5. Niko Tinbergen (1907-1988) was a Swedish Ethologist (animal behaviorist) famous for studying
that are covered with dark brown spots. However, the inside of the egg is white in color. Tinbergen
gull (Larus ridibundus). Black-headed gulls build nests of twigs on the ground and lay light brown eggs
far from the nest, where they are left. Since this behavior required expending energy and time that could
noticed that adult gulls pick up the eggshells shortly after a chick has hatched, and fly them to a location
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
White Eggs
Natural Eggs
69
68
cientific Method
Eggs Taken by Predators
43
a. Do the results of this experiment support the hypothesis? Why, Why not?
d. Identify the experimental and dependent variables
13
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. Indentify the experimental and dependet variables