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Crows Crows are probably the most frequently met and easily identifiable members of the native fauna of the United States. The great number of tales, legends, and myths about these birds indicates that people have been exceptionally interested in them for a long time. On the other hand, when it comes to substantive─particularly behavioral─information, crows are less well known than many comparably common species and, for that matter, not a few quite uncommon ones, the endangered California condor, to cite one obvious example .There are practical reasons for this. Crows are notoriously poor and aggravating subjects for field research. Keen observers and quick learners, they are astute about the intentions of other creatures, including researchers, and adept at avoiding them. Because they are so numerous, active, and monochromatic, it is difficult to distinguish one crow from another. Bands, radio transmitters, or other identifying devices can be attached to them, but this of course requires catching live crows, who are among the wariest and most untrappable of birds. Technical difficulties aside, crow research is daunting because the ways of these birds are so complex and various. As preeminent generalists, members of this species ingeniously exploit a great range of habitats and resources, and they can quickly adjust to changes in their circumstances. Being so educable, individual birds have markedly different interests and inclinations, strategies and scams. For example, one pet crow learned how to let a dog out of its kennel by pulling the pin on the door. When the dog escaped, the bird went into the kennel and ate its food. Key 烏鴉 烏鴉可能是美國本土動物中最常見、也是最容易識別的成員(物種)。關于它的奇聞異事和神話傳說(故事、傳說和神話)流傳眾多，可見，人們對它的濃厚興趣由來已久。另一方面，在提及對它的本性——特別是行為方面的了解時，與其他同樣普通和一些非常罕見的物種——一個顯而易見的例子是加州瀕臨滅絕的禿鷲——相比，它更鮮為人知。這其中有一些實際的原因。 眾所周知，野外的烏鴉研究成果甚少，并讓研究者苦惱不已。它們觀察敏銳，領悟快捷，善于分辨其他動物和研究人員的意圖，并能巧妙地避開他們。由于烏鴉數(shù)量眾多、顏色單一、機警靈活，人們很難把它們區(qū)分開來。人們當然可以把腳環(huán)、無線電發(fā)射機和其他識別裝置縛在烏鴉身上，但這卻要滿足一個前提，那就是活抓烏鴉——但這卻是最為機警、最難抓到的鳥類之一。 烏鴉的研究之所以令人卻步，撇開技術上的困難不談，其原因之一便是它們生活方式復雜多變。它們是超凡的多面手，其種族中的一些成員創(chuàng)造性地開發(fā)了大量的棲息地、利用大量的資源，而且能很快適應環(huán)境的變化。由于善于學習，每個烏鴉個體都有迥然不同的興趣、愛好，策略和花招。比如，有一只寵物烏鴉，學會將狗窩上的門閂拉開放狗出窩。狗出窩后，它便進去，享用了狗的美食。 編輯推薦：2016年下半年考試時間11月5日-6日 2016年11月翻譯資格考試報名時間及入口 |
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