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.