Australian cities can keep their native wildlife — but only if they can kick their habit of urban sprawl (无计划的扩展). That’s the finding of a new study by leading Australian environmental researchers Jessica Sushinsky, Professor Hugh Possingham and Dr. Richard Fuller of the University of Queensland.

“While urban development usually reduces the number of birds in a city, building more compact (紧凑的) cities and avoiding urban sprawl can slow these reductions greatly,” says lead author Jessica Sushinsky. “Compact housing development leaves birds’ homes untouched, leading to fewer losses of birds.”

The researchers surveyed native and wild birds in Brisbane’s urban areas, including living and industrial areas, public parks and gardens, major roadways and airports. They then used statistical modeling to find out what will happen to the birds as the city grows. The first setting was compact growth — where multiple homes are built on land that previously had only one house. The second setting was sprawling growth — a familiar pattern where homes are built here and there beyond the city’s current boundaries.

The team’s forecasts showed that a much greater diversity of species was lost over 20 years in the sprawling setting compared to the more compact setting. “Urban sprawl resulted in the disappearance of many urban-sensitive birds — birds that only live in areas where there is native vegetation(植被), such as parklands and woodlands,” Ms. Sushinsky says.

“On the other hand, we found the city with the compact development attracted more birds because it kept more of its parks and green areas.”

Now the Queensland Government has adopted the more compact urban growth strategy, which, Dr. Richard Fuller says, is good news for Australia’s native birds. These birds are environmental specialists — they need a particular environment to do well. “While compact development means smaller backyards, it can also make our entire cities more bio-diverse,” according to Dr. Fuller. “The study shows that we should hold on to our green spaces instead of clearing them for sprawling development.”

This is the first time science has modeled the effects of different urban growth strategies on birds, the researchers say. “Statistical models like these are important because they help us to understand the ecological consequences of a particular decision,” says Dr. Fuller.

Dogs are often known as man’s best friend—but in one beautiful instance, a man ended up being a best friend to a group of pets in need after a dangerous situation nearly became tragic (悲惨的).

Keith Walker, an Atlanta-based homeless man, could have run in the other direction when he saw local animal shelter W-Underdogs on fire. But he ran towards the fire instead and saved all the animals caught inside, though he was in great danger himself.

“I was nervous; I’m not going to lie. I was really scared to go in there with all that smoke. But my heart put me there to save those animals,” Walker said.

“If you love a dog, you can love anyone in the world. My dog is my best friend, and I wouldn’t be here without him, so I knew I had to save all those other dogs.”

The shelter is currently greatly wrecked by the fire and it couldn’t safely inhabit the dogs, says founder Gracie Hamlin, so all the animals have been safely moved to another shelter.

“He is my guardian angel,” Hamlin said. “Even the firefighters didn’t want to deal with the dogs. They called animal control, but Keith was already in the building pulling out the cats and dogs until they were all safe.”

Hamlin and Walker had already known each other because Walker, who has been homeless since he was 13, keeps his own dog, a pitbull (斗牛犬) named Bravo, at the shelter every night.

In fact, Walker came across the fire when he was on his way to pick up Bravo to take him for a walk. And that was how he was able to rescue all the animals—6 dogs and 10 cats.

Before you look down on homeless persons, remember that they are people just like you—and some of them are great, like Keith Walker.