Grassland songbirds often nest in the same grassland-wetland complexes as waterfowl, particularly in a certain part of those complexes, namely, upland habitats surrounding wetlands. Although some wildlife management procedures directed at waterfowl, such as habitat enhancement or restoration, may also benefit songbirds , the impact of others, especially the control of waterfowl predators, remains difficult to predict. For example, most predators of waterfowl nests prey opportunistically on songbird nests, and removing these predators could directly increase songbird nesting success. Alternatively, small mammals such as mice and ground squirrels are important in the diet of many waterfowl-nest predators and can themselves be important predators of songbird nets. Thus. Removing waterfowl-nest predators could affect songbird nesting success through subsequent increases in small-mammal populations.
In 1995 and 1996, researchers trapped and removed certain waterfowlnest predators. primary raccoons and striped skunks, then observed subsequent survival rates for songbird nests. Surprisingly. They observed no significant effect on songbird nesting success. This may be due to several factors. Neither raccoons nor striped skunks consume ground squirrels, which are important predators of songbird nests. Thus, their removal may not have led to significant increases in populations of smaller predators. Additionally, both raccoons and striped skunks prefer wetlands and spend little time in upland habitats; removing these species may not have increased the nesting success of songbirds in the uplands enough to allow detection.
The passage suggests that removing Waterfowl-nest predators could possibly Have a negative effect on songbird populations because
songbird populations could then grow to unsustainable numbers
small-mammal population could then move out of the uplands into wetland areas
competition among remaining waterfowl-nest predators could decrease significantly
a resulting increase in waterfowl populations could crowd out songbird populations
a resulting increase in small-mammal populations could increase small-mammal predation on songbirds
此讲解的内容由AI生成,还未经人工审阅,仅供参考。
正确答案是 E。解释:文章指出,从水鸟窝的捕食者中清除某些物种,可能会通过增加小型哺乳动物的数量而影响歌鸟窝成功率。1995年和1996年,研究人员捕捉和清除了某些水鸟窝捕食者,然后观察了歌鸟窝的随后生存率,令人惊讶的是,他们没有观察到significant effect(显著影响),这可能是因为清除这些物种并没有导致小型捕食者(小型哺乳动物)数量的显著增加。因此,如果清除水鸟窝捕食者,会导致小型哺乳动物数量的增加,从而增加小型哺乳动物对歌鸟窝的捕食,所以E选项是正确的。