Population Estimation
About the Module:
In this module, students explore different methods for estimating the population sizes of squirrels. Tracking populations is a key skill for any student interested in a career in ecology, conservation or management. In this activity, students practice estimating the size of a single population using multiple methods (strip censuses, scat counts, distance sampling, camera traps, and simulated or real mark-recapture methods). They can then compare the results that they obtain with each method and consider how the assumptions of each model (e.g., random use of habitats and animal behavior) bias the results. Finally, students submit their data to our national dataset that aggregates observations from multiple institutions. They can then access and analyze the freely available national database, which allows students to explore these questions across a broader variety of habitats and species than would be possible at a single institution.
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Although the data collection protocols are prescribed (indeed, a key goal of the activity is teaching students how to perform each method), students are central to developing questions to ask with the national dataset, including how each technique performs in different habitats or for different kinds of species (e.g., nocturnal vs. diurnal animals). Extensions of this activity then guide students to enumerate the advantages and disadvantages of each method in different contexts, and to select the most appropriate method for a given scenario.
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This module is probably most relevant to elective courses in ecology, evolutionary and organismal biology programs; however, the activity could also be easily adapted for a broader range of students (e.g., in an introductory ecology course). In addition, because of the national dataset, students that are not able to collect their own data (e.g., due to course limitations or lack of appropriate species near an institution) can still participate in the analysis and extension aspects of this activity.
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