Amistad National Recreation Area - Monarchs

Amistad National Recreation Area by National Parks Service

Monarch butterflies migrate south because they cannot survive a long cold winter in the north. The Monarchs' migration is driven by seasonal changes. Day length and temperature changes influence the movement of the Monarch as well.

Amistad National Recreation Area (NRA) is located along the migration route of the Monarch butterfly Danaus plexippus. The Monarch butterflies' life history contains three to four generations per year. The last generation migrates in the fall from the northern United States and Canada to winter in central Mexico. This generation lives as long as eight months, spending approximately 5 of those months in a semi-hibernation state in forested mountains of Mexico.

Why Tag Monarchs?

How do Monarchs find the overwintering sites each year? No one really knows. Somehow they know their way, even though the butterflies returning to Mexico or California each fall are several generations of the butterflies that started the previous spring. How does their homing system work? Many questions remain unanswered about the fall migration of the Monarch population east of the Rocky Mountains. How do the Monarchs move across the continent, i.e. do they move in specific directions or take certain pathways? How is the migration influenced by the weather and are there differences in the migration from year to year?