Counting Pikas in a Population

Counting Pikas in a Population

In this activity related to ecology, ecosystems and populations, you will learn a fun way to estimate the number of pikas in a population using a method that scientists actually use. As a way of integrating math into your learning, you can also make calculations to test and see if the method really works.

Suggested Age Range: Ages 10-17

Activity Time: 45-60 min

Prep Time:  5-10 min


Scientists are concerned about how a warming climate might be causing pika populations to decrease in number. How might we figure that out?  In order to answer that question, we first need to know how many pikas there are.  How do scientists, like Dr. Erica Garoutte count the pikas from year to year?  It is impossible to catch them all, so they have to estimate. 

One method that they use is called “the mark-recapture method”.  In this activity you will learn how to estimate the number of pikas in a population, using mark and recapture, just like a real scientist. You will also test to see if the method really works.


  • White beans ( or any large dried bean that can be marked on)
  • Paper or plastic bag (small is better)
  • Colored Markers (at least two colors)
  • Calculator

Learning Outcomes

In this activity you will:

  • View two videos that describe how scientists study pikas
  • Estimate the size of a population
  • Compare your estimate to the real count
  • Use a model to Test the “mark-recapture” method of counting a population
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