Read Group Living Through Trade-offs
Read group-living graphs as a balance of feeding opportunity, vigilance, competition and predation risk.
Group Living and Predation Risk is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Track the flock time budget
As flock size rises, each bird can spend less time scanning because vigilance is shared. Feeding can first increase as scanning falls, then decrease when crowding and competition matter. Fighting rises as more birds compete. Therefore the three curves are scanning, feeding and fighting: choose C.
Separate group costs from group protection
A larger group becomes more conspicuous, so the relative probability of attack can rise. Shared vigilance and predator confusion reduce attack success, while dilution sharply reduces the chance that any one individual is attacked. Match those mechanisms to the direction of each curve before selecting an option: choose A.
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- ✓Shared vigilance lowers individual scanning time.
- ✓Crowding can turn a feeding benefit into a cost at larger flock sizes.
- ✓Conspicuousness can raise attacks; confusion and vigilance lower attack success.
- ✓Dilution concerns the risk to one individual, not the group as a whole.
Do not assume every benefit rises with group size. Read the axis and decide whether a curve measures attack frequency, attack success, or an individual’s risk.
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