A California wind farm will become the first in the U. S. to avoid charges if a limited number of eagles are injured or die when they run into the huge turning blades(桨叶), the U. S. Fish and Wildlife Service said Thursday.

The Shiloh IV Wind Project LLC, 60 miles east of San Francisco, will receive a special permit allowing up to five golden eagles to be accidentally killed over five years. Previously, such eagle deaths could potentially draw criminal charges and discourage private investment in wind farms.

Agency Director Daniel Ashe said the permit encourages development of renewable energy while requiring the wind company to take steps to protect eagles from turbines(涡轮机)and power lines. The move will help California reach its goal of producing one-third of its energy from renewable sources by 2020, he said.

Michael Hutchins of the American Bird Conservancy said he believes the five-year permit for the California wind farm is reasonable, but he said the rapid expansion of wind energy has gotten ahead of the science and regulation to protect all types of birds. Too often, he said, wind farms are built in migratory patterns or near wetlands.

Birds on the hunt can become dizzy by what’s on the ground and fly into the blades, Hutchins said.

“Is it really green energy if it’s going to kill hundreds of thousands of birds or bats each year?” he said. “The whole system needs a much harder look.”

Shiloh IV Wind Project is a 102-megawatt wind farm operating since 2012 and made up of 50 turbines in Solano County.

Shiloh is the first to obtain a permit. Marie Strassburger, the U. S. Fish and Wildlife Service’s regional migratory bird chief, said that obtaining one requires a lengthy process, and because this is the first of its kind, officials have carefully made conversation plans with the wind company.

“It’s not a quick, efficient process by any means,” Strassburger said.

Federal wildlife officials in California, Nevada and Southern Oregon are working on two more applications for five-year eagle permits and one for 30 years, said Scott Flaherty of the U. S. Fish and Wildlife Service in Sacramento. Eagles are not listed as endangered, but they are protected under a federal act.

Due to climate changes, Arctic ice is breaking up earlier in the spring, and its area is decreasing. This is creating problems for polar bears that make their homes off northern Alaska and in Hudson Bay.

Polar bears off Alaska normally hunt and raise their young on ice sheets that float on the ocean. But as the ice has melted, the polar bears have been forced to spend more time on land. There, they have begun to frequent beaches, feeding on the remains of whales caught by native hunters. For polar bears, this food is less nutritious than seals that they normally catch on ice sheets. The shrinking (减少) ice has also forced more polar bears into the ocean. In the past, they only had to swim short distances between ice sheets. But as the ice has shrunk, polar bears have been forced to swim longer and longer distances in the open ocean. This poses a severe danger during rough weather, and an increasing number of drowned polar bears have been observed.

In Hudson Bay, the ice breaks up three weeks earlier in the spring now than it did 20 years ago. Polar bears on Hudson Bay fast (绝食) during the summer, waiting for ice to form in the fall to hunt. Every year, the summer gets longer, and the bears get skinnier. Over the past 25 years, the average weight of the female bears has dropped 68 kg. This loss affects their ability to reproduce, and already the number of births has dropped by 15 percent. Unless the bears can learn to survive these climate changes, these giants of the ice may one day disappear.

Students at St. Stanislaus High School in Mississippi are among the volunteers along US coasts raising oysters (牡蛎) to help restore, or repair weakened reefs (礁). Oyster reefs are an important part of coastal environments. Each oyster cleans 95 to 190 liters of water a day. The reefs provide living space for shrimp, crabs and fish. They also protect coastlines. In the states of Maryland, Virginia, Mississippi, and Alabama, now there are more than 1,000 oyster gardens. Most of them are in wire cages hanging from private ports.

Colin Wood, one student looking after the St. Stanislaus garden, said he was excited by the hands-on work. “I didn’t realize oysters had a big influence on the environment. And 50,000 to 55,000 adult oysters grown here each year go to reefs in Mobile Bay,” he said.

In the 1950s, an average of 37,400 tons of oysters were taken yearly from partly salty waters in the US. But US oyster harvests fell sharply in the 1990s. Data showed the cause of the drop could be overharvesting, pollution, pests and other problems. Then oyster gardening started.

Oyster gardening uses many of the same methods as farming. Farmers around the country grow oysters near the surface of water. Oysters develop much faster where the water holds more food they eat and enemies can be more easily removed. But the oysters are not being grown to be eaten. Oyster gardens get pulled from the water every seven to ten days. The time out of the water is used to clear out small animals, keep oysters from growing through the wires, and dry and clean off plant-life growing on the wires.

Bob Stokes, the director of the Galveston Bay Foundation in Texas, says, “Oyster gardening is as much about education as it is restoration.”