标签：Mammoths 相关文章
Colombian mammoths had to feed almost round the clock to fuel their bulky bodies. But as the ice age ended, food was not the mammoths' biggest problem. A new and deadly predator began to infiltrate the plains, a match for any prey, even the mighty ma
探索与发现2012年
To find the answers, we need to rewind history around 14,000 years to a time when the first people set foot in North America. The continent was about to undergo a profound change, a change these new arrivals may have played a part in. Throughout the
探索与发现2013年
...and may trace their ancestry all the way back to the first dogs to enter North America. The Carolina dogs are pack animals with a strick hierarchy topped by an alpha male. Like most wild dogs, they hunt in groups. But many of the kills they make a
探索与发现2013年
Just over 500 years ago, Europeans arrived in North America. And with these colonizers came an animal that hadnt been seen here for thousands of years. The horse returned to the Americas, now tamed and carrying the Spanish conquistadors. This new for
探索与发现2013年
By the mid 1800s, the horse and the cowboy had come to symbolize the wild west. And of course, with the cowboys came cattle. As the bison quickly vanished from the landscape, cattle filled their place. Meanwhile increasing numbers of the tame horses
探索与发现2013年
This may look like a safari through the African savanna. In fact it's a theme park in Florida. And it allows people to experience a world outside their own. In some ways, they are visiting a land from another time. 14 thousand years ago, large parts
探索与发现2013年
Its also a prime hunting ground for red-tailed hawks. And they have the perfect nesting site right next to it. Theyd moved in on the top floor of this expensive Manhattan apartment block. It acts like a surrogate tree, supporting their large nest. Th
探索与发现2013年
Where purple martins had once laid their eggs in hollow threes, in time, they came to rely almost totally on people to provide nests for them. These artificial nests were made from dried out squashes known as gourds. The shape made them perfect nesti
探索与发现2013年
At first, the Europeans relied heavily on local food supply by native people. But as they settled in, their farming practices began to shape the landscape of North America. The plow allowed them to farm larger areas of land, helping to feed the expan
探索与发现2013年
And farming fuelled the growth of another habitat, one that would become an even bigger challenge to North America's wildlife. The modern city was born. The city is an artificial environment, built around the needs of millions of people, and yet it a
探索与发现2013年
The owls can raise anything from 1 to 12 chicks in a summer season. To survive, their young will have to quickly learn to negotiate the dangers of city life. Longer hunting trips are sometimes necessary as open land disappears. But so long as the cit
探索与发现2013年
Although many of these city foxes do get killed by cars, the population as a whole is thriving. Thats because a regular supply of water means a regular supply of prey, including voles and ground squirrels. Playing on the streets at night is dangerous
探索与发现2013年
Moose mainly browse on trees and shrubs, but they will also sample something new. They have a soft spot for pumpkins left out after Halloween. As many as 1,000 moose may enter Anchorage in winter, snowfall here is lower than its surrounding hills and
探索与发现2013年
This disused car park is a near-perfect location for raising chicks, and only a short flight from a plentiful supply of food. Skimmers get their name from their unusual feeding technique--their extended lower bill detects fish just below the water su
探索与发现2013年
But there is at least one place in Florida where the manatees benefit from humans being around. Clean, hot water released from this power plant turns a man-made inlet into a hot tub. And during winter months when sea temperatures drop below 20 degree
探索与发现2013年
This mass roosting takes place soon after the summer nesting season. Its a chance for the birds to molt before they fly south for the winter. As Vauxs swift numbers reach a peak in mid September, they attract attention from the locals. Coopers hawks
探索与发现2013年