Beaks As Tools: Selective Advantage in Changing Environments

In this activity, students collect and analyze data from a hands-on model to discover why even slight variations in beak size can impact a bird’s ability to obtain food and survive.

in the 1970s and 1980s, medium ground finch populations in the Galápagos Islands experienced two major droughts. This activity simulates the food availability during these droughts and demonstrates how rapidly natural selection can act when the environment changes. In the model for this activity, students test which of two tools, which simulate different beak sizes, is better adapted to collect and “eat” seeds under various conditions. Students also watch clips from the short film The Beak of the Finch to provide context for what they will be modeling. 

The accompanying “Group Data Table” handout is for student groups to record their data. The optional “Class Data Table” spreadsheet can be used to compile data from multiple groups for plotting graphs and calculating descriptive statistics (mean and standard deviation).

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