Reference no: EM132441435
Niko Tinbergen (1907-1988) was a Swedish ethologist (animal behaviorist) famous for studying animals in their native habitats. One of his classic experiments involved a bird called the black-headed gull (Larus ridibundus). Black-headed gulls build nests of twigs on the ground and lay light brown eggs that are covered with dark brown spots. However, the inside of the egg is white in color. Tinbergen noticed that adult gulls pick up the eggshells shortly after a chick has hatched, and flies them to a location far from the nest, where they are left. Since this behavior required expending energy and time that could have been spent feeding and protecting the chicks, Tinbergen wanted to know why the birds did this.
Problem: Why do black-headed gulls remove eggshells from the nest?
Hypothesis: The white interior of the shell is not camouflaged and attracts predators to the nest. Therefore, the gulls remove the shells to decrease predation.
Test: Tinbergen and his co-workers collected gull eggs and painted 69 of them white and left 68 of them with their natural color. (Statistically, these numbers are close enough to be considered equal.) The researchers then scattered the eggs next to a gull breeding area and observed from a nearby blind. Predation rates were recorded for white versus natural colored eggs.
Data:
Original Number of Eggs Eggs Taken by Predators
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White Eggs
69 43
Natural Eggs
68 13
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a. Do the results of this experiment support the hypothesis? Why, Why not?
b. Are you 100% sure (without a doubt) that your hypothesis is correct? (Is it proven?)
c. If you were working with Tinbergen, what would you suggest be done next?
d. Identify the independent and dependent variables.