Introduced black (Rattus rattus) and Polynesian (R. exulans) rats are damaging to native birds, insects, and plants in island ecosystems. We controlled rodent populations in a montane rainforest on the island of Hawaii todetermine feasibility, cost, and effectiveness of ground-based rodent control in a rugged, remote rainforest habitat. Treatment was conducted 1996-99, from January to April each year, using rodenticide bait stations and snap-traps. We monitored rodent numbers in 48-ha treatment and reference areas before, during, and after control. As indexed by presence of rat sign in tracking tunnels or census blocks, rodent control reduced rodent abundance 58-90% each year 1 month after treatment began. There was an influx of rats into the treatment area, as shown by higher than expected numbers of rats snap-trapped on the treatment perimeter. Rodent numbers recovered to approximate pretreatment levels by the beginning of the following treatment year. Cost of equipment and supplies for rodent control for the first year was about $7,000 for a 1-km 2 grid. After the first year, cost decreased to about $2,000 for 1 km 2 per year. Rodent control applied continuously for 4 months each year during the breeding season may be effective in protecting nesting forest birds, but will not provide protection to plants and invertebrates vulnerable to predation throughout the year, and it is not likely to protect avian food resources.

Feral cat Felis catus home range in a Hawaiian montane wet forest and their diet in three habitats - montane wet forest, subalpine dry forest, and lowland dry forest ? were determined to provide baseline ecological data and to assess potential impacts to native terrestrial fauna. Seven cats (three males and four females) were captured in 624 trap nights. Mean weight of adult cats was 2.85 0.27 (SE) kg for males and 1.87 0.03 kg for females. Mean diurnal home range using the adaptive kernel method was 5.74 2.73 km2 for three males and 2.23 0.44 km2 for two females. Daytime locations were always within the montane wet forest with the borders on one or more sides of the home ranges of all cats defined by open grassland pastures. Rodents comprised the majority of the cat diets in all three habitats, with the frequencies of occurrence between 0.88 and 0.91. Bird remains were a regular component of the diet of cats, with montane wet forest having the highest frequency of occurrence (0.68), followed by subalpine dry forest (0.53). and lowland dry forest (0.21).

We studied populations of introduced rats in three areas in Hawaiian rainforests as part of a larger study to determine the factors limiting endangered bird populations. Species composition among 1 264 rats live trapped was Black Rats Rattus rattus 60.8%, Polynesian Rats R. exulans 38.1 %, and Norway Rats R. norvegicus 1.0%. Capture rates did not differ among the three study areas or four seasonal periods for any of the species. Males comprised 53.0% of 921 Black Rats and 55.3% of 783 Polynesian Rats that were sexed. Juvenile rats comprised 26.2% of Black Rats and 31.7% of Polynesian Rats captured and weighed. Black and Polynesian Rats reproduced throughout the year, but the highest proportion of juveniles in the population was captured in September-November and the lowest proportion in April-June. Mean home range size was 3.6 ha for four Black Rats (three males and one female) and 3.0 ha for three Polynesian Rats (two males and one female). All daytime nests of Black Rats found were above ground, generally in cavities within tree canopies. Mean annual rat activity in tree canopies as measured with tracking tunnels was 43% (range 21?80%). Of 44 rats captured in trees, 43 were Black Rats and one was a Polynesian rat.

A single, relictual population of Palila Loxioides bailleui, a Hawaiian honeycreeper, survives on the slopes of Mauna Kea volcano on the island of Hawai'i, where it feeds principally on flowers and green seeds of the mamane tree Sophora chrysophylla. The Palila was listed as an endangered species by state and federal governments because of continuing damage to its habitat by browsing Feral and Mouflon Sheep Ovis aries and O. musimon and Goats Capra hircus and because of the bird's restricted range and low numbers. Ecology of the Palila was studied from 1987 to 1996. Annual population estimates fluctuated between 1 600 and 5 700 and averaged 3 400 birds. Estimates varied with availability of mamane seeds, which are less abundant in drought years. In drought years, most birds did not attempt to breed, and survival rates were lower because of a shortage of food. Availability of mamane seeds also showed large seasonal variability. While some nests were preyed upon by Owls Asio flammeus, Cats Felis catus and Rats Rattus rattus, losses were high at the end of the season from unexplained death of eggs and chicks. Genetic studies did not implicate inbreeding depression. Neither avian malaria nor avian pox appeared at this site, where the mosquito vector was absent. However, weather and food shortage worsened towards the end of the nesting season. Availability of food and habitat remain the principal factors limiting increase in the Palila population. Recovery efforts now focus on reducing numbers of feral ungulates, fire management, removing mammalian predators, and developing techniques for captive propagation and introduction to currently unoccupied sites within the bird's former range. Reforestation adjacent to the Mauna Kea Forest Reserve would allow the Palila population to expand and grow.

Color change was recorded in 10 colors for 237 Hughes celluloid bands attached to the tarsi of 84 birds for up to 5 yr and for 45 celluloid bands exposed to natural sunlight on Mauna I;ea, Hawaii. Colors of four solid-colored bands (mauve, light green, yellow and black) and two split-colored bands (orange/dark green and dark blue/white) attached to free-flying birds were still recognizable greater than or equal to 3 yr. Within 2-3 yr, light blue, orange and red solid-colored bands and a red/white split-colored band had faded and could be confused with other colors. For studies less than or equal to 2 yr, most Hughes celluloid bands retained enough color to be recognized under field conditions. For long-term studies, biologists should select only those colors that can be recognized for the duration of the study or use another type of color band that is more resistant to fading or discoloration.

Annual survival, age, and sex ratios of the endangered Palila (Loxioides bailleui) on Mauna Kea, Hawaii, were determined from multiple captures and resightings of 984 individuals during 1987-1993. The proportion of Second Year (SY) Palila in the population was relatively constant among years, whereas the proportion of Hatching Year (HY) birds ranged from 3.1 to 22.6% over three years. Sex ratios of nestling and SY Palila did not differ from unity, but the sex ratio of HY and ASY Palila was male-biased. Mean proportion of adult males was 63.7% +/- 1.8 SE, and males outnumbered females in all six years of the study. Mean annual survival of HY Palila (0.36 +/- 0.08) was lower than that of After Hatching Year (AHY) birds (0.63 +/- 0.05), but annual survival of AHY males (0.65 +/- 0.07) did not differ from that of AHY females (0.62 +/- 0.06). Survival was negatively correlated with annual changes in the availability of green mamane (Sophora chrysophylla) pods, the primary food of Palila. The skewed adult sex ratio may result from greater emigration or mortality of KY females, or from greater mortality of breeding females due to increased exposure to predation.

Methods for identifying the sex and age of the Akiapolaau (Hemi~nalhus munroi), an endangered honeycreeper found only on the island of Hawaii, were developed by examination and measurement of 73 museum specimens and 24 live birds captured in mist nests. Akiapolaau probably undergo a single annual molt, with most birds molting between February and July. The mottled juvenal plumage is replaced by a first basic plumage characterized by yellowish-gray or yellowish-green underparts and often by retained wing- bars. Male Akiapolaau may not attain adult plumage until their third molt. In adult females, only the throat and upper breast become yellow, whereas in adult males the superciliaries, cheeks, and entire underparts are yellow. Adult males have greater exposed culmen, gonys, wing chord, tail, and tarsus lengths than do females. Akiapolaau in first prebasic molt or older can be identified as to sex by culmen length, that of males being >23.4 mm. Received I9 Aug. 1993, accepted I Dec. 1993. The Akiapolaau (Hemignathus munroi) is an endangered Hawaiian honeycreeper (Fringillidae: Drepanidinae) best known for its dual-action beak in which the mandible is a stout awl and the maxilla an elongated hook (Frontispiece). The species is distributed patchily through montane mesic and dry forest on the island of Hawaii, where Scott et al. (1986) estimated 1500 birds in low population density. This study describes the plumage sequence and morphometric and plumage characters for identi- fying the sex and age of Akiapolaau, based on museum skins and on live birds captured in mist nets. Previous descriptions of plumage and mea- surements from museum specimens are brief and incomplete (Wilson and Evans 1890-l 899, Rothschild 1893-l 900, Henshaw 1902, Amadon 1950), and recently published illustrations only show adult males with accuracy.

Methods to determine the sex and age of Apapane (Himatione sanguinea) and Iiwi (Vestiaria coccinea) were developed on the basis of 189 museum specimens and 91 live birds captured in mist nets on the Island of Hawaii. Both species retain all juvenal primaries and some juvenal secondaries and body feathers after the first prebasic molt and attain full adult plumage after the second prebasic molt. Apapane in their first basic plumage retain some buff-edged juvenal secondaries (particularly secondaries five and six) and sometimes retain a few gray-brown feathers on the head. The first basic plumage of Awe is characterized by secondaries 6-9 being longer and darker than secondaries 1-4 and the presence of a few yellowish juvenal body feathers with black spots at the tips. Adult male Apapane and Awe have longer wing, tail, exposed culmen, culmen and tarso-metatarsus lengths than females. Linear discriminant functions are presented to sex adult Apapane and Awe from lengths of their wing chord and exposed culmen.

-Methods to sex and age Palila (Loxioides bailleui), an endangered Hawaiian finch restricted to subalpine woodlands on Hawai'i, were identified on the basis of measurements and plumage characteristics of 17 museum specimens and 96 known-age, live Palila. Palila undergo a single annual molt during September-December following the breeding season. Presence of a complete or partial wingbar distinguishes hatch-year and second-year Palila from after-second-year birds. Adult male Palila are distinguished from females by a distinct napeline and <30% gray feathers intermixed with yellow feathers on the head. The black or gray feathers of the lores and chin of males are darker than those on the back, whereas the lores and chin of females are lighter or of the same shade as back feathers. IDENTIFICACION DE LA EDAD Y EL SEXO EN LOXIOIDES BAILLEUI Sinopsis.-Se desarroll6 un mhtodo para identificar la edad y el sexo de individuos de Palila (Loxioides bailleui), el cual es una especie en peligro de extinci6n. Esto se hizo utilizando medidas y caracteristicas del plumaje de 17 especimenes de museo y 96 individuos de Palila. El ave muda una vez al anio entre septiembre-diciembre, luego que pasa la epoca de reproducci6n. La presencia parcial o total de una barra en el ala diferencia a los individuos de primer y segundo anio de otros de mayor edad. Los machos adultos de Palila se diferencian de las hembras por una linea peculiar en la nuca y por tener un 30% menor de plumas con color entremezclado de gris y amarillo en la cabeza. El color negro o gris de las plumas de los lores y la barbilla en los machos es mas oscuro, que la misma coloraci6n en la espalda, mientras que los lores y la barbilla de las hembras son mas claros o de la misma tonalidad que las plumas de la espalda. The Palila (Loxioides bailleui) is an endangered Hawaiian finch (Fringillidae: Subfamily Drepanidinae) restricted to native forests above 2000 m on Mauna Kea, Island of Hawai'i. It was formerly more widespread on Hawai'i (Perkins 1903) and in the archipelago (Olson and James 1982, Scott et al. 1986); estimated population size was 1371 Palila in 1992, and has not exceeded 6500 birds during the past 13 yr (U.S. Fish and Wildlife Service, unpubl. data). Immature seeds of the mamane tree (Sophora chrysophylla) are the staple food of Palila, which also use mamane extensively for nesting and shelter. Browsing by feral ungulates was thought to have been a major cause of Palila decline (Scott et al. 1984). The U.S. Fish and Wildlife Service (FWS) conducted surveys of the Palila population in the mid-1970s (Scott et al. 1984), and, in 1987, began intensive studies of factors limiting Palila population growth. An impor' Current address: Hakalau Forest National Wildlife Refuge, 154 Waianuenue St., Room 219, Hilo, Hawai'i 96720 USA.