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.What legitimate factors might lead a scientist to do an imperfect version of an experiment, such as using chicken eggs as a stand-in for gull eggs? (Check all that apply.)A) Because the scientist doesn't care about proper procedureB) The perfect experiment is too expensive.C) The perfect experiment would harm the study species.D) To quickly get preliminary data for a grantE) IgnoranceF) The perfect experiment would take too much time.

What will be an ideal response?

Answer 1

B, C, D, F

Clarify Question
• What is the key concept addressed by the question?
        o Need to understand the process of designing an experiment and what variations the design can take without impacting the results.
• What type of thinking is required?
        o This is an evaluate question. You are being presented with several potential justifications for an experimental design that does not perfectly replicate the natural situation. You need to judge whether each choice is or is not a valid justification.

Gather Content
• What do you already know about experimental design? What other information is related to the question? 
        o This question comes from the section of the textbook that discusses behavioral ecology. There is more than one correct answer. This question is not directly about behavioral ecology, rather, it concerns experimental design. The ideal animal behavior experiment would occur in the wild and would replicate natural conditions as closely as possible. This is always the most desirable because the data the experiment generates would be much more valid. The question is asking you to pick out a valid reason why a researcher would conduct an experiment that doesn't exactly replicate the natural situation (ex. using chicken eggs instead of sea gull eggs when testing egg predation rates).

Choose Answer
• Given what you now know, what information is most likely to produce the correct answer?
        o The only incorrect answer is the choice "because the scientist doesn't care about proper procedure", this is clearly wrong. Getting an experiment to perfectly match natural conditions is always the best option, but sometimes that just isn't possible.

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 you able to select all of the correct justifications? The key to this evaluate question is to see that perfection in experimental design is always ideal but not always possible.