Every fall Croton's jays migrate south. The jays always join flocks of migrating crookbeaks with which they share the same...
GMAT Critical Reasoning : (CR) Questions
Every fall Croton's jays migrate south. The jays always join flocks of migrating crookbeaks with which they share the same summer and winter territories. If a jay becomes separated from the crookbeaks it is accompanying, it wanders until it comes across another flock of crookbeaks. Clearly, therefore, Croton's jays lack the navigational ability to find their way south on their own.
Which of the following, if true, most strengthens the argument above?
Passage Analysis:
| Text from Passage | Analysis |
| Every fall Croton's jays migrate south. |
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| The jays always join flocks of migrating crookbeaks with which they share the same summer and winter territories. |
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| If a jay becomes separated from the crookbeaks it is accompanying, it wanders until it comes across another flock of crookbeaks. |
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| Clearly, therefore, Croton's jays lack the navigational ability to find their way south on their own. |
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Argument Flow:
The argument starts with basic facts about jay migration, then shows how jays consistently depend on crookbeaks for travel. It strengthens this dependency by showing what happens when jays get separated - they don't continue alone but search for more crookbeaks. From this pattern of behavior, the author concludes that jays must lack independent navigation skills.
Main Conclusion:
Croton's jays lack the navigational ability to find their way south on their own.
Logical Structure:
The evidence shows a consistent pattern: jays always travel with crookbeaks and never attempt to continue alone when separated. The author argues this dependency proves they can't navigate independently - if they could find their way alone, they wouldn't need to search for crookbeaks when separated.
Prethinking:
Question type:
Strengthen - We need to find information that makes the conclusion more believable. The conclusion is that Croton's jays lack navigational ability to find their way south on their own.
Precision of Claims
The argument makes specific claims about jay behavior: they 'always' join crookbeaks, they migrate 'every fall', and when separated they 'wander until' finding another flock. These are absolute frequency and activity claims that we need to respect.
Strategy
To strengthen the conclusion that jays can't navigate independently, we need evidence that supports this inability. We can look for:
- evidence that jays actually get lost when alone
- evidence that crookbeaks have superior navigation skills that jays depend on
- evidence that rules out alternative explanations for why jays seek out crookbeaks (like safety or food rather than navigation)
This choice tells us that jays lay eggs in crookbeak nests after southern migration. While this shows another relationship between the species, it doesn't strengthen the argument about navigational ability. Jays could still lack navigation skills or have excellent navigation skills - this breeding behavior is irrelevant to the question of whether they can find their way south independently.
Information about crookbeaks' relatives not migrating at all has no bearing on whether Croton's jays can navigate independently. The navigational abilities of completely different species (crookbeaks' relatives) tells us nothing about jays' abilities. This is irrelevant to strengthening the conclusion.
This significantly strengthens the argument. If jays also travel with Tattersall warblers during spring migration, this shows a consistent pattern - jays always depend on other birds for navigation in both directions and across seasons. This rules out the alternative explanation that jays choose crookbeaks for reasons other than navigation (like food or protection). The pattern of dependency with different species strongly supports that jays fundamentally lack navigational ability.
Knowing that other species sometimes join crookbeak flocks doesn't tell us anything specific about Croton's jays' navigational abilities. Whether other birds join these flocks is irrelevant to whether jays specifically can navigate on their own. This doesn't strengthen the argument about jays.
The fact that crookbeaks migrate north before jays in spring doesn't strengthen the argument about jays' fall navigation abilities. This timing information doesn't provide evidence about whether jays can or cannot navigate independently. If anything, it suggests jays might migrate separately in spring, which could potentially weaken the argument rather than strengthen it.