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The Extraordinary Travels of a Tagged Monarch

As monarchs pass over your head on their way to Mexico you probably wonder--where will those butterflies be in a few hours, days, or weeks? How fast do monarchs migrate?

Mark Garland, Senior Naturalist of the Audubon Naturalist Society, made some fascinating observations while tagging monarchs on Fisherman Island, VA. (Find Fisherman Island just off the southern tip of the Delmarva Peninsula, guarding the north end of the mouth of the Chesapeake Bay.)

Of the 1,500 monarchs he captured and tagged during two fall seasons, 5 butterflies had already been tagged to his north in Cape May, New Jersey. The straight line distance from Cape May to Fisherman Island is about 210 miles.

  • Three were caught 8 days after they'd been tagged,
  • One had made the trip in less than 48 hours,
  • and one had had an even more remarkable journey:

    "That monarch was tagged at 1 p.m. October 6, 1999, in Cape May, New Jersey. I netted it the next day, at 4:56 p.m. October 7, 1999, on Fishermans Island, VA," said Mark.

    Let's reason this through, and estimate how fast that butterfly may have traveled. Here are some helpful facts:
  • Monarchs aren't thought to fly in the dark. Sunset was 6:35 pm in New Jersey on October 6th . Sunrise was 7:01 am in Virginia on October 7th
  • Monarchs don't fly until they're warm enough. The monarch's flight threshold is about 13 degrees C (55 F). (Flight threshold means that this temperature, 13C, is the lowest temperature at which monarchs can fly.) In order to fly WELL, with lots of control, monarchs need to attain thoracic temperatures in the upper 20s or even 30s--pretty close to the temperatures that warm-blooded mammals run. We don't have temperature data from that October day, so you'll have to estimate during which hours the butterfly flew.
  • Keep in mind the behavioral observations people have made at roost sites: Monarchs generally settle in an hour or two before sunset. In the morning, they don't leave until the sun hits the trees and/or begins to warm the air around them--a good hour or two after sunrise.

So how fast do you think the tagged monarch traveled?

Try This! Journaling Questions
  • In how FEW hours might the monarch have traveled the 210 miles? (In your answer, explain why you counted the hours the way you did.)
  • Using the number of hours you calculated above, how many miles per hour might the monarch have traveled, on average?
  • When your calculations are done, click here to check them against ours.

National Science Education Standards

Science as Inquiry
Use math in all aspects of scientific inquiry. (5-8)

Scientists develop explanations using observations (evidence) and what they already know about the world. Good explanations are based on evidence from investigations. (K-4)

Physical Science
An object's motion can be described by tracing and measuring its position over time. (K-4)

Earth Science
Weather changes from day to day and over the seasons. Weather can be described by measurable quantities, such as temperature, wind direction and speed, and precipitation. (K-4)

National Geography Standards

The World in Spatial Terms
How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information.

National Math Standards

Numbers and Operations
Compute fluently and make reasonable estimates.

Apply appropriate techniques, tools, and formulas to determine measurements.

Problem Solving
Solve problems that arise in mathematics and in other contexts.

Reasoning and Proof
Select and use various types of reasoning and methods of proof.

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