The mountainous, equatorial nation of Papua New Guinea (eastern half of the island of New Guinea; western half is Papua Province of Indonesia) supports a relatively low human population and retains large tracts of pristine or lightly modified natural habitats, from lowland swamp and rain forests to subalpine scrub and grasslands. All habitat types support diverse but incompletely documented mammal faunas, and many also host resource development projects in the mining, oil and gas, hydropower, forestry and agricultural sectors. While PNG environmental regulations and international lender regulations (e.g. IFC Performance Standards) demand a high standard of baseline documentation, impact mitigation, and monitoring, the primary taxonomic, distributional and ecological data needed to underpin rigorous assessments are often lacking. Field survey in remote and previously undocumented regions is challenging, and results obtained for mammals are often far less complete than for other survey target groups such as birds and amphibians. Analysis of owl pellet assemblages has multiple potential benefits in this context, including: 1) more complete species inventories than can be obtained by traditional methods; 2) detection of previously unknown mammal species; 3) detection of cryptic species through study of large series of specimens from single locations; 4) perspectives on relative abundance of species that are rarely encountered by conventional survey methods; and 5) evidence for locally reproducing populations through recovery of juvenile remains. Examples of each will be provided, and a case made for systematic use of owl pellet assemblages in biodiversity assessment and monitoring activities across wider Melanesia.