2020甘青宁三省联考高三4月联考答案及试题（高三4月金太阳全科）。Poole says before the country's
15yearlong conflict, the park was home to over 4,000 elephants.
However, by the time the conflict ended in 1992, about 90 percent
of them had been killed for ivory to get money. Of the less than
200 survivors, over 50 percent of adult females had no tusks.
Therefore, it is not surprising that the park's tuskless elephant
population has grown greatly.
This is not the first time researchers have observed a great
change in the population of elephants. At
Zambia's South Luangwa National Park and Lupande Game Management
Area, areas which were heavily hunted in the 1970s and 1980s, 35%
of elephants 25 years old or older and 13%of those younger than 25
are now without tusks. A 2008 study published in the
African Journal of Ecology found
that the number of tuskless females at the Ruaha National Park in
Tanzania went from 10.5 percent in 1969 to almost 40 percent in
1989, largely due to illegal hunting for ivory.
The
recent ban on ivory in both the US and China should
help get rid of, or at least reduce, elephant
hunting. However, scientists are not sure how long it will take for
elephants with a higher rate of tuskless females, to change
the_trend.
体裁：说明文 题材：人与自然 主题：没有长牙的大象
加载中，请稍候......
(2020-04-18 16:15:58) 
加载中…