It inhabits lowland forest, including swamp-forest, up to 700 m locally (Coates 1985. Beehler et al. 1986, K. Sam in litt. 2016). Its ecology is poorly known but presumed to be similar to that of C. casuarius and is reported to be feed mainly on fruit, but also invertebrates and small vertebrates (K. Sam in litt. 2016). It is likely to have a critical ecological role as a seed disperser in New Guinea.

Casuarius unappendiculatus is restricted to the northern lowlands of New Guinea (Papua, formerly Irian Jaya, Indonesia, and Papua New Guinea). Its distribution on the Vogelkop is poorly known, but it is known from Yapen, Batanta and Salawati islands, and it extends east across the Ramu lowlands (Beehler and Pratt 2016). There are few records as this region is seldom visited.

Conservation Actions Underway
A survey of populations in fragmented landscape in Papua New Guinea has been conducted in Madang lowlands in logged and unlogged areas and in Wanang Conservation Area (Sam et al. 2014).

Conservation Actions Proposed
Survey distribution of this species and C. casuarius in Vogelkop using camera-trapping methods. Gather demographic data on the species to inform sustainable harvest calculations. Research and quantify the effects of hunting, and use this information to inform community-based wildlife management providing local communities with sustainable catch quotas. Research and quantify the effects of logging. Survey extensive areas through discussion with local hunters. Develop a repeatable monitoring technique in protected areas. Monitor populations in protected areas. Campaign for non-hunting protected areas in Papua New Guinea such as April-Saulemei or Ramu lowlands. Use this species as a figurehead for establishing ecotourism-funded protected areas. Liaise with Australian research and action on C. casuarius.