The Northern Sierra Madre Natural Park is within the Sierra Madre Biogeographic Zone which lies along the eastern side of Central Luzon. It is considered as one of the most important protected areas system in the Philippines owing to the myriad of rare and endangered species of flora and fauna that it supports. They include the Philippine eagle, giant golden-crowned flying fox, Philippine eagle-owl, Isabela oriole, green sea turtle, loggerhead sea turtle, hawksbill sea turtle, Philippine crocodile and dugong. It is also home to the green-faced parrotfinch and the Northern Sierra Madre forest monitor.