Indigenous trees include the mangrove, rubber, dogwood, mahogany, cedar, and walnut; pine and oak are found in the northern mountainous region. Varieties of tropical fruit, numerous medicinal plants, and balsam, a medicinal gum, grow in the country. Native fauna (greatly reduced in recent decades) includes varieties of monkey, jaguar, coyote, tapir, and armadillo, along with several kinds of parrots and various migratory birds. Fish, both freshwater and saltwater, turtles, iguanas, crocodiles, and alligators abound. Both venomous and nonvenomous snakes, the latter including the boa constrictor, are common in El Salvador.