Self-study
Babblers, a bird species, live in large cooperative groups. Each member attempts to defend the group by sounding a loud barklike call when it spots a predator, inciting the others to bark too. Babblers, however, are extremely well camouflaged and could usually feed safely, unnoticed by predators. These predators, indeed, generally become aware of the presence of babblers only because of their shrill barks, which continue long after most members of the group have been able to take cover and which signal the group's approximate location to the predators.
16.
Which one of the following, if true, would most help to explain the babblers' strange behavior?
a
Babblers fly much faster than the predators that prey upon them.
While this answer might explain a way by which babblers escape their predators, it does nothing to explain why the birds would make a noise that alerts the predators to their presence in the first place.
b
Babblers' predators are generally intimidated by large numbers of babblers.
This explains why it might be a good idea for babblers to make noise when predators are near. Predators are intimidated by large numbers of babblers, and only by hearing their collective call do predators become aware that there are many babblers nearby.
c
There is more than one type of predator that preys upon babblers.
The fact that there are multiple types of predators preying on babblers does nothing to explain why the babblers would want to call any predator’s attention to their presence.
d
Babblers' predators have very good eyesight but relatively weak hearing.
This may seem to mitigate the potential damage of the babblers’ loud call—maybe the predators can’t hear them well anyway?—but it does nothing to explain why the babblers would want to make any noise at all in the presence of predators.
e
Animals that live in close proximity to babblers are also preyed upon by the predators that prey upon babblers.
Even if the babblers’ call tells predators that other prey are nearby, it still also proves that the babblers themselves are there. Predators could easily decide to eat the babblers instead of the other animals, and this answer doesn’t explain why babblers would take that risk.