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OFFICIAL37 According to paragraph 5, why did conservationists decide to translocate the Seychelles warbler from Cousin Island to two other islands?

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Direct Species Translocation
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It is becoming increasingly common for conservationists to move individual animals or entire species from one site to another. This may be either to establish a new population where a population of conspecifics (animals or plants belonging to the same species) has become extinct or to add individuals to an existing population. The former is termed reintroduction and the latter reinforcement. In both cases, wild individuals are captured in one location and translocated directly to another.

Direct translocation has been used a wide range of plants and animals and was carried out to maintain populations as a source of food long before conservation was a familiar term. The number of translocations carried out under the banner of conservation has increased rapidly, and this has led to criticism of the technique because of the lack of evaluation of its efficacy and because of its potential disadvantages. The nature of translocation ranges from highly organized and researched national or international programs to ad hoc releases of rescued animals by well- intentioned animal lovers. In a fragmented landscape where many populations and habitats are isolated from others, translocations can play an effective role in conservation strategies; they can increase the number of existing populations or increase the size, genetic diversity, and demographic balance of a small population, consequently increasing its chances of survival.

Translocation clearly has a role in the recovery of species that have substantially declined and is the most likely method by which many sedentary species can recover all or part of their former range. However, against this is the potential for reinforcement translocations to spread disease from one population to another or to introduce deleterious or maladaptive genes to a population. Additionally, translocation of predators or competitors may have negative impacts on other species, resulting in an overall loss of diversity. Last but not least of these considerations is the effort and resources required in this type of action, which need to be justified by evidence of the likely benefits.

Despite the large number of tranlocations that have taken place, there is surprisingly little evidence of the efficacy of such actions. This is partly because many translocations have not been strictly for conservation; neither have they been official nor legal, let alone scientific in their approach. Successful translocations inevitably get recorded and gain attention, whereas failures may never be recorded at all. This makes appraisal of the method very difficult. One key problem is a definition of success. Is translocation successful if the individuals survive the first week or a year, or do they need to reproduce for one or several generations? Whatever the answer, it is clear that a general framework is required to ensure that any translocation is justified, has a realistic chance of success, and will be properly monitored and evaluated for the benefit of future efforts.

An example of apparent translocation success involves the threatened Seychelles warbler. This species was once confined to Cousin Island, one of the Seychelles islands, and reduced to 26 individuals. Careful habitat management increased this number to over 300 birds, but the single population remained vulnerable to local catastrophic events. The decision was taken to translocate individuals to two nearby islands to reduce this risk. The translocations took place in 1988 and 1990, and both have resulted in healthy breeding populations. A successful translocation exercise also appears to have been achieved with red howler monkeys in French Guiana. A howler population was translocated from a site due to be flooded for hydroelectric power generation. The release site was an area where local hunting had reduced the density of the resident howler population. Released troops of monkeys were kept under visual observation and followed by radio tracking of 16 females. Although the troops appeared to undergo initial problems, causing them to split up, all the tracked females settled into normal behavioral patterns.

Unfortunately, the success stories are at least matched by accounts of failure. Reviewing translocation of amphibians and reptiles, researchers C.Kenneth Dodd and Richard A. Siegel concluded that most projects have not demonstrated success as conservation techniques and should not be advocated as though they were acceptable management and mitigation practices.

9.According to paragraph 5, why did conservationists decide to translocate the Seychelles warbler from Cousin Island to two other islands?

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正确答案:C
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【题目翻译】根据第5段,为什么环保主义者决定把塞舌尔莺从表亲岛转移到另外两个岛上? A:他们没有成功地增加堂兄岛上的莺的数量。 B:这三个岛都是土生土长的。 C:他们想确保莺类在表亲岛的灾难中幸存下来。 D:他们认为表亲岛上的人类活动会威胁到莺。 【判定题型】:题目问的是文章中的具体细节信息,故根据题目问法可以判断本题为事实信息题。 【关键词定位】本题题干给的关键词是Seychelles warbler,Cousin Island和two other islands。根据这三个词定位到这一句:Careful habitat management increased this number to over 300 birds, but the single population remained vulnerable to local catastrophic events. The decision was taken to translocate individuals to two nearby islands to reduce this risk. 意思是“Seychelles warbler这个物种一开始濒危,经过人类的管理增加到了300多只,但是这个种群还是对于当地的灾难性事件没什么防御能力。所以人们决定把它们引入到另外两个相邻的岛屿上,以降低绝种的风险”。 【逻辑分析】说了Seychelles warbler这个物种的拯救过程。 【选项分析】 选项A说人们没有成功地增加这种鸟的数量,错误,是成功增加了; 选项B说这种鸟对于三个岛来说都是土生土长的,错误,后面那两个相邻的岛屿是后来才人为引入的鸟; 选项C说他们想保证这种鸟可以活过Cousin Island上的灾害,对的;选择C。 选项D说人类在Cousin Island上的行为会危害这种鸟,错误,是自然灾害会威胁它们的生存。

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