【推荐1】Who would win in a fight, a lion or a tiger? Well, if size has anything to do with the matter, the tiger would win. That’s because tigers are the largest of all cat species. Tigers are not only large, they are also fast. They can sprint as fast as 40 miles per hour for short distances and leap as far as 30 feet horizontally. You might not think that such large, fast, and fierce creatures need help to survive, but they do.

It is estimated that at the start of the 20th century, there were over 100,000 tigers living in the wild. By the turn of the century, the number of tigers outside of captivity dwindled to just over 3,000. Interestingly, the most serious threats that tigers face come from a much smaller species, one with an average weight of around 140 lbs. That species is Homo sapiens, better known as humans. Humans threaten tigers in primarily two ways: hunting and destroying habitat.

Tigers are hunted for many reasons. People have long valued the famous striped skins. Though trading tiger skins is now illegal in most parts of the world, tiger pelts are worth around $10,000 on the black market. Though the fur would be incentive enough for most poachers, other parts of the tiger can also fetch a pretty penny. Some people in China and other Asian cultures believe that various tiger parts have healing properties. Traditional Chinese medicine calls for the use of tiger bones, amongst other parts, in some prescriptions.

Tigers have also been hunted as game. In other words, people hunted tigers solely for the thrill and achievement of killing them. Such killings took place in large scale during the 19th and early 20th centuries, when an English hunter might claim to kill over a hundred tigers in their hunting career. Though this practice is much less popular today than it was in the past, it has not ceased entirely.

Humans have done considerable damage to the world’s tiger population through hunting, but perhaps more damage has been caused through the destruction of habitat. Tigers once ranged widely across Asia, all the way from Turkey to the eastern coast of Russia. But over the past 100 years, tigers have lost 93% of their historic range. Instead of spanning all the way across Asia, the tiger population is now isolated in small pockets in southern and southeastern Asia. This is because humans have drastically changed the environments. Humans have built towns and cities. Road and transit systems were created to connect these towns and cities. To feed the people living in these areas, forests and fields have been cleared to create farmland.

A major obstacle to preserving tigers is the enormous amount of territory that each tiger requires. Each wild tiger demands between 200 and 300 square miles. Tigers are also both territorial and solitary animals. This means that they are protective of the areas that they claim and they generally do not share with other tigers. Because tigers need so much territory, it is really difficult for conservationists to acquire enough land to support a large population of tigers.

【推荐3】The mass death of flying foxes in extreme heat in North Queensland last month underlines the importance of University of Queensland wildlife research released today.The UQ research sheds light on how various species have responded to major climate events.

A study led by UQ School of Earth and Environmental Science researcher Dr Sean Maxwell has spent more than 70 years quantifying the responses of various species.

“The growing frequency and intensity of extreme weather events such as cyclones, droughts and floods is causing unpredictable and immediate changes to ecosystems and blocking existing management efforts,” Dr Maxwell said.“Some of the negative responses we found were quite concerning, including more than 100 cases of dramatic population declines and 31 cases of local population extinction following an extreme event.”

"Populations of critically endangered bird species in Hawaii, such as the palia, have been annihilated due to drought, leaving none of its kind, and populations of lizard species have been wiped out due to cyclones in the Bahamas."

Cyclones were the most common extreme event for birds, fish, plants and reptiles, while mammals and amphibians were most responsive to drought events, with drought leading to 12 cases of major population decline in mammals.Drought also led to 13 cases of breeding declines in bird populations and 12 cases of changes in the composition of invertebrate communities.

UQ Centre for Biodiversity and Conservation Science director Professor James Watson said the detailed information would help inform ecosystem management.

“The research clearly shows species will respond, often negatively, to extreme events,” Professor Watson said.“As climate change continues to ensure extreme climate and weather events are more and more common,we now need to act to ensure species have the best chance to survive.Wherever possible, high quality and intact habitat areas should be retained, as these are the places where species are most resilient(易恢复的) to increasing exposure to extreme events.”

【推荐2】Lake Baikal(贝加尔湖)is the biggest body of fresh water on Earth. It’s about 1.6km in depth and is also the deepest. Several unusual animals call it home, including the world’s only species of freshwater seal. There are a large number of Baikal seals, about 8, 000-10, 000. But the lake is nutrient-poor, so how they do so well has been a puzzle. A study conducted by Yuuki Watanabe of the National Institute of Polar Research, in Tokyo, suggests a possible answer.

Most seals eat fish. And Baikal seals do have needle-like teeth. But in 1982 researchers noted that they had some specialized comb-like teeth behind the needle-like ones. At the time, nobody knew what they were for. But Dr. Watanabe supposed that they might be an adaptation for feeding on other tiny creatures living in the lake.

Seals arrived in Baikal two million years ago, from the Arctic Ocean. So did some much smaller sea creatures, known as amphipods(片脚类动物). They have diversified into more than 340 native species. Sea creatures the size of seals would normally see amphipods to be too small to hunt. But Dr. Watanabe wondered if Baikal seals’ comb-like teeth might have evolved to enable the seals to hunt these tiny creatures to make them useful prey-just as some whales collect extremely small shellfish using comb-like structures. He and his colleagues therefore attached waterproof video cameras to a few seals to monitor what they were getting up to.

Scenes from the cameras showed that the seals were indeed pursuing the groups of amphipods at night. Dr. Watanabe estimated that each seal caught an average of 57 amphipods per dive and thus thousands of them a day. The needle-like teeth are not useless, for the seals do hunt fish as well. They compete with those fish for the amphipods, thus perhaps maintaining themselves in larger numbers.