant species, particularly Argentine ants Linepithema humile, whilst parasitoid wasps kill the caterpillars by laying their eggs on or inside them (Banko 2006). In addition to the aforementioned threats, this species's very restricted range means it could be extirpated by extreme events such as drought and storms (Banko 2006), and drought is thought to be contributing to the species's recent decline (C. Farmer in litt. 2007). Demographic patterns of mamane mortality are under investigation, as mamane may be under threat from pathogens (USFWS 2003). Climate change may pose a long-term future threat to the species, as drought frequency and intensity are expected to increase at higher elevations (Benning et al. 2002, Giambelluca and Luke 2007).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
The species's population has been monitored since 1980 (Banko 2006). In 1979, 1987 and 1998, federal courts ordered the eradication of feral goats and feral and wild sheep species from the species's habitat on Mauna Kea, and these rulings have remained in effect despite six legal challenges (Banko 2006, P. Banko in litt. 2007, Banko et al. 2009). Forest regeneration has improved as a result, although current efforts to reduce sheep have not been sufficient to allow the complete recovery of mamane forests (Banko 2006). Despite such efforts, the species's strong site-tenacity might prevent recolonisation of areas of recovered forest. In 1993, some birds were translocated to a new site where predators were controlled and, although many homed back to their capture site, at least two pairs stayed and bred successfully (Fancy et al. 1997). Six additional translocations have taken place since, and by the end of 2006, 188 wild birds had been translocated from the western to the northern slope of Mauna Kea (C. Farmer in litt. 2007). Approximately 34% persisted for longer than two months, and a small colony of up to c.23 birds remained on the northern slope and bred successfully until 2010. Although F2 generation offspring were observed, the colony was not sustainable without additional management (Banko et al. 2009) and it was extirpated by 2011 (P. Banko in litt. 2012). Egg-laying occurred in 2004, and independent juveniles were produced in every year from 2005-2007 (C. Farmer in litt. 2007). This translocation programme has been aided by a captive breeding programme initiated at the Keauhou Bird Conservation Center in 1996 (USFWS 2003, Banko 2006). Of 28 captive-reared birds released in 2003-2009, at least 10 persisted in the reintroduction area for at least one year, with 2 males breeding with translocated wild females in the north slope colony before its extipration (C. Farmer in litt. 2007, P. Banko in litt. 2012). The construction of a highway through unoccupied, federally designated critical habitat was approved in 1999. A mitigation plan accompanied the development, including the suspension of cattle grazing in pastures adjacent to the species's range. The species's conservation is the subject of detailed research, and funding from the mitigation plan supported translocation research and enabled the expansion or continuation of studies into the species's ecology and limiting factors, mamane ecology, food availability, predator ecology and management, and fire ecology. Habitat restoration and research into restoration methods are on-going (D. Leonard in litt. 2007). Work is being carried out to restore habitat by controlling fountain grass Pennisetum setaceum, which increases the frequency and intensity of fires, and Cape ivy Delairea odorata, which reduces the vigour of native trees (American Bird Conservancy 2010). Hawaii State and federal agencies have begun programmes to control cats and rats (Pratt et al. 1997, E. VanderWerf in litt. 1999). Reforestation is also taking place on the northern slope of Mauna Kea (American Bird Conservancy 2010). Goats have been virtually removed from the mountain (C. Farmer in litt. 2007), and the plan to build an 87-km-long fence enclosing all of Palila's critical habitat to prevent the ingress of sheep and goats has been completed (G. Wallace in litt. 2009, American Bird Conservancy 2010). The fence is c.2 m high and encloses c.94 % of the species's habitat. In 2010, a comprehensive fire management plan was being developed for the Mauna Kea area (American Bird Conservancy 2010).

Conservation Actions Proposed
Establish protocols and make preparations to control fire (Pratt et al. 1997). Intensify control of mammalian predators (especially feral cats) and grazing ungulates (Pratt et al. 1997, H. Baker and P. Baker in litt. 1999, T. Pratt in litt. 1999, P. Banko in litt. 2007). Continue to expand the application of translocations and captive propagation for introducing the species to currently unoccupied sites within the former range (Pratt et al. 1997, C. Farmer in litt. 2007). Reforest areas adjacent to the Mauna Kea Forest Reserve and areas where alien grasses and grazing threaten mamane (Pratt et al. 1997). Carry out forest restoration research to find ways to accelerate the rehabilitation and regeneration of mamane trees within the Mauna Kea Forest Reserve. Remove and fence out ungulates from all critical habitat and the mitigation parcels (Banko 2006, C. Farmer in litt. 2007). Continue to restore forest above Hakalau Wildlife Refuge (Benning et al. 2002).


Citation: BirdLife International 2012. Loxioides bailleui. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 26 November 2014.
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