气候变化让灰熊更具攻击性?

NOAH ADAMS, host: Today marks the beginning of National Parks Week, featuring free admission(免费入场券) through the 24th of April. It's been a tough time for the parks lately, the system is threatened by federal funding cuts, urban development, and climate change. And the effects of climate change are dramatically visible in one of the country's best known national parks. In Yellowstone, the whitebark pine(白皮巴尔干松) trees are affected by the increase in temperature. The whitebark seeds are a basic food for the grizzly bears(灰熊). Last year, grizzlies attacked several visitors, killing two.

Paul Solotaroff writes about it in the April issue of Men's Journal. He believes there's a definite connection.

Mr. PAUL SOLOTAROFF (Writer, Men's Journal): About five, six years ago, arborists(树艺家) begin to notice that these extraordinary trees that have for many, many thousands of years survived winters of 50, 60 below, suddenly were dying and not dying by the handful, but dying by the stand, eaten alive by something called mountain pine beetles(甲虫).

ADAMS: So the beetles, they can - it's not hot enough so they can go to work.

Mr. SOLOTAROFF: They can go to work and they can now spend the winter inside these trees, hatch their larvae(幼虫), survive the winter themselves and attack the trees they've set up shop in and then fly to new trees and eat them alive as well.

ADAMS: Now, tell us about the attacks on the campers in Yellowstone. How many people were killed? How many were injured? What was going on there?

Mr. SOLOTAROFF: Well, there hadn't been a bear-caused fatality in two and a half decades in Yellowstone. And over the course of six weeks, two people were killed. One, a most unfortunate episode in which a botanist(植物学家) was wandering in an area that had just been visited by grizzly bear study team and they'd found a grizzly and they've knocked them out to take hair samples, tooth samples and the like. And they didn't post signs, warning that they were there and it was a bear that had been sedated(安静的). And so this poor guy wandered into a clearing, and there he found the bear waking up. And the bear killed him and ran away.

And then six weeks later, a tragically thin mother bear and her three cubs(幼仔) wandered onto a campsite where they smelled cooking fish and they attacked several campers, and then finally wound up killing and devouring(吞食) an EMT(内科急救专家) from Michigan.

ADAMS: You have a very scary sentence in your article about the hunger of the bears. It is this: So desperate have they become that they run toward gunfire, having learned that hunters leave gut (内脏) piles after a kill.

Mr. SOLOTAROFF: Yeah. It isn't just a lack of whitebark and those fleshy seeds. I mean, bears need to eat 13, 14,000 calories a day to maintain body weight and also fatten up for the four or five months to go to sleep. And if it were only the pine nuts that have become scarce, they probably be able to find a compensating food source.

The problem is that the fish are dying as well. The streams have gotten so warm, because the summers are longer. The runoff from snow is skinnier. Meaning that by July and August, the fish are dying of heat stroke(中暑) essentially. And so bears who could depend upon cutthroat trout(割喉鳟) and brown trout and rainbow trout to pad out their protein diet are now going hungry in trout streams as well. And it's this kind of, you know, deprivation that is turning bears increasingly desperate.

ADAMS: Now, about global warming, we contacted the Park Service. They say there have indeed been bear attacks in the park and, yes, there is a pine beetle infestation(感染), but that these issues are too broad scientifically to connect directly to climate change. How do you feel about that?

Mr. SOLOTAROFF: It's nonsense. Every reasonable scientist, every reasonable arborist, agrees that there is a very tightly-knit connection between the availability of food supply and the behavior of these bears.

Bears are starving, you know? The bear that was captured after killing the EMT from Michigan was grossly underweight as were her three cubs. But what is driving these bears into populated places is hunger, and that hunger derives entirely from the ripple effects(波及效应) of the warming of the last 10 years and the significant but more gradual warming of the last 30 years in the American Northwest.

ADAMS: That is writer Paul Solotaroff. His article on Yellowstone appears in April's issue of Men's Journal.

Thank you, Mr. Solotaroff.

Mr. SOLOTAROFF: A great pleasure.