1
00:00:00,000 --> 00:00:04,000
Return of the Wilderness, Yellowstone National Park.

2
00:00:05,000 --> 00:00:09,000
The mammoth geysers with their bursts of steam and boiling water.

3
00:00:10,000 --> 00:00:18,000
The jet can rise as high as 50 metres, erupting 45 tonnes of water around every hour.

4
00:00:19,000 --> 00:00:25,000
The park is home to some 60 species of wildlife, with over 40,000 animals.

5
00:00:30,000 --> 00:00:36,000
It's one of the few places left in North America where the natural environment remains intact.

6
00:00:40,000 --> 00:00:50,000
Concerned about the rapid loss of wildlife, the explorer John Muir pleaded for the protection of nature and appealed for the establishment of a national park.

7
00:00:51,000 --> 00:00:54,000
It became the first one in 1872.

8
00:00:55,000 --> 00:01:05,000
Wildlife was protected and efforts were made to preserve the bison once on the edge of extinction to recover to a population of about 3,000 in total.

9
00:01:08,000 --> 00:01:12,000
Yellowstone in the old days was a habitat for timber wolves.

10
00:01:14,000 --> 00:01:21,000
But in the 1930s, they were hunted to extinction to protect domestic animals.

11
00:01:22,000 --> 00:01:28,000
The elk population greatly increased in number in the absence of a natural enemy.

12
00:01:30,000 --> 00:01:33,000
The grassland could not support the herds.

13
00:01:34,000 --> 00:01:38,000
Coyotes had tripled their number and replaced the wolves.

14
00:01:39,000 --> 00:01:47,000
As a result, small animals that coyotes fed on decreased, threatening the existence of other animals feeding on small animals.

15
00:01:48,000 --> 00:01:53,000
31 grey wolves were introduced from Canada in 1995.

16
00:01:54,000 --> 00:01:58,000
Eight years later, they increased in number to over 200.

17
00:01:59,000 --> 00:02:04,000
The number of elks has since decreased and the plains are gradually regaining their original state.

18
00:02:05,000 --> 00:02:12,000
Hunted by the grey wolves, the number of coyotes decreased and the number of small animals returned to their original figures.

19
00:02:13,000 --> 00:02:17,000
Lightning causes forest fire almost every year in Yellowstone.

20
00:02:18,000 --> 00:02:22,000
Firefighting is, however, kept minimal, leaving nature to recover by itself.

21
00:02:23,000 --> 00:02:28,000
It has been found that the bushfires could actually help maintain the cycle of nature.

22
00:02:29,000 --> 00:02:34,000
Some pine cones pop out their seed when the temperature reaches 113 degrees Celsius.

23
00:02:35,000 --> 00:02:41,000
Burned forest ground will become a base for new sprouting trees and the forest will grow again.

24
00:02:42,000 --> 00:02:47,000
Bushfires play an important role in rejuvenating and maintaining the forest.

25
00:02:49,000 --> 00:02:54,000
Yellowstone teaches us how fragile and complex the balance of nature can be.