Question 2

Ten-hectare tracts were too small for certain species of birds that needed to range over much larger tracts of land to find insects as a food source.

The study indicated that ten-hectare tracts could not adequately support certain species of birds, particularly those that rely on the movements of army ants to access their insect prey. As a result, these birds vanished from the isolated tracts, demonstrating the limitations of smaller areas for sustaining diverse species.

A) Ten-hectare tracts were large enough for several species of birds that continued to flourish as well as they had in much larger tracts of land.

This option is incorrect because the passage explicitly states that the ten-hectare plots did not support the birds that depended on army ants. Instead of flourishing, these birds left the area due to the lack of necessary resources.

B) Ten-hectare tracts were large enough for certain species of mammals to survive in, although the species' population size decreased because there was more competition among them for food.

This option is also incorrect. The passage does not discuss mammals in the context of ten-hectare tracts, nor does it mention competition among mammals. The findings specifically highlight the challenges faced by birds due to the size of the tracts.

C) Ten-hectare tracts were too small for certain species of birds that needed to range over much larger tracts of land to find insects as a food source.

This option is correct as it aligns directly with the findings of the study. The passage notes that the survival of bird species was compromised in ten-hectare plots due to their dependence on the movement of army ants for food, illustrating the critical size requirement for their survival.

D) Ten-hectare tracts were too small for certain species of mammals to survive in; after the mammals left the tract, three species of frogs that had relied on them to create wallows holding water also disappeared.

This option is incorrect because the passage does not mention any consequences for mammals or frogs in relation to the ten-hectare tracts. The focus is primarily on bird species and their dependency on army ants.

Conclusion

The correct answer, C, is supported by the study's findings that indicate ten-hectare tracts were inadequate for certain bird species that required larger areas to find food. All other options misinterpret the data or discuss irrelevant species, failing to connect accurately to the passage's central theme regarding the effects of tract size on biodiversity and species survival.