GRE Reading Comprehension
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Source: 1995
One explanation for the tendency of animals to be more vigilant in smaller groups than in larger ones assumes that the vigilant behavior—looking up, for example—is aimed at predators. If individuals on the edge of a group are more vigilant because they are at greater risk of being captured, then individuals on aver- age would have to be more vigilant in smaller groups, because the animals on the periphery of a group form a greater proportion of the whole group as the size of the group diminishes
. However, a different explanation is necessary in cases where the vigilant behavior is not directed at predators. J. Krebs has discovered that great blue herons look up more often when in smaller flocks than when in larger ones, solely as a consequence of poor feeding conditions. Krebs hypothesizes that the herons in smaller flocks are watching for herons that they might follow to better feeding pools, which usually attract larger numbers of the birds.
It can be inferred from the passage that the author of the passage would be most likely to agree with which of the following assertions about vigilant behavior?
- A The larger the group of animals, the higher the probability that individuals in the interior of the group will exhibit vigilant behavior.
- B Vigilant behavior exhibited by individuals in small groups is more effective at warding off predators than the same behavior exhibited by individuals in larger groups.
- C Vigilant behavior is easier to analyze in species that are preyed upon by many different predators than in species that are preyed upon by relatively few of them.
- D The term "vigilant," when used in reference to the behavior of animals, does not refer exclusively to behavior aimed at avoiding predators.
- E The term "vigilant," when used in reference to the behavior of animals, usually refers to behavior exhibited by large groups of animals.