Population Dynamics


Dr. Smith uses ecological census techniques to estimate the size of rodent and beetle populations at her study sites. She sets baited traps, and then captures, marks (hair dye for rodents, pin prick for beetles), and releases organisms. By recording the proportion of marked to unmarked individuals in each sample, Dr. Smith can estimate total population size. In this assignment students will learn more about the mark-recapture method, and how to calculate population estimates using mathematical equations. This new information will help students investigate how populations change over time.

*This assignment was created by Dr. Kelsey Robson at Idaho State University. Please contact Dr. Robson at robskels@isu.edu for the answers to the assignment questions and the completed data sets.

ESA Learning Goal:

How do populations change over time?


  1. Summarize rodent census data and answer questions about the graph of change in rodent biomass over time.

  2. Summarize beetle census data and answer questions about the graph of change in minimum # known alive over time.

  3. Answer questions based on the figures from the Smith and Merrick (2001) publication. 


  1. Analyze rodent census data in Excel. Use the Schnabel method to estimate population size.

  2. Analyze beetle census data in Excel. Use an index to estimate population size.

  3. Create graphs using the Tableau software.

  4. Read the abstract and examine figures from Smith and Merrick (2001).