About a billion birds die from flying into buildings each year in North America. Suspicions have been that birds may regard the open areas behind glass as safe passageways. Or they may mistake the reflected trees for the real thing.

Researchers would like to reduce collisions, which requires a solid understanding about what makes a bird more or less likely to die by crashing into a building in the first place.

“There was relatively little known at a broad scale. Previous studies were at one small study site.'' Jared Elmore, a graduate student in natural resource ecology and management at Oklahoma State University. So he and his colleagues used a previously created data set of building collisions for birds at 40 sites throughout Mexico, Canada and the U.S.

The first finding was obvious: bigger buildings with more glass kill more birds. But the details were more remarkable. "We found that life history predicted collisions. Migrants(候鸟), insect-eaters and woodland-inhabiting species collided more than their counterparts(同类).”

Most migratory species travel at night, when lights near buildings can distract or disorient(使迷失方向)them. And Elmore thinks that insect-eating birds might be attracted to buildings because their insect prey(猎物)is attracted to the lights. He suspects that woodland species get tooled by the reflections of trees and bushes in the windows. The results are in the journal Conservation Biology.

By understanding which birds are more likely to collide with buildings, researchers can perhaps determine the best way to adapt buildings, or their lighting, to help prevent such accidents. And by knowing risks, along with migration timing and behavior, building managers can better predict when birds are at their greatest danger - and improve lighting strategics accordingly.

Elmore's next project will use radar to help predict bird migrations. " I think that would maybe go a long way in terms of providing information to people, to the public, to building managers, on when they can get the most benefit in terms of lights-out policies."

Brown bears have stopped eating salmon（鲑鱼）in favor of elderberries after being forced to make a choice due to climate change. Warming temperatures mean that the berries are ripening earlier than usual, at exactly the same time as the freshwater streams on Alaska’s Kodiak Island are over flowing with salmon.

The island’s brown bears typically feed first on salmon in early summer, followed by elderberries later in the season, in late August and September.

“What you have is a scrambling of the schedule,” said William Deacy, a biologist at Oregon State University that studied the phenomenon.

“It’s essentially like if breakfast and lunch were served at the same time and then there is nothing to eat until dinner. You have to choose between breakfast and lunch because you can only eat so much at a time.”

The study found that during the unusually warm summer of 2014, the bears, which would traditionally kill up to 75 percent of the salmon, were nowhere to be seen near the streams. Instead, they were in the hills busy munching on berries, which contain less protein and therefore take less energy to break down, causing them to gain weight more quickly.

Biologists warned that changes caused by a warming planet were behind the bears’ unusual behavior and could affect the entire ecosystem.

The researchers found that the forests around the streams suffered because the bears’ fish carcasses（残骸）were no longer there to enrich the soil.

“Bears switched from eating salmon to elderberries, disturbing an ecological link that typically fertilizes the ecosystems and generates high death rates for salmon,” the study said. On average, red elderberries are said to be ripening two and a half days earlier every decade. If the pattern continues, they will regularly overlap（重叠）with the salmon by 2070.

According to the Keep Sweden Tidy Foundation, over a billion cigarette ends are left on Sweden’s streets every year which account for about 62 percent of all litter. Teaching humans not to throw cigarette ends on the street has so far proven impossible, but a Swedish startup claims it can teach crows (乌鸦) to pick up after us and save local communities millions of krone in cleaning fees every year. Corvid Cleaning teaches wild crows to do our dirty work through a step-by-step learning process, which involves rewarding the birds with food for every cigarette end they collect.

Basically, the birds are first trained to associate cigarette ends with food, and then a food dispenser (分配器) that only drops food when the bird arrives is introduced. Then, by taking the food rewards away, trainers encourage investigation, so that the crows start pecking on the machine eventually hitting a button that causes the food to drop. This opens the way to the fourth step, where the birds discover that the reward drops only when they put cigarette ends in an assigned container.

It sounds complicated, but crows are among the smartest birds on Earth, and such training programs have proven successful several times in recent years. In fact, Corvid Cleaning is so confident it can pull it off that it has expressed interest in testing it massively, in the town of Södertälje.

The novel approach to litter cleaning has gotten positive feedback online, but there are those who consider the ethical (伦理的) implications of this project. The very fact that we can train crows to pick up cigarette ends, but we can’t get humans not to throw them away is hard to accept. Plus, there are the health implications of constantly exposing the birds to the toxins in cigarette ends, and the risk of making them reliant on the food dispensers.