 Given the geological history of the Chatham Islands, it is assumed that "O. n. nigriplantare" previously occurred on Chatham Island; however, there are no fossil records or historical reports of "O. n. nigriplantare" on Chatham Island.Since "O. n. nigriplantare" is almost locally extinct on Pitt Island as a result of introduced mammals, the presence of introduced mammals on Chatham Island might have resulted in the local extinction of "O. n. nigriplantare".On vegetated islands, "O. n. nigriplantare" inhabits grassland and shrub habitat, but it also occurs on marine rock stacks with sparse vegetation.