Monarch Butterfly Biosphere Reserve
The Monarch Butterfly Biosphere Reserve (Spanish: Reserva de Biosfera de la Mariposa Monarca) is a World Heritage Site that contains most of the wintering places for the eastern population of the monarch butterfly. The reserve is located in the Trans-Mexican Volcanic Belt pine-oak forests ecoregion, on the border of Michoacán and the State of Mexico, 100 km (62 miles) northwest of Mexico City. Millions of butterflies arrive in the reserve each year.