The people represented by the ends of the bell-curve are the most rare.
This could mean that if it's an iq curve the people at the ends have either a really high or really low iq etc.
The important part of the text is the following:
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"Their most important non-carrion food is fish, which they catch by
swooping down and grabbing fish that are near the surface of the water."
We know here that in order to survive, the Bald Eagle needs access to the water - and this water cannot be frozen. So the less ice cover there is, the more food it can obtain!
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Answer: a. native species
