Notes on the cultural value, biology and conservation status of the Data Deficient Tagula butcherbird (Cracticus louisiadensis Tristram, 1889)

Abstract

The Tagula butcherbird (Cracticus louisiadensis) is an endemic island species of butcherbird that has remained virtually unknown for over 130 years. The lack of information on the species has resulted in it being assigned to the Data Deficient category by BirdLife International and the IUCN, leaving its conservation status open to continuing speculation. This is an ongoing concern given the rapid environmental changes occurring in the region. Here, we describe the first observations of the habitat use, life history and ecology of the species. We also present information collected across the island distribution of the species, including density and population estimates. We found the Tagula butcherbird to be culturally important and relatively common in suitable habitats across four islands of the Louisiade Archipelago (Papua New Guinea). However, the species was absent from highly disturbed areas. We estimated this species’ extent of occurrence to be ~1200km2 and area of occupancy to be less than 800km2. Population densities were estimated via pre-dawn assessments of singing birds and line transects. Density estimates were found to be between 0.14 and 0.53 individuals per hectare, with the highest density observed on Sabara Island. These densities were combined with remote sensing data to estimate the amount of available habitat and the species’ population size, which was estimated to be between ~11500 and 23000 individuals. The species’ dependence on forest habitat with a relatively intact canopy, combined with the likely continuing destruction of habitat on Junet and Panawina Islands, remains a conservation concern.