【推荐1】Earth’s second-longest man-made structure, though, is not a wall, but a fence. It spreads about 5,614 km across eastern Australia and is intended to stop the country’s dingoes (野犬) from hunting sheep, which are farmed mainly to the south.

Australia’s dingo fence does not stand alone. There are millions of kilometres of fences in the world. Some are aimed to limit the movement of animals, some the movement of people, and some only to mark the boundary (界限).

Recently things have been changed by a report from Professor Alex Mclnturff. One discovery he has made is that more than half of the fence research studies focus on just five countries-America, Australia, Botswana, China and South Africa. A second is that only a third of those examined the impact of fences on target species involved, meaning the animals purposely intended to be kept in or out.

In fact, Australian fences intended to keep out dingoes are also barriers (障碍) to long-necked turtles, which travel great distances over land when moving between nesting sites. In Botswana fences built to prevent cattle from wildlife-borne disease influence the migration routes of wildebeest.

Fences are not so bad for every creature. Hawks in Montana gladly sit on newly built fences to hunt small animals, while fence-based spiders in South Africa achieve better results than their tree-based cousins when it comes to catching insects.

Often, though, the winners are creatures that cause trouble for ecological environment. Keeping dingoes out of large parts of Australia has allowed red foxes to increase greatly. Native rodents (啮齿类动物) have suffered as a result. Some have been brought to the edge of extinction.

【推荐3】Some birds are inside decorators, placing big, showy feathers in their nests. But rather than beautifying their homes, these birds may be trying to scare nest-stealing neighbors.

Birds sometimes weave feathers into their nests to provide insulation (隔绝). But behavioral ecologists Karen Wiebe and Tore Slagsvold also saw birds placing large feathers on the surfaces of nests. Those feathers wouldn’t help with warmth. The researchers wondered whether the birds might be using the decorations to send a message.

For birds that nest in holes, competition for nests can be really fierce. Birds scream and fight, sometimes killing an opponent. But these holes can also hide danger. Eagles or other predators may be hiding inside. If a nest contains feathers or other remains, it might be evidence that a predator had been there. Those holes might not be desirable.

During spring, when nest competition is the fiercest, the researchers set up pairs of nesting boxes. One box contained white feathers. The other either contained no feathers or black feathers. Inside the boxes, black feathers were more difficult to see than white ones. Using video cameras, the researchers spied on how tree swallows, blue tits, and pied flycatchers reacted to the boxes. They watched how long birds waited to explore a nest box. When birds took longer to enter, that suggested the birds were scared.

Birds of all three species hesitated to enter boxes with white feathers. But when feathers were in front of a nest, birds jumped right up and grabbed them. That suggested that birds weren’t afraid of the feathers themselves.

“It was really interesting to discover that birds were using a trick to help them keep their nests,” Wiebe says. “When a bird leaves its nest to search for food, it opens the door for a nest stealer. But if it can buy a little time by scaring away intruders (不速之客) with these feathers, then it has a better chance of coming back in time to defend its nest site.”

【推荐1】The largest genetic study of mosquitoes has found their ability to resist insecticides(杀虫剂) is evolving rapidly and spreading across Africa, putting millions of people at higher risk of contracting malaria（疟疾）.

British scientists who led the work said mosquitoes’ growing resistance to control tools such as insecticide-treated bed nets and insecticide spraying, which have helped cut malaria cases since 2000, now threatens “to disturb malaria control” in Africa.

“Our study highlights the severe challenges facing public efforts to control mosquitoes and tomanage and limit insecticide resistance,” said Martin Donnelly of the Liverpool School of Tropical Medicine, who worked on the study with a team from Britain’s Wellcome Trust Sanger Institute.

Latest World Health Organization (WHO) data show that 216 million people were infected last year with the malaria parasite（寄生虫）, which is transmitted by blood-sucking Anopheles mosquitoes. The disease killed 445,000 people in 2016, and the majority of them were children in sub-Saharan Africa.

To understand how mosquitoes are evolving, the researchers sequenced the DNA of 765 wild Anopheles mosquitoes taken from 15 locations across eight African countries. Their work, published in the journal Nature on Wednesday, created the largest data resource on natural genetic variation for any species of insect.

Analyzing the data, the scientists found that the Anopheles gamblae mosquitoes（冈比亚疟蚊）were extremely genetically diverse compared with most other animal species. This high genetic diversity enables rapid evolution, they said, and helps to explain how mosquitoes develop insecticide resistance so quickly.

The data also showed the rapid evolution of insecticide resistance appeared to be due to many previously unknown genetic variants（变体）within certain genes. The scientists said these genetic variants for insecticide resistance were not only emerging independently in different parts of Africa, but were also being spread across the continent by mosquito migration.

Michael Chew, an expert at Britain’s Wellcome Trust global health charity which helped fund the research, said the finds underlined the importance of pushing scientific research ahead to control malaria.

Global efforts to control malaria through effective vaccine, insecticides and the best drug combinations require urgent, united action by scientists, drug companies, governments and the WHO.