Migratory North American songbirds like the Tennessee warbler and the Baltimore oriole depend on the dense tree cover that has long been a feature of South American coffee plantations. This tree cover is being eliminated. Yet a population decline among Tennessee warblers is being attributed to a temporary drop in the population of spruce budworms, the warbler’s favorite North American prey. Baltimore orioles, however, do not eat budworms and are also experiencing a population decline.
The information above, if accurate, could best serve as part of an argument thatThe passage suggests that the Tennessee warbler’s decline may not be caused only by the temporary drop in spruce budworms. Baltimore orioles are also declining, even though they do not eat budworms.
That points to a shared cause, namely the loss of South American tree cover, which affects both birds during migration or wintering.
A. the decline in the numbers of the Tennessee warbler is responsible for the decline in the population of the spruce budworm
This reverses the suggested relationship. The passage says the budworm decline is being used to explain the warbler decline, not the other way around.
B. the Tennessee warbler population will not rebound when the spruce budworm population returns to normal
This is correct. If the warbler decline is at least partly caused by loss of tree cover, then the population may not recover simply because the budworm population returns to normal. The budworm drop may be only a
partial or mistaken explanation.
C. variations in the population of the Tennessee warbler influence the numbers of the Baltimore oriole
This is unsupported. The passage gives no reason to think one bird’s population affects the other’s.
D. the population of Tennessee warblers can reasonably be expected to increase in the near future
This is not supported. The passage gives a reason to doubt that the decline is only temporary.
E. the population of Tennessee warblers is declining less sharply than the population of Baltimore orioles
This is unsupported. The passage says both are declining but gives no comparison of how sharply.
Answer: (B)