Tinbergen observed that after gull nestlings hatch, the parents remove the eggshells from the nest. To understand why (ultimate causation), he painted chicken eggs to resemble gull eggs, which had camouflage coloration to allow them to be inconspicuous against the natural background. He distributed them throughout the area in which the gulls were nesting, placing broken eggshells with their prominent white interiors next to some of the eggs. As a control, he left other camouflaged eggs alone without eggshells. He then noted which eggs were found more easily by crows. Because the crows could use the white interior of a broken eggshell as a cue, they ate more of the camouflaged eggs that were near eggshells. Tinbergen concluded that eggshell-removal behavior is adaptive:

Question

it reduces predation and thus increases the offspring's chances of survival.Rank these experiments from worst to best to study why gulls remove broken eggshells from their nests.____ Place broken eggshells near brown chicken eggs painted with dark brown spots, and record predation by crows.____ Place broken eggshells near real gull eggs, and record predation by crows.____ Place broken eggshells near brown chicken eggs, and record predation by undergraduate students acting as "predators."____ Place broken eggshells near brown chicken eggs painted with dark brown spots, and record predation by undergraduatestudents acting as "predators."____ Place broken eggshells near white chicken eggs, and record predation by undergraduate students acting as "predators."

What will be an ideal response?

Answer 1

4 Place broken eggshells near brown chicken eggs painted with dark brown spots, and record predation by crows.
5 Place broken eggshells near real gull eggs, and record predation by crows.
2 Place broken eggshells near brown chicken eggs, and record predation by undergraduate students acting as "predators."
3 Place broken eggshells near brown chicken eggs painted with dark brown spots, and record predation by undergraduate
students acting as "predators."
1 Place broken eggshells near white chicken eggs, and record predation by undergraduate students acting as "predators."

Clarify Question 
• What is the key concept addressed by the question?
         o Deducing what is needed to design an experiment to study why gulls remove broken eggshells from their nests. 
• What type of thinking is required?
         o This is an evaluate question. You are being presented with 5 different experimental designs. The experiments are trying to generate data concerning the removal of eggshell fragments from nests. You need to rank the designs from worst to best. 

Gather Content 
• What do you already know about the gull behavior of removing broken eggshells from their nests and what is involved in planning an experiment? What other information is related to the question?
         o This question comes from the section of the textbook that discusses behavioral ecology. There are 2 components of the experimental designs that differ. The first is the use of humans to simulate predation versus using actual nest predators (crows). The second component is the eggs: the options are white chicken eggs, brown chicken eggs, brown chicken eggs with spots painted on them, and finally actual gull eggs. 

Choose Answer 
• Given what you now know, what information is most likely to produce the correct answer?
         o Any experiment must try and replicate the natural conditions as close as possible. In fact, doing the experiment in nature (with actual predators and actual gull eggs) is by far the best choice. Using real nest predators is much better than using humans as models. The brown-spotted chicken eggs are a much better simulation of the real thing. 

Reflect on Process 
• Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
         o Were your rankings correct? The key to this question is to rank the designs from most similar to what is found in nature to least similar to the natural situation.