Multiple choice

In maintaining migrating animals would need a fantastic map sense to determine geographic position by celestial navigation, the author intends to express _____________.

Directions: Answer the question based on the following passage.

It is ironic that many of us view tropical birds as strange, and perhaps even bizarre, when they vastly outnumber temperate-zone species. The paradox hits home when many aspects of birds we take for granted are, instead, products of a temperate-zone bias—due to the geographic distribution of people who study birds.

The capability of over-water migrants to travel on course is an occult phenomenon. Birds, bees and other species can keep trail of time without any sensory cues from the external world, and such “biological clocks” clearly contribute to their “compass sense.” To find north, for instance, they can use the position of the Sun or stars, along with the time of day, But compass sense alone cannot elucidate how birds navigate the ocean: after a flock traveling east is blown far south by a storm, it will presume the proper northeasterly course to recompense. Like any good pilot, the birds carry a compass. Recent research suggests that cells in the bird's head contain magnetite, an iron oxide crystal that aligns with magnetic north like a tiny compass needle. Scientists think these cells may serve as receptors that send directional information to the brain. Many other animals apparently also have such cells: Magnetite has been found in the heads of migratory fish, sea turtles and humpback whales. Of all the wildlife navigators, birds so far are the best studied. Perhaps, some scientists thought, migrants determine their geographic position on Earth by celestial navigation, almost as human navigators use stars and planets, but this would require of the animals a fantastic map sense.

Researchers now know that some species have a magnetic sense, which might allow migrants to determine their geographic location by detecting variations in the strength of the Earth’s magnetic field.

The researchers found that the birds' ability to select the correct feeder was significantly impaired if the birds had small magnets attached to their beaks. The scientists suggest this is because magnetite, an iron-rich crystal with magnetic properties, is found inside the birds' beaks.

  1. praising the map sense of the migratory birds

  2. certainty that the phenomenon of migration will remain strange

  3. skepticism about celestial navigation as an elucidation

  4. showing interest in various ways accounted for the navigation sense of various trans migratory birds

  5. astonishment that animals apparently navigate in much the same way that human beings do
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

(3) (This is an 'inference' question, for which the key phrase and its location are given in question itself.) The full sentence in which the quoted phrase occurs is, ''Some scientists thought migrants determine their geographic position on earth by celestial navigation, almost as human navigators use stars and planets, but this would demand of the animals a fantastic map sense.'' This implies that the author thinks that birds are not capable of having such map sense. In other words, he is skeptic about the theory that birds determine their migratory routes using the position of the sun and the stars. So, (3) is the answer.

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