A new study has found that animals are changing to fit in the warmer world. The shape changes are an example of evolution (进化). They let animals fit in changing environments. As early as 1877, US scientist Joel Asaph Allen found a classic example of evolution in action, known as Allen’s Rule. This says that warm-blooded animals are more likely to have longer ears and tails (尾巴) if they live in warmer conditions, compared with similar animals in colder places.

The long body parts provide a bigger skin (皮肤) surface that they can use to prevent their body temperature from being too high.

A team led by Sana Ryding of Deakin University, in Australia, set out to test whether Allen’s Rule worked because the world has got warmer in the past 150 years. To do this, they looked at several studies into changing animal shapes to see if they are connected to the temperature.

Among the results, the team found that the bills (喙) of several Australian birds had grown by between 4% and 10% since 1871. They also found that wood mice are growing longer tails and bats (蝙蝠) in warmer environments are growing bigger wings. Ears are especially likely to get bigger because they are good at avoiding heat. “It just means they are changing to fit in the warmer world, but not all animals may be able to fit quickly enough,” says Ryding.

In the cold winter, a male eagle was flying above the snowfield for only one aim—the food. This strong eagle hunted for the food with his eyes, but what jumped into his view was just the endless snow.

The air temperature suddenly dropped, so the male eagle helplessly and hopelessly landed on the cliff. He had already flown for one whole day, yet hunting nothing...

Time changed back to the day before. After watching her husband fly away from the nest, the female eagle softly held her two baby eagles who were nearly frozen to death. She protected their young bodies under her big wings. She expected her husband to bring back the food. There was a dead rabbit nearby, which supported the family for ten days. They had eaten it up.

At the end of that short day, which seemed like a long life, the female eagle still couldn’t see her husband come back, feeling that one baby eagle became ice-cold.

The female eagle thought that she should do something. So she pulled apart her own chest with the sharp beak. She told her last baby “Eat me...” with the last strength.

Outside, the male eagle stood for a long time to look for the food. Suddenly, a leaden object jumped into his eyes. The male eagle nosed down to see it clearly. That was a gray rabbit. The male eagle jumped on the rabbit.

At that moment, the rabbit didn’t hide or escape, but crept tightly upon the snowfield. The male eagle caught the rabbit and killed it. When getting ready to fly away, he was shocked. Under the body of the old gray rabbit, there were four frozen baby rabbits lying there.

Love is broad and profound, yet it’s also cruel.

Margays (虎猫) are small wild cats about the size of house cats. They mainly live in tropical (热带的) forests from Mexico to northern Argentina and spend a lot of their lives in trees. They not only hunt in the treetops, but also eat and sleep there.

Margays are skillful climbers. Their feet are wide and soft, so they can hold on to tree branches. Their 17-inch-long tails provide excellent balance (平衡) as they move around in the treetops. The small cats are able to move quickly, so they can catch animals that other wild cats can’t. Margays usually eat birds, snakes and mice, and can even catch small monkeys. They also eat grass, fruit and other vegetation.

Not many people get a chance to watch these cats. Margays are secretive (隐秘的) animals, and it’s difficult to see them in the wild. Thanks to scientists, margays’ characteristics and habits aren’t a complete mystery. They weigh only around 10 pounds. They’re solitary (独居的) animals that are active mostly at night, and they have huge eyes that help them see in the dark. These cats don’t like to cross open, treeless areas. They stick to the tropical forests. Although margays spend a lot of time in trees, they can run fast on the ground too.

Margays aren’t in danger now. But the cats are considered vulnerable (易受伤害的). Tropical forests are necessary to margays, so clearing forests for farms is the biggest risk to them. We need to protect tropical forests to help margays.