The species of flora and fauna in the province is diverse on its north and east borders, which exhibit a shared ecosystem with the Caraballo mountains in the north and the Sierra Madre mountains in the east. The southeast areas are also known for its diverse fauna and flora due to the presence of the Minalungao National Park. The ceratocentron fesselii orchid, which can only be found in the Pantabangan-Carranglan Watershed Forest Reserve in Carranglan, is considered as one of the most critically endangered orchid species in the entire Southeast Asian region. It is endangered due to illegal gathering from the wild and due to the illegal black market trade. The forest reserve is also home to the endemic Rafflesia consueloae, which is the smallest rafflesia in the world and is found nowhere else. Philippine deer, Philippine warty pig, cloud rats, and other indigenous mouse species are also present in the province. In a recent activity, the presence of a Philippine Eagle couple was discovered in the Sierra Madre side of Nueva Ecija. The couple are now protected by the local government units in that area. Snakes, lizards, and various amphibian species are also present, especially in wetter months.