The Philippine Deer (Cervus Mariannus Barandanus) is originally restricted to the Philippines but was later introduced into the Marianna Islands.

It was introduced to Guam by Spanish governor Mariano Tobias between 1770 and 1774 as a game species (William Edwin Safford 1905). Although scarce in its native range in the Philippines, it is overpopulated in many areas of Guam, posing serious threats to plant communities by overgrazing.

It can be found throughout most of the country.

Once common, it is now rare due to hunting and habitat loss except in very isolated areas. It can be recognized easily by its hoof prints (bakas ng usa) and by the off cut shoots that it leaves behind after feeding, which were frequently seen in cassava plantations in forest clearings on Patnanungan.

It stays in localities in the interior where there are extensive areas still covered with forests especially dense primary and secondary forests and up to about 1,500 meters above sea level in transition mid-mountain-mossy type forest.

The deer feeds in grassland areas preferably close to the edges of forests, and when disturbed, will immediately run towards the dense forest growth for cover.