How many hippos are kept in Queen Elizabeth National Park now? [originaltext]

(16-1)For viewing hippos Queen Elizabeth National Park in Uganda is probably one of the best places in Africa. Surrounded by mountains, the lakes and the channel that connects them provide a perfect home for thousands of hippos.
    However, years ago when the Europeans came, they made the area a game-reserve place and later a national park.(14/16 --2)The protection of hippos, people found, resulted in an event that hippos increased, eventually in an area that could support no more than 4,000 hippos and where 14,000 lived. It brought about a chain of bad reactions.
    The first problem was a shortage of food. A normal hippo needed 400 pounds of fresh grass every night. Soon, the grassland along the shore of the lakes was destroyed. With the growth of the ground eroded by hippos, thorn scrub spread everywhere. Hippos left much dung in the waters which made the lakes overfull of fish. Fish attracted a lot of storks, which destroyed the very rare species of trees. Hippos’ dung also fed so many aquatic insects which attracted more birds.(15)In such a small area with so many animals, insects and birds, the balance of nature had been upset.(16-3)The good intention in protecting the hippos may bring an undesirable damage to the area.