氣候變暖讓灰熊棄葷從素改吃漿果

Grizzly bears have stopped eating salmon in favour of elderberries after being forced to make a choice due to climate change. Warming temperatures meant that the berries are ripening earlier than usual, at exactly the same time as the freshwater streams on Alaska’s Kodiak Island are overflowing with sockeye salmon.

由於氣候變化的影響，灰熊被迫做出艱難抉擇，放棄鮭魚改吃接骨木果。溫暖的氣候使得漿果成熟期提前，與此同時，阿拉斯加科迪亞克島的淡水河流裏也擠滿了紅鮭。

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.

往年，島上的棕熊在夏初先吃了鮭魚，然後在八月末和九月吃接骨木果。

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

研究這個現象的俄勒岡州立大學的生物學家威廉?迪西稱：“如今的生物成熟期十分混亂。”

"It's essentially like if breakfast and lunch were served at same time and then there is nothing to eat until dinner.

“這就好比早餐和午餐同時送上來，那麼晚餐前就什麼都沒得吃了。”

"You have to choose between breakfast and lunch because you can only eat so much at a time."

“你必須在早餐和午餐間做抉擇，因爲你一次只能吃那麼多。”

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.

研究發現，在2014年，夏季異常溫暖，但流水旁卻不見灰熊的蹤影。照往常來說，它們這時候可要吃掉高達75%的鮭魚。

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.

但是，它們一反常態，跑到山上大吃漿果。漿果裏面的蛋白質含量低，消化分解所需能量少，因此它們長胖的速度也加快了。

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

生物學家們警告稱，灰熊不尋常的行爲背後反映的是全球變暖所帶來的變化，可能會影響整個生態系統。

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

研究人員發現，沒有灰熊吃剩的魚骸來給土壤增肥，河流周圍的森林已經受到了影響。

"Bears switched from eating salmon to elderberries, disrupting an ecological link that typically fertilizes terrestrial ecosystems and generates high mortality rates for salmon," the study said.

研究表明：“灰熊不吃鮭魚改吃接骨木果的行爲不僅破壞了滋養陸地生態系統的生態鏈，還促成了鮭魚的高死亡率。”

On average, red elderberries are said to be ripening two and a half days earlier every decade.

據稱，平均每十年，紅接骨木果成熟的時間會提前兩天半。

If the pattern continues, they will regularly overlap with the salmon by 2070.

如果再這樣下去，到2070年，鮭魚和接骨木果的成熟期將會定期重合。

The study was published in the Proceedings of the National Academy of Sciences.

這項研究成果已在《美國科學院學報》上發表。