It normally breeds, often in dense colonies, on extremely small, wooded offshore islands and forages in situ or on adjacent mainland (or larger island) areas up to at least 500 m. It prefers uninhabited and remote islets with original forest vegetation, though these must be close enough to large areas of lowland rainforest which it requires for foraging. It may persist in secondary habitats and occasionally tolerate logged forests (Baptista et al. 2020). Nests in trees and shrubs and has a clutch size of one (Pratt and Beehler 2015). Its primary diet consists of fallen fruits and seeds, and occasionally invertebrates (Baptista et al. 2020).

Caloenas nicobarica is a small island specialist. It occurs on the Andaman and Nicobar Islands, India, Mergui archipelago (Myeik Kyunzu; occurring mostly in remote islands with big forests [N. M. Shwe in litt. 2020]), Myanmar, islands off south-west peninsular Thailand, islands around Peninsular Malaysia, islands off southern Cambodia and Vietnam, islands around Sumatra, Wallacea and Papua (formerly Irian Jaya), Indonesia, Timor-Leste, many islands in the Philippines, islands in Papua New Guinea and throughout the Solomon Islands, plus Palau (race pelewensis). Generally scarce throughout its range, it is most abundant on the smallest, least disturbed islands. The distinctive race pelewensis was thought to still number up to 1,000 birds in 1985; it is considered to only occur on the small "rock island", south of Koror (Baptista et al. 2020). Across Bornean offshore islands (Sipadan, Matasirih, Kadapangan, and Marabatuan), the species is likely rare (Baptista et al. 2020). Records are moreover sparse from the Indonesian islands of Halmahera, Bacan, coastal Obi, Sumbawa, Flores, Togian Island, Banggai Island, Sula Island, Sangihe, Karakeland, submontane forests on Seram, and several small islands off Irian Jaya. The species has not seen recent records from Negros and has been scarce on Siquijor, perhaps even extirpated from Western Visayas. The species is locally common on some offshore islands off Sumatra but is likely rarer throughout the Greater Sundas (Baptista et al. 2020).

Conservation Actions Underway
CITES Appendix I. A small population in Vietnam is protected within Con Dao National Park; however, records have been restricted to just two islands in recent years (Tre Nho, with nine birds recorded in 2012 and Bay Canh, with eight individuals recorded in 2007) (Le 2013).

Conservation Actions Proposed
Research population size and trends. Protect known breeding islands from clearance for plantations. Preserve areas of lowland forest close to breeding islands. Educate people who live close to breeding islands to prevent trapping for food and the pet trade. Eradicate rats, cats and other alien predators on particularly important breeding islands. Prevent further introductions of alien predators to breeding islands.