【推荐1】It’s late evening in the middle of the winter. The snow is deep, but off I go into the wild. Suddenly, I hear it: the howl (嚎叫) of wolves. Excitedly, I walk faster in the direction of the howling.

I’ve been working as a volunteer wolf tracker in Yellowstone National Park for over a year. It’s my job to follow wolves to record information about them. Like wolves, however, I don’t work alone. I’m one of a team of people who have been in a project to help reintroduce wolves to the park.

Humans have always feared wolves. From fairy tales to movies, the wolf is always the bad guy —a danger to humans and other animals. In the 1920s, the organizers of the park shared this view about wolves and made the decision to drive them away from the park. As a result, the number of elk (麋鹿) in the park increased. The elk started looking for food near river banks since they didn’t have to worry about wolves. This, in turn, stopped trees from growing along the rivers, doing great harm to the environment there.

The return of wolves has already made a big difference. To begin with, the elk soon learned to stay away from the rivers, so new trees have been able to grow there. The trees become home to new wildlife, such as birds, and provide food for more animals.

The park is now becoming more and more popular with those who want to see wolves in their natural environment. It has also helped the local people make more money. Tourists visit the area, stay in the local hotels, and eat in the local restaurants.

Looking at the wild animals and the beautiful sceneries around me, I am amazed at the changes the wolf has made to Yellowstone. And happily, it is playing a good guy in this story.

【推荐1】Chen Guanghui is a guardian for black-necked cranes(黑颈鹤) in the Dashanbao Black-necked Crane National Nature Reserve of Zhaotong city, in southwest China’s YunnanProvince. Whistling(吹口哨) is the secret language Chen uses to communicate with the black-necked cranes, a type of migratory bird under first class protection in China. She says different whistles signal different things. When she whistles in an increasing tone, she tries to tell the cranes: ask your companions to come back for lunch, and they would chirp(吱喳叫)to spread the message right away.

Living near the Dashanbao Nature Reserve, a major winter habitat(栖息地) for the rare species, Chen started to take care of them in 2003, a mission she took over from her mother, whose devotion dates back to the 1990s.

“In the first few days, I remembered they ran away as soon as I approached them. I was very upset and asked my mom to come back, and I was worried they would starve,”   says Chen. “I initially tried everything, even singing folk songs to attract them, but failed. Later, I used special whistles and gradually formed close bond with the cranes. ”

“I treat them as if they were my own children, and I’m always concerned about them, especially during snowy days when they can’t get food. I feel uncomfortable and anxious when I hear them chirp and usually rush to prepare corn for them. ” It’s never been an easy job, and Chen has sustained quite a few injuries over the years, even falling into frozen marsh(沼泽)while trying to save a trapped crane in 2008. However, she never gave up. With love and responsibility, she has persisted in caring for the cranes for about 20 years.

Thanks to the joint protection efforts of Chen and staff members at the nature reserve, now more than 1,900 black-necked cranes overwinter in the area each season every year, up from about 300 when the nature reserve was established.

【推荐2】The white rhinoceros (犀牛) is near-threatened due to massive illegal hunting; the mountain gorilla (大猩猩) is classed as endangered due to great habitat destruction. If no action is taken, these amazing creatures will undoubtedly be extinct before the end of the century. But scientists are working hard to stop this with some pretty cool drone tech (无人机技术).

One of the biggest dangers to endangered animals in the modern day comes from illegal hunting, which claims the lives of hundreds of white rhinos every year. While regular patrols (巡逻队) can drive hunters away from certain areas, hunters are often well-armed and unafraid to fire upon those hoping to protect the rhinos. This is where drones come in. If researchers work in these areas, there would be a real danger of coming into contact with the hunters. By having drones collect data, movement patterns and numbers of animals, researchers can get away from such dangers.

Drones can also be sent into the skies above difficult-to-reach areas to get data that would otherwise be tough to collect. For example, mountain gorillas are usually found in deep jungle, and organising an exploration can be expensive and demanding. Researchers can send drones over the forest to gather data about the habitat of the animals, and even take high quality images. This information can be priceless when it comes to an on-foot exploration, as researchers can get up-to-date information. In this situation, human-led surveys will still offer better results, but drones can play a huge part.

The downside presently is the cost, which can run into tens, if not thousands, of dollars. However, drone tech is still becoming a more favorable choice in the fight against wildlife extinction.

【推荐3】When Joseph Cook first landed on the Greenland ice sheet in 2010, he was expecting to see a primitive white environment. What he found was "colorful mix"-from blacks and grays to greens, purples and browns, with blue streams cutting through the ice. the rainbow colors Cook encountered are created by a collection of tiny life forms that reproduce on the surface of the ice sheet. Biodiversity is usually considered a good thing, but in this case the abundance of tiny life is speeding up ice melt, and likely causing global sea levels to rise faster than scientists have predicted

Cook says the tiny life forms he studies are contributing to the problem. One of these organisms is an algae(海藻) that grows in the thin layer of water on the surface of the ice. it produces purple-brown- pigment(色素) which acts “like a natural sunscreen, "says Cook, protecting the algae from the full force of the Arctic sunlight. The pigment also causes the ice to heat up and melt.

“If you go out on a hot day wearing a black T-shirt, you get warmer than if you go out on a hot day wearing a white T-shirt. The same thing happens on the ice," says Cook. "These algae, like the black T-shirt for the glacier, are causing it to warm up in the sun and melt faster.”

Cook’s research on a part of the Greenland ice sheet covering 3, 900 square miles revealed that algae is responsible for up to 13% of the ice melt. In some localized areas, the algae boosted melting by up to 26%.

Glacier algae are not a new phenomenon-there are records of them in the diaries of polar explorers from the 1870s, says Cook. What's becoming clear is that ice sheets are surprisingly dynamic and complex environments. "There are so many questions to answer, "says Cook. "It's kind of like a theme park for a scientist because there's just so much to do.