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Monarch Butterfly Tagging

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? We need data to answer these questions and we need your help! Only through the cooperative efforts of volunteer taggers will we be able to obtain sufficient recoveries and observations of the migration to answer these questions.

Because Monarchs have a certain "charisma" and a fascinating biology, and because it's fun to have an excuse to collect butterflies, this project is also a good way to introduce students to science and have them contribute to a scientific study. Through participation in this project we also hope to further interest in the conservation of habitats critical to the survival of the Monarch butterfly and its magnificent migrations.

To learn more about the "Monarch Watch" program, click here.

If you would like to become a volunteer butterfly tagger at Amistad National Recreation Area, contact our Resource Management Specialist:

David Larson
Amistad NRA
HCR 3, Box 5J
Del Rio, TX 78840
830-775-7491 x 204
David_Larson@nps.gov

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9/14/99:
Observed 3 Monarchs flying over park during a 2 hour period. These were the first observed at the park and was the beginning of the migration through Amistad.

9/16/99:
Observed 2 Monarchs flying over park during a 3 hour period.

9/22/99:
Observed 2 Monarchs flying over park during a 1 hour period.

9/30/99:
Migration of the Monarchs began to increase with the arrival of two cold fronts during the previous week. Flight monitoring was completed on the south side of the reservoir at Spur 454. Monarchs were migrating past a fixed observation point at approximately 10 butterflies per minute. These observations were completed between 0900 and 1000.

10/12/99:
Migration of the Monarchs slowed somewhat during the past week due to wind directions coming from the south. Today, the Monarchs are moving through the area in large numbers. Many roosting sites in the park were observed this morning. Morning temperatures were in the low 70's and Monarchs were easy to approach at roosting sites. Approximately 120 Monarchs were tagged for the Monarch Watch, which the University of Kansas is the sponsor. Tagging is being used to determine migration routes and life histories of this butterfly. Each tag contains an identifiable number and a return mailing address.

10/12/99:
Monarchs were counted near the Diablo East boat launch to determine migration rates. A fixed observation point was selected and it was found that Monarchs were migrating at approximately 100 per minute. These observations were completed between 1000 and 1030.

10/13/99:
Tagging of Monarchs continued, but warmer temperatures at sunrise made it difficult to approach the butterflies. By 0830, tagging was stopped because the Monarchs were too active. If the temperatures are lower, tagging can usually continue for another hour. Approximately 30 Monarchs were tagged for the Monarch Watch program. The roost were the monarchs were found only contained approximately 500 butterflies. The butterflies appear to prefer Huisache Trees (Acacia farnesiana) for roosting.

10/13/99:
Monarchs were counted near the 277 North Campground and were found to be migrating at approximately 10 per minute past a fixed point. Monarchs were also observed leaving roosts and landing in wet areas near the edge of the reservoir for mineral and water uptake.

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