This species inhabits dense subtropical forest and warm temperate evergreen broadleaved forests, and is heavily dependent on mature forest. It feeds mainly on Camellia seeds, but is thought to take the seeds and fruit of other plants, and although it is mainly arboreal (subspecies nitens is however more terrestrial; O. Chikara in litt. 2020) it will also take fallen seeds from the ground (Gibbs et al. 2001). Diet analysis of the subspecies nitens shows seasonal variation and the consumption of both native and introduced plant species (Ando et al. 2013, Ando et al. 2016). Breeding occurs from February to September, and females lay a single egg in a tree-hole or amongst rocks (Gibbs et al. 2001). Subspecies nitens will breed from November, but may breed throughout the year (O. Chikara in litt. 2020).

Columba janthina is an uncommon and local resident in Japan, on small islands off southern Honshu, Shikoku and Kyushu, south through the Nansei Shoto islands to the Yaeyama Islands and the Izu Islands to the Ogasawara and Iwo Islands (BirdLife International 2001). It occurs locally on small islands off the south coast of South Korea, and it has been recorded (presumably as a vagrant) in eastern Russia, Shandong, mainland China and Taiwan (China). Although it is still relatively common on the Izu Islands, it has apparently declined there since the 1950s, and it is thought to have declined on Okinawa during the 1980s because of forestry activities. There are estimated to be only 30-40 individuals of subspecies nitens on the Ogasawara Islands, recently thought to be commoner with the population recovering following feral cat control, albeit the status of this subspecies on the Iwo Islands remains unknown (O. Chikara in litt. 2005, S.Chan in litt. 2005, O. Chikara in litt. 2020).

Conservation Actions Underway
Research into the genetic structure of the subspecies nitens suggests increased genetic diversity is needed in the captive population (Ando et al. 2014). It is declared a National Monument across the Ogasawara Islands (Baptista et al. 2020).

Conservation Actions Proposed
Survey to assess population size. Regularly monitor to determine population trends. Investigate its tolerance of degraded forest and the extent of hunting by local residents. Control hunting where possible, perhaps using awareness campaigns. Protect significant areas of intact forest on a number of islands across its range. Conduct research into the taxonomic status of its subspecies. Investigate the status of subspecies nitens on the Iwo Islands. Monitor dependence on introduced plants, and the potential affect of introduced plant eradication programmes on foraging abilities (Ando et al. 2016).