問題詳情

C.The origins of nest-building remain obscure, but current observation of nest-building activities provide evidence of theirevolution. Clues to this evolutionary process can be found in the activities of play and in the behavior and movements of birdsduring mating, such as incessant pulling at strips of vegetation or scraping of the soil. During the early days of the reproductivecycle, the birds seem only to play with the building materials. In preparation for mating, they engage in activities that resemblenest-building, and continue these activities throughout and even after the mating cycle. Effective attempts at construction occuronly after mating.   Although nest-building is an instinctive ability, there is considerable adaptability in both site selection and use of materials,especially with those species which build quite elaborate constructions. Furthermore, some element of learning is often evidentsince younger birds do not build as well as their practiced elders. Young ravens, for example, first attempt to build with sticksof quite unsuitable size, while a jackdaw's first nest includes virtually any movable object. The novelist John Steinbeckrecorded the contents of a young osprey nest built in his garden, which included three shirts, a bath towel, and one arrow.   Birds also display remarkable behavior in collecting building materials. Crows have been seen to tear off stout greentwigs, and sparrow-hawks will dive purposefully onto a branch until it snaps and then hang upside down to break it off. Goldeneagles, over generations of work, construct enormous nests. One of these, examined after it had been dislodged by high winds,weighed almost two tons and included foundation branches almost two meters long. The carrying capacity of the eagles,however, is only relative to their size and most birds are able to carry an extra load of just over twenty percent of their bodyweight.
42. According to the passage, which of the following activities is characteristic of the early part of the reproductive cycle of birds?
(A) Selecting a mate
(B) Collecting nest-building materials
(C) Playing with nest-building materials
(D) Building a nest

參考答案

答案：C
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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