“They are our guests,” Ghulam Mohiuddin Dar said on an extremely cold day as he and his colleagues broke the ice and dropped grain at bird feeding points on the Hokersar wetland in Kashmir.

Dar and his colleagues are hired by the local government to feed the hungry birds as weather conditions in the region became worse. “Since December, temperatures have dropped to—10℃ and there have been two heavy snowfalls, which have blanketed the vast rice fields and fruit farms in the area. Scores of wetlands and lakes, including parts of the famous Dal Lake, have been covered up by thick ice in Kashmir,” Dar added.

The cries of hundreds of thousands of birds that visit Kashmir during their winter migration (迁徙) have long been a welcome noise for the locals. They arrive from as far away as eastern Europe, Japan and Turkey to feed and produce babies in the wetlands. Officials say at least 700, 000 birds have moved to Kashmir in the past two months and expect more to arrive as temperatures improve in February.

In recent decades, the number of visiting birds has declined, which experts say is due to climate change and urban development. “Construction around the Hokersar wetland, poisonous waste and the changing climate in the area are robbing the birds of their traditional watering holes and nesting areas,” Dar explained.

According to a recent study by the University of Kashmir, the Hokersar wetland shrank (缩小) from nearly 19 square kilometers in 1969 to 12.8 square kilometers today. Fortunately, environmental groups and local residents are also joining hands to feed the hungry birds in the icy conditions.

“It’s not just our official duty to feed them but also an order from Nature,” Dar told me.

Ever wondered if dogs can learn new words? Yes, say researchers as they have found that talented dogs may have the ability to grasp new words after hearing them only four times.

While previous evidence seems to show that most dogs do not learn words, unless eventually very well trained, a few individuals have shown some extraordinary abilities, according to a study published in the journal Scientific Reports.

“We wanted to know under which conditions the gifted dogs may learn novel words,” said researcher xuekw Claudia Fugazza from the Eötvös Loránd University in Hungary. For the study, the team involved two gifted dogs, Whisky and Vicky Nina. The team exposed the dogs to the new words in two different conditions.

In the exclusion-based task, presented with seven known toys and one new toy, the dogs were able to select the new toy when presented with a new name. Researchers say this proves that dogs can choose by exclusion when faced with a new word, they selected the only toy which did not have a known name.

However, this was not the way they would learn the name of the toy. In fact, when they were presented with one more equally new name to test their ability to recognize the toy by its name, the dogs got totally confused and failed.

The other condition, the social one, where the dogs played with their owners who pronounced the name of the toy while playing with the dog, proved to be the successful way to learn the name of the toy, even after hearing it only 4 times. “The rapid learning that we observed seems to equal children’s ability to learn many new words at a fast rate around the age of 18 months,” Fugazza says. “But we do not know whether the learning mechanisms(机制) behind this learning are the same for humans and dogs. ”

To test whether most dogs would learn words this way, 20 other dogs were tested in the same condition, but none of them showed any evidence of learning the toy names, confirming that the ability to learn words rapidly in the absence of formal training is very rare and is only present in a few gifted dogs.

Bees are unimaginably territorial（地盘意识强的）, fighting to death to defend their home with painful stings (螫刺). But killer bees are particularly fierce. They appeared after African bees were imported to Brazil in the 1950s. By the 1980s, they had spread north to the United States, outgunning native bees along the way. Their massive attacks have killed more than 1,000 people.

Mario Palma, a biochemist at Sao Paulo State University in Brazil, who studies social behavior in bees, wanted to understand the basis of this aggression. So he and his colleagues swung a black leather ball in front of some killer bees and collected the bees whose stingers got stuck in the ball during the attack. They also collected killer bees that remained in the cell. The analysis suggested that killer bee brains have two proteins that—in the aggressive bees—quickly break into pieces to form a so-called “neuropeptide( 神 经 肽 )”, they reported this week in the Journal of Proteome Research.

Palma and his colleagues already knew that bee brains have these two proteins. “We were astonished when we identified some very simple neuropeptides, which were produced in a few seconds,” Palma said. Killer bees that remained in the cell did not make these neuropeptides, he reported. And when his team put these neuropeptides into young, less aggressive bees, they “became aggressive like older individuals”.

Palma added that these neuropeptides also increase the production of energy and alarm chemicals. They could also encourage the nerve cells in killer bees needed to make the stinging attack. “There is a fine biochemical regulation in the killer bee brain,” he said. Researchers have found these neuropeptides in other insects, but few had associated them with “fight” behavior.