Birds on Both Sides of a Lock and Dam

The water prior to (east of) the Lock and Dam 15 in Davenport, Iowa, is deep and pooled. As it passes through the dam the moving water below the dam stirs up many nutrients. This churning of the water makes more food available for fish. Another feature is that many fish are temporarily stunned as they pass through the dam. Both of these situation cause the water below the dam to be a good location for fish-eating birds and fishing. This is demonstrated in the video showing no birds or fishing people before the dam and quite a few of them after the dam.

• Why are there so many birds on one side of the dam and not the other?

• What is happening on the one side of the dam that is attracting the birds there?

Students could:

• Explore how this phenomena is an example of density dependent limiting factors. 
• Watch the video, discuss what they observe, then make possible explanations for their questions. 
• Could count the numbers and types of birds on each side of the dam. They can expand to use bird count data in the area from the Audubon Christmas count and construct population trends to explain factors that are affecting the biodiversity in their areas. Students can select their region and get data from the bird count for several years. They could then construct their own graph and analyze it.

• Middle Tennessee State University | Limiting Factors of the Cedar Glade: This is a limiting factor activity with a data set for owls and mice in Tennessee. This gives the students the opportunity to analyze more data.
• Audubon Christmas Bird Count: This site contains 121 years of data from the longest-running bird count in the nation. 
• Project Wild | Oh Deer!: This site contains a data set of Indiana bats that students can graph and analyze, as well as information about the “Oh Deer!” population activity.