The U.S. Geological Survey and University of Hawaiʻi at Hilo published a report, Palila Restoration Research, 1996–2012, which summarizes long-term studies on the conservation biology of the palila (Loxioides bailleui), a critically endangered Hawaiian forest bird found only on the upper slopes of Maunakea Volcano. The report has been published by the UH Hiloʻs Hawaiʻi Cooperative Studies Unit as part of its technical reports series
With the publication of this report, the palila becomes the most thoroughly documented Hawaiian bird species. Topics covered in this extensive report include population dynamics and restoration research, demography and breeding ecology, predator ecology and management, habitat use, food ecology, vegetation ecology and management implications.
The report details how research results can be applied to the conservation of the palila and restoration of its habitat. “Some results can be expected to have immediate, practical value; whereas, other information is more likely to enlarge our understanding of the species so that conservation strategies can be adjusted as conditions change,” said Paul Banko, U.S. Geological Survey biologist and co-editor of the new volume.
The major goal of the population and restoration research was to develop methods for reintroducing palila to former range and for enhancing the main palila population on the western slope of Mauna Kea. This work involved evaluating sites where palila could be reintroduced, translocating wild palila to northern Mauna Kea to start a new colony (supplemented by palila bred in captivity by the San Diego Zoo). Translocating palila proved successful in establishing a small breeding colony of palila on the northern slope of Mauna Kea that persisted for a number of years before disappearing during severe drought.
A key aspect of the research was documenting the roles of drought and habitat damage by feral sheep in the sharp decline in palila numbers after 2003. One of the outcomes of the decline was the disproportionate number of male palila in the population, suggesting that females suffered greater mortality under stressful conditions. Although palila were found to be at lower risk for mosquito-borne diseases than are most other Hawaiian birds, their reproductive capacity is low, based on studies of the demographic characteristics of the breeding population, productivity of breeding pairs and nesting success.