PALILA

The 'Palila' ('''Loxioides bailleui''') is an endangered finch-billed Hawaiian honeycreeper. It has a golden-yellow head and breast, with a light belly, gray back, and greenish wings and tail. The bird is in a close ecological relationship with the māmane tree. The palila is also an endangered species primarily due to destruction of māmane-naio woodland.

Contents

Physical Description

Systematics and nomenclature

Distribution and status

Ecology and behaviour

References

Footnotes

External links

Physical Description

Palilas have yellow heads and breasts, with white to light gray plumage ventrally, medium gray plumage dorsally, and olive-green wings and tail. The wings and the tails are greenish. The birds also have heavy dark bills with swollen sides, a brown iris, and dark feet with yellowish soles. The palila is one of the largest living Hawaiian honeycreepers, measuring around 6-7½ inches (15-18 cm).
There is some sexual dimorphism. Males tend to have brighter colors overall, as well as clear-cut black lores. The corresponding area contrasts less with the dirty-yellow heads in the marginally smaller females.
The bird's song is inconspicuous, containing whistling, warbling and trilling notes. The call is characteristic, however, being a clear, bell-like whistle, ''chee-clee-o'' or ''te-cleet''. This is loudly communicated between birds advertising food during the morning and evening, and according to native informants, it is given most frequently during the day as rain approaches (Rothschild 1900).

Systematics and nomenclature

The Hawaiian honeycreepers (Drepanididae) are sometimes included in the true finch family (Fringillidae). Oustalet scientifically described the palila in 1877. Named ''Loxioides bailleui'' by him, it was for some times united with several other "parrot-billed" Hawaiian honeycreeper species in ''Psittirostra''. Currently, the palila has again been moved to genus ''Loxioides'', which was long considered monotypic. The native name ''‘Ō‘ū-po‘o-papale'' ("capped ''‘ō‘ū''") probably refers to this species too (Rothschild 1900, FWIE 1996). Despite its bill and habits being somewhat similar to the ‘ō‘ū, its color pattern betrays a very close relationship with the genus ''Telespiza''.

Distribution and status

Currently, the palila can be found only on the upper slopes of Mauna Kea on the island of Hawai‘i. Palila live ranging from about 6,500 ft to 9,500 ft (2000 m to 2900 m) AMSL. The population density of the bird increases in areas where māmane grows more plentiful, and the birds do not appear to venture far from māmane stands. Essentially, this means that the species is confined - and may always have been so - to the area above the rainforest belt at around 3,000-4,500 ft (900-1400 m).
Palilas are today found in less than 10 percent of their historical range; they were found at elevations down to 4,000 ft. (1200 m) as late as the 19th century. Prehistorically, the palila may also have inhabited O‘ahu and Kaua‘i^[1].
A related larger species, Pila's Palila (''Loxioides kikuichi'') is known exclusively from subfossil remains found on Kaua‘i. It became extinct maybe as late as 1850, maybe much earlier. ''Loxioides bailleui'' was abundant throughout Hawai‘i until the beginning of the 20th century. It lived on the upper slopes of Mauna Kea, the northwest slopes of Mauna Loa, and the eastern slopes of Hualālai. Then, as early as 1944, scientists believed the bird almost extinct.
On March 11, 1967, palilas were listed as an endangered species under the ESA. In 1975, it was estimated that only 1,614 palilas existed. In 1978, federal courts ruled to remove feral sheep and goats from critical habitats of the bird. From annual counts between 1980 and 1996, variable estimates of population ranged from 1,584 to 5,685 mature birds, though there are no consistent trends. In 1997, the west slope of Mauna Kea contained 72% of the population. The entire population, an estimated 4,396 birds, occupied an estimated 78 km² (BLI 2004).

Ecology and behaviour

The palila favours dry māmane and māmane-naio forests. A habitat mix containing, apart from said forest, patches of grasslands, pukiawe shrubland on lava fields, and other types of native understory vegetation is optimal for their survival.
The diet of the palila is almost exclusively the immature seeds of māmane when these are available. These contain much vile-tasting phenolic compounds in the seed coat and a lethal amount of quinolizidine alkaloids in the embryos themselves. By some uas of yet undetermined means, adult palila are able to cope with a dose of these toxins that would kill other small animals in mere minutes. The amount of toxins in māmane varies, and the palila can be seen to avoid cetrain trees. It is possible that these contain the highest amounts of poison, but how the birds would be able to recognize this is not known.(Banko ''et al.'' 2002)
The bitter taste of the seed coats probably does not affect the birds (see below). Nonetheless, the seed coats are not very nutitious, and are thus discarded. Palila bills are adapted to open Fabales pods. The birds hold the pod with one foot and pry it open with the bill to expose the seeds. They then tear away the visible portion of the seed coat and extract the embryo, leaving the remaining coat in the pod. Seeds that drop out of the pod intact during opening are picked up and positioned longitudinally in the bill. The seed coat is then neatly cut open by the bill's edge and the embryo nudged out with the bird's tongue. The seed coat, still remaining in one piece, is then dropped.(Banko ''et al.'' 2002)
Palilas also eat naio berries and other fruit (such as the introduced Cape gooseberry: Rothschild 1900), and māmane flowers, buds, and young leaves. Additionally, they feed on caterpillars, particularly those of ''Cydia'' species (Māmane coddling moths) and more rarely on those of ''Uresiphita polygonalis virescens'' (Māmane snout moth). These caterpillars as well as other insects, along with the very nutritious māmane seeds, provide the palila's main source of protein. Nestlings, apparently not yet able to cope with the amount of poison contained in the seeds, are fed to a large extent on ''Cydia'' caterpillars. These destroy or discard the māmane's toxins they take up with their food, so that the caterpillars themselves are non-toxic. They do contained high amounts of phenolic compounds they probably sequester from their food and quite likely taste as bad. The palilas do not seem to mind the adverse taste or are physically unable to perceive it, given that they go at great lengths to obtain this food during breeding season. (Banko ''et al.'' 2002)
The abundance of mamane seeds affects reproduction rates and adult survival. Palilas start to eat the seeds at higher elevations and then gradually move downslope. During droughts, when mamane seeds are scarce, most birds do not even attempt to breed.
The birds breed from February up to September. The female constructs a loose, cup-shaped nest of some 4 in (10 cm) diameter high up in a māmane or naio tree. For this it uses grasses, stems, roots, lichen, and branch bark from the māmane trees provide the building material. Lichen and small leaves layer the inside of the nest. Usually the palila clutch size is two eggs. Both parents regurgitate food to feed their young. The juveniles remain in the nest for up to 31 days before fledging.

References

★ 'Banko', P.; Cipollini, M.L.; Breton, G.; Paulk, E.; Wink, M. & Izhaki, I. (2002): Seed chemistry of ''Sophora chrysophylla'' (Mamane) in relation to the diet of the specialist seed predator ''Loxioides bailleui'' (Palila) in Hawai'i. ''Journal of Chemical Ecology'' '28'(7): 1393-1410. PDF fulltext

★ Database entry includes justification for why this species is listed as endangered

★ 'Fish and Wildlife Information Exchange' (FWIE) (1996): [‘Ō‘ū, ESIS101027 (draft)]. Virginia Tech University. Version of 1996-MAR-14. HTML fulltext Disclaimer

★ 'Rothschild', Lionel Walter (1898-1900): 42. ''Loxioides bailleui''. ''In: The avifauna of Laysan and the neighboring islands'' (Vol.3): 197-198. R.H. Porter, London. JPEG/PDF fulltext

Footnotes

1.
The subfossil remains found on these islands are intriguing. They were found near sea level, where the habitat to which the species is restricted today apparently never occurred. Māmane might conceivably also have grown at lower elevations on the arid parts of Maui Nui. No palila remains have been discovered on these interspersing islands; it is thus quite possible that the birds from O‘ahu and Kaua‘i constitute a third species of ''Loxioides''.

External links

★ Jeffrey, John J., Fancy, Steven G., Lindsey, Gerald D., Banko, Paul C., Pratt, Thane K.,& Jacobi, James D. (1993). Sex and Age Identification of Palila, 64, Retrieved December 11, 2006 from http://elibrary.unm.edu/sora/JFO/v064n04/p0490-p0499.pdf.

★ U.S. Fish and Wildlife Service - Palila

★ National Audubon Society - Palila

★ Native Birds of Hawaii

★ Forest Birds

★ General Information

★ Palila - BirdLife Species Factsheet