An insectivorous bird has the choice of eating (1 ) meadow beetles, which are abundant and large but expose the bird to hawk predation, (2 ) under-a-rock beetles, which are large and fatty but hard to obtain, or (3 ) under-a-leaf beetles, which are easy
to obtain but small. The bird has nestlings to feed. As an optimal forager, it will
A) concentrate on under-a-leaf beetles because they are easy and safe.
B) concentrate on under-a-rock beetles because they are energy-rich.
C) eat one kind of beetle at a time (first under-a-leaf, then meadow, then under-a-rock), switching to a new kind when the old kind becomes scarce.
D) eat all three kinds of beetles, balancing the energy spent and the risks incurred against the energy gained.
Answer: D
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