Grassland songbirds often nest in the same grassland-wetland complexes as waterfowl, particularly in a certain part of those complexes, namely,...
GMAT Reading Comprehension : (RC) Questions
Grassland songbirds often nest in the same grassland-wetland complexes as waterfowl, particularly in a certain part of those complexes, namely, upland habitats surrounding wetlands. Although some wildlife management procedures directed at waterfowl, such as habitat enhancement or restoration, may also benefit songbirds, the impact of others, especially the control of waterfowl predators, remains difficult to predict. For example, most predators of waterfowl nests prey opportunistically on songbird nests, and removing these predators could directly increase songbird nesting success. Alternatively, small mammals such as mice and ground squirrels are important in the diet of many waterfowl-nest predators and can themselves be important predators of songbird nest. Thus, removing waterfowl-nest predators could affect songbird nesting success through subsequent increases in small-mammal populations.
In 1995 and 1996, researchers trapped and removed certain waterfowl-nest predators, primarily raccoons and striped skunks, then observed subsequent survival rates for songbird nests. Surprisingly, they observed no significant effect on songbird nesting success. This may be due to several factors. Neither raccoons nor striped skunks consume ground squirrels, which are important predators of songbird nests. Thus, their removal may not have led to significant increases in populations of smaller predators. Additionally, both raccoons and striped skunks prefer wetlands and spend little time in upland habitats; removing these species may not have increased the nesting success of songbirds in the uplands enough to allow detection.
According to the passage, which of the following is true about the role played by ground squirrels in the ecology of grassland-wetland complexes?
1. Passage Analysis:
Progressive Passage Analysis
| Text from Passage | Analysis |
|---|---|
| Grassland songbirds often nest in the same grassland-wetland complexes as waterfowl, particularly in a certain part of those complexes, namely, upland habitats surrounding wetlands. | What it says: Two types of birds (songbirds and waterfowl) live in the same areas, but songbirds prefer the higher ground around water. What it does: Introduces the basic setting and relationship between two bird species. Source/Type: Factual observation about bird habitat preferences. Connection to Previous Sentences: This is our starting point - establishes the foundation for everything that follows. Visualization: Picture a wetland area with water in the center, surrounded by higher grassland. Waterfowl (ducks, geese) use the whole area, but songbirds specifically choose the upland grass areas around the edges. Reading Strategy Insight: This is pure setup - memorize the basic geography and that these two bird types share space but with different preferences. What We Know So Far: Songbirds and waterfowl coexist in wetland complexes, songbirds prefer upland areas What We Don't Know Yet: Why this matters, what problems might arise from this arrangement |
| Although some wildlife management procedures directed at waterfowl, such as habitat enhancement or restoration, may also benefit songbirds, the impact of others, especially the control of waterfowl predators, remains difficult to predict. | What it says: When humans try to help waterfowl, sometimes it helps songbirds too, but when humans control predators that eat waterfowl, we're not sure how it affects songbirds. What it does: Introduces the central problem/question the passage will explore. Source/Type: Author's statement about management uncertainty. Connection to Previous Sentences: This builds directly on sentence 1's setup. Since the birds share space, management decisions for one species will affect the other. The word "Although" signals we're about to focus on a specific complication. Visualization: Think of wildlife managers as people trying to help waterfowl by: (1) improving habitat = usually helps both birds, (2) controlling predators = unclear effect on songbirds. Reading Strategy Insight: The phrase "difficult to predict" tells us the passage will explore this uncertainty. Don't worry about complexity yet - we're just being told what question the passage will answer. What We Know So Far: Birds coexist, some management helps both species, predator control effects are unclear What We Don't Know Yet: Why predator control effects are unclear, what research shows |
Why It's Right:
- Directly supported by the passage's explanation of why the experiment showed no effect
- Accurately reflects the specific predator-prey relationships described
- Captures the key distinction that was crucial to understanding the results
Key Evidence: "Neither raccoons nor striped skunks consume ground squirrels" combined with "small mammals such as mice and ground squirrels are important in the diet of many waterfowl-nest predators"
Why It's Wrong:
- The passage never mentions ground squirrels preying on waterfowl nests
- No information is provided about the relative importance of their predation on different types of nests
- This reverses the actual relationship described in the passage
Why It's Wrong:
- No information about ground squirrel population recovery rates is provided
- The passage doesn't discuss how quickly any populations compensate for predation
- This introduces concepts not addressed in the passage
Why It's Wrong:
- Completely contradicts the passage, which states ground squirrels prey on songbird nests
- No mention of ground squirrels preying on waterfowl nests anywhere in the passage
- Reverses the actual ecological relationship described
Why It's Wrong:
- The passage describes ground squirrels as predators, not as protectors of songbird nests
- No information supports the idea that ground squirrels control predation on songbirds
- This contradicts the passage's description of ground squirrels as songbird nest predators