Migratory (迁徙的) birds are declining globally because of the way that humans have changed the landscape over recent decades — according to new research from the University of East Anglia (UEA).

A new study published today reveals that population declines have been greatest among species that migrate to areas with more human infrastructure — roads, buildings, power lines, wind turbines (涡轮机) — as well as more population and hunting levels.

Dr. James Gilroy, from UEA’s School of Environmental Sciences, said, “We know that migratory birds are in greater decline than non-migratory species, but it’s not clear why. We want to find out where in their life cycles these migratory species are most exposed to human impacts.”

The research team identified 16 human-induced threats to migratory birds, including infrastructure associated with bird disturbance and impacts, transformation of land from natural habitat to human land use, and climate change. Advances in satellite imagery allowed the team to map each of the 16 threats across Europe, Africa and Western Asia. The team also created the first ever large-scale map of hunting pressure across the region. A total of 103 species of migrating birds were studied, including many rapidly declining species like the turtle dove and the common cuckoo, using large-scale datasets. The team calculated threat scores for factors such as habitat loss and climate change, across breeding locations, as well as non-breeding ranges. They then explored the relationships between these threat scores and bird population trends calculated from 1985 to 2018 by the Pan-European Common Bird Monitoring Scheme (PECBMS).

Dr. Aldina Franco, also from UEA’s School of Environmental Sciences, said, “Our findings are important because we need to understand where declining species are being most impacted by humans across their seasonal migrations. Locating where birds are most exposed to these threats could help us target conservation actions.”

After the heavy rain passes, a man at a company that lies on the riverbank arrives for work. At the water’s edge, he notices a baby beaver (海狸) balls up on the ground.Realizing that the animal needs help, the man picks him up and drives to a nearby animal hospital.From here the beaver is sent to the Calgary Wildlife Rehabilitation Society (CWRS), where he will begin his recovery.

Vets check the beaver — now named Birch — for wounds or broken bones. Luckily they find no injuries.“But he’s a real little animal — only three and a half pounds,” says Andrea Hunt, a worker at the rehab center.According to his weight, they think that Birch is about eight weeks old.“Baby beavers stay with their families for one to two years,” Hunt says.“He’s not ready to care for himself.If he hadn’t been saved, he almost certainly wouldn’t have survived.”

To keep Birch from getting lonely, Hunt pairs him with another baby beaver named Aspen. At first they’re fed a milky cereal. A few weeks later, Birch and Aspen begin a diet of solid food that includes leafy kale and collard greens. Wood is also on the menu.For exercise, each beaver receives its own pool to swim in.

About a year later, Birch weighs 27 pounds. “Not only is he healthy, but he’s also learned good survival skills,” Hunt says. “It’s time to let him go.” Early one morning the beaver is driven into a Canadian forest to be set free.Birch is carried in a cage (笼子) to the bank of a lake. When the door opens, he carefully steps out, then jumps into the water and swims away. “We’ll miss Birch,” Hunt says.“But nothing feels better than putting an animal back where it should be.”

Every summer, the Serengeti plains of Africa are worth visiting. Millions of wild animals begin their 1,800-mile journey northwards on their annual migratory (迁移的) route.

In the month of November, polar bears in their thousands cross the Canadian Arctic, as they head towards the ice sheets of Hudson Bay. The sea ice that forms every winter is the key to the bear’s managing to exist, for here they hunt for seals (海豹).

The Great Bustard, one of the heaviest flying birds, migrates each year across Europe and Asia to its wintering grounds. Unluckily, these and other migratory animals are in danger from human activity.

We have written several articles on climate change and the effect of rising ocean temperatures. Since 1979, ice sheets in the Arctic have gone down by 30 percent. What does this mean for polar bears? They are forced to stay on land for longer periods of time, which delays their search for food. As a result, bears today are 60 pounds lighter than what they were. Besides, smaller bears also produce weaker babies, and their chances of survival are at risk. In the plains of Africa, migratory animals like gazelles are traveling long distances for food, just to avoid falling prey (猎物) to humans who hunt them.

In an unusual step, experts from 120 countries have agreed to protect 31 migratory mammals, fish and birds. The United Nation’s 11th annual Conservation of Migratory Species of Wild Animals was held in Quito, Ecuador. For the first time, 900 experts attended the conference, and the enthusiastic support shows the world is united in conservation (保护) efforts.

What does getting on a protected list mean? Countries that have signed the agreement will be required to pass laws locally and work with other countries that fall within the animal’s migratory path. Only one animal did not make the list. The African lion was rejected (拒绝) for lack of information of the countries where it lives.