Long-Term Population Variability in the Palila, An Endangered Hawaiian Honeycreeper

Annual surveys of the entire range of the endangered Palila (Loxioides bailleui Oustalet) on Mauna Kea, Hawai'i, were conducted during 1980-1995. The majority of the Palila population was found on the southwestern slope of Mauna Kea near Pu'u La'au, and the range of Palila has not changed since 1975. The Palila population was highly variable. Mean population size during 1980-1995 was 3390 ± 333 SE, but the population ranged from 1584 ± 324 in 1985 to 5685 ± 535 in 1981. Population size outside the population center near Pu'u La'au has decreased significantly since 1980

A New Approach for Analyzing Bird Densities from Variable Circular-Plot Counts

An approach for calculating bird densities from variable circular-plot counts is described. The approach differs from previous methods in that data from several surveys are pooled and detection distances are adjusted as if all distances were recorded by a single observer under a given set offield conditions. Adjustments for covariates that affect detection distances such as observer, weather, time of day, and vegetation type are made using coefficients calculated by multiple linear regression. The effective area surveyed under standard conditions is calculated from the pooled data set and then used to determine the effective area surveyed at each sampling station under the actual conditions when the station was sampled. The method was validated in two field studies where the density of birds could be determined by independent methods. Computer software for entering and analyzing data by this method is described

Sex and Age Identification of Palila

Methods to sex and age Palila (Loxioides bailleui), an endangered Hawaiian finch restricted to subalpine woodlands on Hawai\u27i, 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 \u3c30% 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

Distribution and Population Status of the Endangered 'Akiapola'au

The 'Akiapola'au (Hemignathus munroi Rothschild) is an endangered Hawaiian honeycreeper that is found only in high-elevation native forests on the island of Hawai'i. The Hawai'i Forest Bird Surveys (HFBS) during 1976-1979 on Hawai'i found four disjunct populations of 'Akiapola'au totaling 1500 ± 400 (95% CI) birds. This total included 533 ± 320 in the Ka'u Forest Reserve and 46 ± 51 birds in dry mamane (Sophora chrysophylla [Salisb.] Seem.) forest on Mauna Kea. Because 'Akiapola'au are so rare, it was necessary to use data for other species to determine the effective area surveyed for 'Akiapola'au and to use data interpolation and smoothing techniques to derive the HFBS estimate of 1500 'Akiapola'au. We used a newly developed analysis approach to estimate the population size for 'Akiapola'au based on surveys conducted during 1990-1995. We plotted all recent detections of 'Akiapola'au and stratified the current distribution of the species based on distribution of koa (Acacia koa A. Gray) forests and elevation contours. A population estimate was derived by multiplying the density of 'Akiapola'au within each stratum, as determined from variable circular plot counts, by the area within each stratum. We estimate that there are 1163 ± 54 (90% CI) 'Akiapola'au in the world. The distribution of 'Akiapola'au has been greatly reduced in the Ka'u District, where the estimated population has declined from 533 to 44 birds, and relic populations in mamane forest and South Kona are likely to become extinct within the next 5 yr. Protection and management of the remaining isolated stands of koa forest at higher elevations where mosquitoes are absent or occur only seasonally are critical to the survival of this species

Site Tenacity of the Endangered Palila

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