The latter animals reached Mindoro from Luzon, or possibly in some cases Greater Negros-panay. The large Mindoro forest mouse, with its close relationship to the Luzon montane forest mouse, probably falls into the group of animals that reached the island from Luzon. The large Mindoro forest mouse has been found at three different sites in the municipality of San Teodoro, on the North flank of Mount Halcon. These sites are located at altitudes between . There is a good possibility, however, that the large Mindoro forest mouse also occurs on other mountains on Mindoro, especially on the northern part of the island, which is home to large areas of undamaged cloud forest. The lowest forests in which the large Mindoro forest mouse has been found, at some above sea level, are mostly between in height, with the very tallest reaching . The dominant species of tree are from the genera "Leptospermum flavescens", "Tristaniopsis" and "Lithocarpus", from the families Myrtaceae and Fagaceae. These very humid forests have a dense understory vegetation, which consists, amongst other plants, of mosses, tree ferns and species of "Pandanus". At higher altitudes (between ) the forest is dominated by bamboo, while the only tree species present is "Agathis philippinensis". Here, vegetation reaches a height between . There are many smaller plants present, such as ferns, orchids and species of "Pandanus". The forest floor is covered with a layer of leaves with a thickness between . Nothing is known with any certainty about the behaviour of the large Mindoro forest mouse. The long snout, small upper incisors and long lower incisors suggest that the animal feeds on soft invertebrates, but this is not certain. Furthermore, the long tail and elongated hind feet with well-developed claws point towards a climbing lifestyle. Very little is also known about the animal's procreation habits. A female specimen was found to carry three embryos. Another female had a swollen uterus, and testicles were visible in several of the male specimens.