2022-2023年英语周报七年级第50期答案汇总
作者：互联网
进入查看： 2022-2023年英语周报七年级第50期答案汇总
Non-target species, however, are often those that have their fortunes most greatly reshaped by the appearance of poles and wire. Australian fences intended to keep out dingoes are also barriers to long-necked turtles, which travel great distances over land when moving between nesting sites. In Botswana fences built to spare cattle from wildlife-borne disease result in serious interference with wildebeest (角马）migrations.
Not every creature fares badly. Hawks (鹰）in Montana gladly sit on newly built livestock fences to hunt small animals, while fence-based spiders in South Africa outperform their tree-based cousins when it comes to catching insects.
Often, though, the winners are creatures that cause trouble for existing ecosystems. Keeping dingoes out of large parts of Australia has allowed aggressive red foxes to multiply. Native rodents (啮齿类动物）have suffered as a result. Some have been brought to the edge of extinction.
What can we learn about the studies on fences?
Data on the impact of fences have been proved.
50% of the studies focus on just five countries.
Previous researches were complete and systematic.
About two-thirds of the studies focus on the target animals.
标签：based,target,fences,50,focus,七年级,2022,studies 来源： https://www.cnblogs.com/gaokaos/p/15924393.html