Bird Diversity on Tanimbar Islands with Special Reference to the Tanimbar Corella (Cacatua goffiniana)

Abstract

The Tanimbar Islands located in the Wallacea region have particularly important ornithological values due to high level of endemism. Avian researchers have carried out expeditions to Tanimbar since long time ago starting with Forbes in 1882. An iconic bird of the Tanimbar Islands is the endemic Tanimbar corella (Cacatua goffiniana). This species is considered near threatened by the IUCN, listed in CITES Appendix I, and is protected under Indonesian law. The objectives of the study were to assess bird diversity, habitat use, and association between C. goffiniana and other bird species on the Tanimbar Islands. Data were collected between 2015 and 2019 on Yamdena, Larat, Selaru, and Vaimar Island of Kepulauan Tanimbar Regency, Maluku Province. Direct observation and mist-netting technique were conducted to assess the bird diversity. The habitat use was mapped using ArcGIS 10.5. Descriptive analysis was used to reveal associations between Tanimbar corella and other species. The diversity assessment recorded 142 species in which there were 13 new records for this location. The Tanimbar Islands offer several types of habitats, namely forests, open land, swamps, mangroves, and coastal areas. Associations between C. goffiniana and other birds were recorded with regards to competition and sharing of food resources and nesting sites. C. goffiniana competes with Eclectus roratus for nesting opportunities, and they have an overlapping diet. In addition, C. goffiniana often shares nesting sites with Eos reticulata or Aplonis crassa by using the same trees, and sometimes even the same hollows for nesting. During the observation in August-November 2015, several species were found entering breeding period, namely C. goffiniana, E. roratus, E. reticulata, A. crassa, Philemon mollucensis, Chalcophaps indica, Rhipidura rufifrons, and Lonchura quinticolor. Deforestation resulting in loss of nest and foraging trees pose the major threat to the wild bird population, especially C. goffiniana. By promoting C. goffiniana as an umbrella species we expect to conserve the biodiversity in the region.