Justification This species is classified as Critically Endangered owing to an extremely rapid decline in population size over the last ten years. Urgent action is required to halt the decline of this species, which until relatively recently was considered not uncommon.

Family/Sub-family Fringillidae

Species name author (Wilson, 1890)

Taxonomic source(s) AOU checklist (1998 + supplements), Sibley and Monroe (1990, 1993)

Identification 11 cm. Small, finch-like bird with notched tail and conical bill with slightly crossed tips (hard to see in the field). Male basically olive-green above, yellow below, with black mask surrounding bill to behind eye. Yellow forehead, forecrown and rump. Pale blue bill sometimes with dark tip. Female similar except colours muted and black mask less extensive. Similar spp. All other "little green birds" on Kaua`i (Kaua`i `Amakihi Hemignathus kauaiensis, `Anianiau H. parvus, introduced Japanese White-eye Zosterops japonicus) have dark rumps. Kaua`i Nukupu`u H. lucidus hanapepe has yellowish rump, but is much larger with longer black bill. Voice Songs are lively trills that shift pitch and speed. Call a piercing, upslurred szeet. Hints Feeds almost exclusively in terminal leaf clusters of ohi`a trees (not in flowers). Can be seen on trails east of Koke`e.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

2,500 - 4,566

decreasing

160 km²

Yes

Range & population Loxops caeruleirostris is endemic to Kaua`i in the Hawaiian Islands (USA). It was common throughout upper elevation forests in the late 19th century and was thought to be stable at c.20,650 individuals up until the mid 1990s, although its habitat has declined in extent over this time period<sup>3,6,7,8</sup>. However, in 2000 surveys indicated that the population was 7,839 ±704 individuals, this has since decreased to 5,669 ± 1,003 individuals in 2005 and to 3,536 ± 1,030 in 2007. Even allowing for the large error estimates this indicates a dramatic decline<sup>9,10,11,13</sup>. It occurs at the highest density in the remote Alaka`i region, and also occurs in the upper Waimea and Koke`e regions, and an isolated population persisted in the Makaleha Mountains until at least the early 1970s^3,6.

Ecology: It inhabits wet `ohi`a, `ohi`a/olapa and diverse mesic forest, appearing to tolerate considerable habitat disturbance if sufficient `ohi`a remains. It is found at 600-1,600 m, mostly above 1,100 m, and apparently never occurred in lowland forests. It feeds primarily on spiders and insects, taking nectar very rarely. Breeding occurs at least in March and April, possibly February to June, and all known nests have been in `ohi`a trees³.

Threats Development is reducing habitat availability in the Koke`e region, while the spread of exotic plants and feral ungulates is degrading remaining areas<sup>3,4</sup>. Avian pox and malaria probably cause mortality because introduced mosquitoes (vectors for these diseases) are now common at 900 m, may breed at 1,200 m, and appear to be encroaching on the Alaka`i plateau^1,2,3. There is concern that rising average temperatures could allow mosquitoes to survive at higher elevations and increase the exposure of birds to disease⁹. A small increase in temperature is predicted to eliminate much of the mosquito-free zone on Kaua`i<sup>12</sup>. Food resources may be limited by alien wasps and ants which greatly reduce populations of native arthropods<sup>3</sup>. Introduced birds may be competitors and introduced predators, especially rats, probably cause some mortality<sup>3</sup>. Adverse weather may be a significant limiting factor, e.g. prolonged, heavy rains which can result in nesting failure and cause massive mortality among fledglings and juveniles<sup>3</sup>. Two recent hurricanes resulted in serious damage to Kaua`i's forests⁵.

Conservation measures underway Much of the current range is protected by Alaka`i Wilderness Preserve and, to some extent, by Koke`e State Park. In April 2007, the Hawaii Department of Land and Natural Resources began to conduct population surveys of forest birds on Kaua`i to verify anecdotal evidence of a recent crash in the species's numbers⁹.

Conservation measures proposed Continue to conduct population surveys, especially in peripheral parts of its range. Research basic ecology. Prevent further habitat degradation and restore habitat. Control and prevent further introductions of alien species; fence out and remove invasive species⁹. Identify and translocate disease-resistant birds to parts of the historical range that are affected by disease-carrying mosquitoes³. Initiate a captive breeding programme⁹. List under the Endangered Species Act as a matter of emergency⁹.

References 1. Herrmann and Snetsinger (1997). 2. Lepson (1997). 3. Lepson and Pratt (1997). 4. Loope and Medeiros (1995). 5. Pratt (1994). 6. Scott et al. (1986). 7. USFWS (1983). 8. S. Fretz et al. in litt. (2003). 9. Holmer (2007). 10. D. Kuhn per Holmer (2007). 11. D. Pratt per Holmer (2007). 12. U.S. Geological Survey per Holmer (2007). 13. VanderWerf (2007).

Further web sources of information

Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Audubon WatchList

Text account compilers Phil Benstead (BirdLife International), David Capper (BirdLife International), Isabel Isherwood (BirdLife International), Simon Mahood (BirdLife International), Alison Stattersfield (BirdLife International), Tom Stuart (BirdLife International), Andy Symes (BirdLife International), Joe Taylor (BirdLife International), P. Barry Taylor (University of Natal)

Contributors Rick Camp (US Geological Survey), Scott Fretz (Hawaii Division of Forestry and Wildlife), Marcos Gorresen (US Geological Survey), Pauline Roberts (Hawaii Division of Forestry and Wildlife), Eric VanderWerf (Pacific Rim Conservation), Bethany Woodworth (US Geological Survey)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Andy Symes (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Loxops caeruleirostris. Downloaded from http://www.birdlife.org on 9/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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