GMAT 考满分题库

The arctic curlew, a once common wading species in the tundra, has reached endangered status in a mere few decades. Those who account for the sudden loss of the bird do so in terms of either pollution or climate change. Fagen notes how hydrocarbons from oil tankers have increased in a proportion commensurate with the decline in the number of arctic curlew. He believes that the birds not only ingest hydrocarbons while wading in polluted water but that they also feed on worms and small fish that themselves have accrued modest amounts of hydrocarbons. Miller, on the other hand, believes that climate change alone can account for the depletion of the arctic curlew. She argues that since many of the areas in which it once fed no longer provide adequate sustenance, the bird has been forced to change migratory paths and must land in a foreign ecosystem where it is unable find adequate nutrition.

Both theories, however, are somewhat correct but not in a way that either Fagen or Miller would have likely anticipated. The theory positing that the hydrocarbons birds ingest affect their ability to navigate contains elements relating to both climate change and pollution. For example, when a curlew ingests tainted fish, its ability to navigate for several hours afterwards is diminished and it will often veer from its traditional path. Where at one point such deviations would not have affected the bird's ability to forage, climate change has resulted in a significant diminishment of areas capable of providing sufficient sustenance for the arctic curlew. As a result, it often succumbs to starvation.