“The remaining land-birds form a most singular group of finches, related to each other in the structure of their beaks, short tails, form of body and plumage: there are thirteen species, which Mr. Gould has divided into four sub-groups. All these species are peculiar to this archipelago” - excerpt from the journal of Charles Darwin

Isla Daphne Major is a small island in comparison to other islands that make up the Galapagos island chain. The small size of the island allowed Peter and Rosemary Grant to track individual finches and make observations over a 40 year time period. The maps included in this lab represent data taken by Peter and Rosemary Grant between 1976 and 1985. In this lab, you will use the maps to create tables and graphs that give an overview of finch beak size on the island. Then you will make predictions and conclusions based on given scenarios.  

The map shows the location and beak size of medium ground finches on the island. Finches with “small” beaks (under 8mm) are marked by a circle. Finches with “midsize” beaks (8-9mm) are marked by a square. Finches with “large” beaks (over 9mm) are marked by a star. The medium ground finches on the map are all of one species, but show variation

 in beak size. Finches with larger beaks are more capable of cracking open larger seeds or nuts that survive after a drought. Finches with smaller beaks are more able to feed on smaller seedlings that grow abundantly

Copy the table below into your notebook. Use the map of Daphne Major in 

 to enter data into the table. Then make a bar graph with one bar for each category of beak size. Label x and y axis, title, and intervals. Take a screenshot to add the graph to your notebook. 

 In 1977, a drought hits the island and many of the small seedlings don’t survive. However shelled nuts and larger seeds are all over the island.

How would you expect the changes brought on by the drought to affect the survival of medium ground finches with different beak sizes on Daphne Major? Provide evidence and explain your reasoning.

to enter data into the table. Then make a bar graph with one bar for each category of beak size. Label x and y axis, title, and intervals. Take a screenshot to add the graph to your notebook. 

Does the data match what you expected? Explain.

Five years later, In 1983, heavy rain hits the island and vines with small seedlings sprout up everywhere. Harder shelled nuts and larger seeds are not as abundant. 

How would you expect these changes to affect the survival of medium ground finches with different beak sizes on Daphne Major? Provide evidence and explain your reasoning.

Section 3: The Island After Heavy Rainfall

Use the map of Daphne Major in 1985 to enter data into the table. Then make a bar graph with one bar for each category of beak size. Label x and y axis, title, and intervals.

The island of Daphne Major is the final stop on the tour and should provide an entry on the different characteristics of Darwin’s Finches discussed in the provided reading and video excerpt from HHMI Finches on Daphne Major

Darwin's Finches