[citation needed] Since O. n. nigriplantare is almost locally extinct on Pitt Island as a result of introduced mammals,[1] the presence of introduced mammals on Chatham Island might have resulted in the local extinction of O. n.

[citation needed] On vegetated islands, O. n. nigriplantare inhabits grassland and shrub habitat, but it also occurs on marine rock stacks with sparse vegetation.

[1] Substantial morphological variation (body size, colour and colour pattern) is evident within O. n. nigriplantare,[2][1] potentially indicating morphological evolution following its colonization of the Chatham Islands.

Indeed, O. n. nigriplantare (up to 91 mm Snout to Vent Length; SVL) has a substantially larger body size than Oligosoma nigriplantare polychroma (up to 77 mm SVL).

[5] This pre-dates the emergence date for the Chatham Islands, but indicates that O. n. nigriplantare colonized the Chatham Islands via overwater dispersal on a single occasion.