Logical Reasoning

PT142 · S4 · Q26 Bird watcher: The decrease

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Bird watcher: The decrease in the mourning-dove population in this area is probably a result of the loss of nesting habitat.

Conclusion (probably)

Loss of nesting habitat is probably the reason for the decrease in the mourning-dove population in this area.

Evidence

Many mourning doves used to nest in the nearby orchards, but after they installed overhead sprinklers last year, the doves stopped building nests there.

Evaluate

Since the author is speculating the reason for a Curious Change (fewer mourning-doves), we can use our Curious Fact / Explanation mindset on this.

Curious Fact Why has the mourning dove population in this area decreased?

Author's Explanation The orchards installed overhead sprinklers last year, and the mourning doves stopped building nests in the orchard, and that's why we don't see as many in this area.

We can Strengthen this argument by ruling out an Alternate Explanation for the Curious Fact, or by boosting the Plausibility of the Author's Explanation.

What could be a different reason why there are fewer mourning-doves in the area? Maybe there are more predators than before. Maybe there is less food than before. Maybe the mourning-doves migrated away and many of them didn't make it back for some reason (if the mourning-dove is a non-migratory bird, then any ornithologist reading this is thinking, "Patrick, you're an idiot.)

How plausible is the author's explanation? Well I can see how overhead sprinklers would be a poor match for raising babies in a nest. But does this one change in the orchards really explain their decrease in the area? Couldn't they just make their nests somewhere besides the orchard, but still in this city?

Goal

We want an answer that rules out a different cause of fewer mourning-doves in the area, or we want an answer that adds some plausibility to the storyline that losing their nesting habitat in the orchards is the catalyst for seeing fewer of them in the area.

26.

Which one of the following, if true, most strengthens the argument?

  1. Mourning doves were recently designated

    Weakens

    This provides an Alternate Explanation. It's suggesting, "the doves aren't decreasing in population because they're losing habitat; it's because they're getting hunted".

    1% picked this

  2. Correct

    The trees in the nearby

    Why this is right

    We love how strong (i.e. impactful) this answer is with the only. If the trees in these orchards are their only eligible nesting site, then that adds a lot of plausibility to the author's story that loss of habitat (caused by the installation of overhead sprinklers at the orchard) is the reason for the mourning-dove's declining population in the area. According to this answer, there is no other available habitat. We know the doves were previously using the orchards, and now that they can't, there's nowhere in the area for them to live.

    Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.

    75% picked this

  3. Blue jays that had nested

    No Impact

    This would sound like a More Cause, More Effect strengthener (i.e. provides more data points of cause/effect going hand in hand), if we were trying to strengthen the idea that "the sprinklers caused the doves to leave the orchard". But we already accept that the sprinklers caused the doves to leave the orchard. What we're analyzing in this question is whether "leaving the orchard, because of the sprinklers, is the reason that the doves have started to leave the area (the overall city/region)" If this answer choice said that "blue jays that had nested in the orchards are also decreasing in population in the area since the sprinklers were installed", that would be a strengthener.

    20% picked this

  4. Many residents of the area

    Too Weak

    "Many" and "appropriate" really water down the impact of this. If residents of the area are providing mourning doves with food, then that would rule out the idea that mourning doves are leaving the area because the food source has dried up. But, the fact that "many (at least 10) residents are filling their bird feeders with appropriate seeds" isn't taking us that close to the idea we'd want of, "the mourning doves don't have to worry about finding food in this area". Also, there's no way in a head-to-head between this answer and the correct answer that we could say the effect this has (of slightly ruling out the possibility that mourning doves can't find food) beats the effect the correct answer has (saying that orchards were the only possible habitat in the area).

    3% picked this

  5. Mourning doves often nest in

    Too Weak

    "Often" is not that impressive a quantifier to begin with (it could still be less than 50% of the time). And we already knew that some mourning-doves nest in fruit trees, because trees at orchards are by definition fruit trees, I believe. So this adds almost nothing to the facts we already had.

    1% picked this

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