Monarch Population Dynamics*

Try This!

Monarch Larva Monitoring Project

How many monarchs are there? What causes monarch numbers to change from year to year? Many complex factors interact that ultimately determine a population's size. To appreciate the scientists' challenge think the problem through for yourself!

On the chart below, list all the factors you can imagine that might cause high or low numbers at each stage of the monarch's annual cycle.

  • Begin with the breeding season. What factors might influence the number of eggs laid? What might cause the eggs or larvae to die? The adults? What might help greater numbers to survive?
  • Next consider the fall migration. (Review fall migration updates for ideas.) What causes monarchs to die during fall migration? What challenges can you identify?
  • Then consider mortality at the over-wintering sites. What are the causes of death there?
  • Finally, consider the spring migration. (Review spring migration updates for ideas.) What causes monarchs to die during spring migration? What challenges can you identify?

Keep and maintain this chart during your monarch study. How many ideas can you add over time?


Season in Mexico

"Population dynamics" is the study of changes in the number and composition of individuals in a population, and the factors that influence those changes

National Science Education Standards

Science as Inquiry
Ask a question about objects, organisms, events. (K-4)

Life Science
An organism's behavior patterns are related to the nature of that organism's environment, including the kinds and number of other organisms present, the availability of food and resources, and the physical characteristics of the environment. When environment changes, some plants and animals survive and reproduce, and others die or move to new locations. (K-4)

Science and Technology
People have always had questions about their world. Science is one way of answering questions and explaining the natural world. (K-4)