the South Pacific has increased considerably. Trees introduced by European colonizers have been naturalized and managed for lumber, agriculture, and ornamental purposes. Some of these trees include the Caribbean pine (Pinus caribaea), Moluccan albizia (Falcataria moluccana), and the African tulip tree (Spathodea campanulata). The introduced trees have altered the native forests historically dominated by the native hibiscus trees (Hibiscus tiliaceus). The sea-drifting hibiscus seeds are responsible for its high dispersal potential and establishment on islands throughout the tropical South Pacific (Takayama et al. 2006). There is a lack of research on the effects of a heterogeneous forest community structure on avifauna, especially on South Pacific Islands. A combination of avifauna field surveys and geospatial tools can provide insight into the distribution of birds in heterogeneous forests. The rapid development of remote sensing technologies for ecological research is an opportunity for science-based conservation and management. Remote sensing techniques contribute to conservation efforts through species distribution and abundance models, identifying areas for protection, revealing expansion of anthropogenic influence, and other applications (Rose et al. 2015). A combination of expensive technologies and time-intensive methods are required to produce remotely sensed data. The availability of open-source data, software, and analysis methods are necessary for applying remote sensing techniques to conservation and landscape ecology (Crowley and Cardille 2020). The classification of individual tree species in a forest from satellite imagery can be used to identify and evaluate forest habitat for avifauna, especially relevant in a heterogenous forest shaped by anthropogenic activity (Singh et al. 2017). Remote sensing of forest community structure can also be used to identify potentially suitable avifauna habitat in inaccessible locations where field surveys are difficult to accomplish (Shealer and Alexander 2013). High islands in the South Pacific are characteristic for their steep terrain and densely forested landscape, therefore comprehensive field surveys are very difficult and geospatial tools can be used to identify otherwise unknown suitable habitat for endemic avifauna. Identifying suitable habitat for endemic avifauna is particularly important for mitigating the impacts of competition with introduced bird species. The first objective of this study was to evaluate the relative differences in the distribution of endemic and introduced avifauna between different canopy-forming tree species in a heterogeneous tropical Pacific Island forest using field surveys and habitat characteristics. Endemic birds were expected to be more abundant in native and Polynesian-introduced canopy sites due to their ecological, evolutionary, and historical association. Introduced birds were 61 Fall 2021 / Perennial
expected to be more abundant in recent European-introduced canopy sites due to perturbation from native forest and facilitation of biological invasions. The second objective of this study was to provide insight on the forest community dynamics by evaluating the difference in avifauna community structure between different canopy sites in the forest using non-metric multidimensional scaling analysis (NMDS). Lastly, the third objective of this study was to infer habitat suitability from the revealed canopy site preferences and avifauna community dynamics to produce a site suitability model for endemic avifauna on the island of Moorea. METHODS Study site Moorea is a high island in the Society Islands archipelago of French Polynesia located in the South Pacific. This study took place in the island’s interior forest of the Opunohu Valley with a history of anthropogenic modification (Fig. 1). The protected forest of the upper valley is surrounded by steep cliffs and a mixed-use landscape including residences, agriculture, and recreation on the historic floodplain of the lower valley. The Opunohu Valley forest has a heterogeneous forest community structure includes trees from native, Polynesian-introduced, and European-introduced origins. This study focused on the distribution of birds between the canopy of three dominant trees including the native hibiscus (Hibiscus tiliaceus), Polynesian-introduced Mape (Inocarpus fagifer), and the European-introduced Moluccan albizia (Falcataria moluccana). While there are other tree species on the island, these three species were chosen because they are the most abundant tree on Moorea for their respective origin category. The native hibiscus tree is found throughout the South Pacific islands and arrived by sea-drifting seeds with a high dispersal potential (Takayama et al. 2006). Mape was introduced by Polynesians for arboriculture, food resources, and raw materials (Lepofsky and Kahn 2011). Moluccan albizia is considered a highly invasive plant that alters forest structure, soil biogeochemistry, and community ecology (Allison et al. 2006) introduced by the Agriculture Service in 1966 to reforest eroded and burned land (Bonnetaud 2003). These three large tree species provide most of the canopy habitat and a variety of resources for avifauna in the Opunohu Valley. Avifauna The two extant endemic birds (Appendix A) in the island’s forest are the Moorea kingfisher (Todiramphus youngi) and grey-green fruit dove (Ptilinopus purpuratus). The Moorea kingfisher is listed as “Near Threatened” by the International Union for the Conservation of Nature (IUCN; BirdLife International 2016a) due to habitat loss and degradation, impact of invasive species, and lack of knowledge on population size and dynamics (BirdLife International 2017). The grey-green