Part B – Experimental design: Choosing a study organism Based on the hypothesis that DDT was causing a decline in fish-eating bird populations in the United States, a group of scientists predicted that the amount of DDT in bird eggs was correlated with the thickness of the egg shells. For their experimentthey planned to visit a number of fish-eating bird populations and take 1 egg from 70 nests. In the laboratory, they would open the eggs to measure the concentration of chemicals such as DDT. They would also measure the thickness of the egg shells. The researchers had to decide which species of birds they would use in their study. Choosing the proper study organisms is very important because the species must be appropriate for the experiment, and practical to work with. Imagine that it is 1960, and the scientists have asked you to help them select the species of bird for use in their research. They have narrowed their options down to 6 species, Drag a check mark to species that would be good to use in the study, there may be more than one. Drag an X to species that would not be good for the study. BALD EAGLE Haliaestus leucocephalus AMERICAN GOLDFINCH Spinus trist is BROWN PELICAN Pelecanus accidentalis Average wingspan 2.1 m Average wingspan: 0.2 m Average wingspan 2.1 m Diet: Fish Diet Diet: Seeds Fish Endangered? Yes Endangered? No Endangered? No Location: North America Location: North America Location coasts of the Americas N Eggs per clutch Potwzk/Shutterstock 1-4 Eggs per clutch Eggs per clutch 2-4 Steve Byland/Fotolia Nagel Photography OSPREY Pandion halactus SECRETARY BIRD Sagittarius sepentarius EMPEROR PENGUIN Aptenodytes forsteri Average wingspans 1.5 m Average wingspan: 2.1 m Average wingspan ; 0.8 m Diet: Diet Fish Diet: Fish Endangered? No Endangered? No Location: coast of North America Location: Central and Southern Africa Location Antarctica Eggs per clutch 2-4 Eggs per clutch S.D. Bower/Fotolia Martin Kemp/Fotolia Eggs per clutch 2-3 San Martin win