Justification of Red List Category
This species is listed as Critically Endangered because of its extremely small range and the imminent threat of feral deer impacting habitat. It remains at risk from the effects of exotic taxa. A particular concern is the possible introduction of a disease-carrying mosquito species tolerant of the cooler climate at higher altitudes, thereby bringing currently safe populations of birds into contact with lethal diseases.
Scott et al. (1986) estimated the population to number 3,800 individuals in total, roughly equivalent to 2,500 mature individuals.
Declines are suspected owing to a number of threatening processes that are likely to reduce the population size, although the likely overall rate of decline has not been estimated.
Palmeria dolei occurs on Maui in the Hawaiian Islands (USA) and is extinct on Moloka`i (last confirmed observations in 1907). On Maui, it remains moderately common within 58 km2 on the north-eastern slopes of Haleakala, with a population estimated at c. 3,800 birds in 1980 (Scott et al. 1986). Surveys in the 1990s to 1997 indicate stability, although areas outside protected areas were not necessarily covered (Jacobi and Atkinson 1995, Berlin and VanGelder 1999).
It occurs in mesic `ohi`a-koa and wet `ohi`a forest from 1,100-2,300 m (99% above 1,500 m, mostly below 2,100 m). It primarily feeds on `ohi`a nectar, also taking invertebrates, especially caterpillars. When `ohi`a bloom is at its seasonal low, it feeds on subcanopy and understorey flowers and fruit (Scott et al. 1986, Berger 1972, P. Baker in litt. 1999, J. C. Simon in litt. 1999). Average adult male home range is 0.56 ha, giving rise to density figures of 2.9 birds/ha (Pratt et al. 2001). All known nests have been in `ohi`a trees (Berlin and VanGelder 1999). It raises 1-2 young per nest, usually nesting twice seasonally (November to June [Simon et al. 2001]), and has a relatively high success rate (J. C. Simon in litt. 1999, Simon et al. 2001). Adult survivorship is similarly high (Simon et al. 2001). Birds, perhaps especially immatures, may disperse to lower elevations (Berlin and VanGelder 1999).
Habitat destruction and modification and the rapid spread of disease-carrying mosquitoes in the lowlands are thought to be responsible for past declines. The species may be particularly vulnerable to mosquito-borne diseases because it migrates altitudinally in response to varying `ohi`a flowering physiology, potentially increasing exposure to mosquitoes at lower elevations (USFWS 2003). From 1945 to 1995, the spread of feral pigs on Haleakala caused chronic habitat degradation (Loope and Medeiros 1995) and facilitated the spread of mosquitoes into remote rainforests (Pratt 1994). In Hanawi Natural Area Reserve, there was a 473% increase in pig activity, as indexed by ground-cover disturbance, during 1970-1997 (Rosa et al. 1998), and this reduced alternative food sources to `ohi`a bloom (Berlin and VanGelder 1999). Predation by introduced rats, cats, Barn Owl (Tyto alba) and possibly small Indian Mongooses (Herpestes auropunctatus) is a further limiting factor (Berlin and VanGelder 1999, J. M. Scott in litt. 1999, J. C. Simon in litt. 1999, E. VanGelder in litt. 1999). Climate change is an additional threat that may cause habitat shifts and extreme weather events.
Conservation and Research Actions Underway
Cooperative management of the East Maui watershed includes 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 combat the establishment of alien plants and, from the late 1980s, feral pigs have been controlled (Loope and Medeiros 1995, Simon et al. 1997). Research into captive breeding was attempted, and six individuals were hatched from late-stage wild eggs (USFWS 2003). A banding study investigating productivity and survival began in 2008 (Maui Forest Bird Recovery Project). A research project began in 2013 using radio-tracking to determine juvenile and adult habitat selection, dispersal and seasonal movements (Maui Forest Bird Recovery Project 2013).
18 cm. Large honeycreeper with slightly downcurved, sharp bill and distinctive forward-curving crest of stiff, white feathers on forehead. Mostly black, streaked and spotted with orange-red and silvery-grey. Shaggy red-orange patch on hindneck, orange-buff eye-ring and short postocular stripe. Orange-buff thighs. Primaries and tail feathers tipped white. Sexes similar, but juvenile all sooty-grey with orange-buff eye-ring and very short, grey crest. Voice Song a variable series of low-pitched notes ah-gurk-gurk-gurk or ah-koh-heh-koh-heh and many other variations. Call a human-like upslurred whistle.
Text account compilers
Benstead, P., Bird, J., Derhé, M., Harding, M., Isherwood, I., Stattersfield, A., Stuart, T., Symes, A., Wright, L & North, A.
Baker, P.E., Camp, R., Fretz, S., Gorresen, M., Simon, J., VanGelder, E., VanderWerf, E., Woodworth, B. & Mounce, H.
BirdLife International (2019) Species factsheet: Palmeria dolei. Downloaded from http://www.birdlife.org on 13/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/11/2019.