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北美狼獾瀕臨滅絕 氣候變遷是推手


摘譯自2013年2月4日ENS美國,科羅拉多州,丹佛市報導;沈瑞筠編譯;蔡麗伶審校
在法院給予的最後期限,美國魚類暨野生動物管理署2月4日提案將北美狼獾(North American wolverine)納入《瀕危物種法》的受威脅物種。


美國非營利組織「生物多樣性中心」2011年與官方達成和解協議,要求美國魚類暨野生動物管理署對包含狼獾在內的757種物種做出保護決策,法院要求在這個財政年度內必需有決議。

在美國下48州境內估計只剩250-300隻狼獾,管理署表示,20世紀初時大範圍的獵殺及毒殺導致狼獾幾近滅絕後,狼獾的數量有回升,但目前對牠們生存最大的威脅為氣候變遷。

身為鼬屬(weasel family)陸域最大的成員,狼獾非常依賴接近林線的高山環境,該區終年氣候寒冷且直到五月都還有覆雪。

魚類暨野生動物管理署在提案聲明稿中表示:「眾多氣候模式指出,因氣候暖化之故,狼獾偏好的積雪棲地在未來幾年將會大大的減少及破碎化,並將對這個物種的生存造成威脅。」

生物多樣性中心的瀕危物種主任Noah Greenwald表示:「狼獾因可獵殺比牠大數倍的獵物而聲名遠播,但這卻無助於牠們適應氣候變遷,整個美國西部地區的春雪都在縮小。」他形容狼獾為「凶猛、孤獨的獵者」。

Greenwald認為:「狼獾依賴春季的積雪作為巢穴,因而氣候變遷對牠們造成嚴重威脅。」

魚類暨野生動物管理署表示,超過5英尺持續、穩定的積雪似乎為狼獾生產巢穴的必要條件,因為它提供幼崽安全的環境且隔絕寒冷的冬天。

然而,魚類暨野生動物管理署並沒有考慮諸如雪地摩托車、越野滑雪等活動,及土地管理行為如木材採伐和基礎設施建設等對狼獾構成重大威脅。結果是雖然魚類暨野生動物管理署將狼獾納入《瀕危物種法》的受威脅物種,但這些危及狼獾的活動將會繼續且不會停止或受到控管。

蓄意獵殺狼獾的行為將被禁止。管理署正試圖確認,禁止因合法捕獵其他物種導致誤殺狼獾是否合宜,尋求各州是否有適當的計畫來最小化誤補狼獾的可能性。

管理署山地草原地區負責人Noreen Walsh指出,「這項提案將使我們能夠靈活地給予狼獾的保護,瀕危物種法只提供給那些一定需要被保護的對象。」她表示,「科學證據假設暖化的氣候會大幅降低狼獾的適棲雪穴;在我們致力於提案確保狼獾續存的同時,我們期待聽到來自州或在地的參與者,及公眾、科學界的成員的建言。」

從2月4日起90天的期限中,公眾及利益相關者可投書表達對這些提案的意見。與此同時,管理署將尋求科學界的同儕評審,以確保最後的決議奠基於「硬科學」(solid science)。

管理署將根據最佳可得的科學證據,在一年內做出是否將狼獾納入《瀕危物種法》的受威脅物種的最後決定。管理署也將決定是否指定狼獾的重要棲息地,這樣的指定在氣候變遷的威脅下將有利於狼獾及其​​棲息。

管理署同時提案在該法10(j)節加入一項特別條款,以推動引入狼獾至科羅拉多州過去曾有記載狼獾棲息處。這項提案仍待考量,未來若執行將由科羅拉多公園及野生動物部門主導重新引入。

美國下48州超過90%的狼獾棲地是在聯邦土地範圍,剩下的分屬州、私人或部落持有的土地內。

近來,狼獾主要分佈在華盛頓州的北喀斯喀特山脈及蒙大拿、愛達荷、懷俄明州的洛磯山脈及奧勒岡州的部分地區。已知有一隻雄狼獾居住在內華達山脈及另一隻雄性個體棲息於南洛磯山脈,這兩隻個體都是最近遷移到現居地的。

Climate Change Pushes Wolverine Toward Threatened Species List
DENVER, Colorado, February 4, 2013 (ENS)
Under a court-ordered deadline, the U.S. Fish and Wildlife Service today proposed to protect the North American wolverine as a threatened species under the Endangered Species Act.

In 2011 the nonprofit Center for Biological Diversity reached a settlement agreement requiring the Service to make protection decisions for 757 species, including the wolverine, which the court ordered must get a decision this fiscal year.

Estimating that 250 to 300 wolverines remain in the lower 48 states, the Service says the species had rebounded after broad-scale predator trapping and poisoning programs led to its near extinction in the early 1900s. Now the threat to their survival is climate warming.

The largest terrestrial member of the weasel family, the wolverine is dependent on areas in high mountains, near the tree-line, where conditions are cold year-round and snow cover persists well into the month of May.

"Extensive climate modeling indicates that the wolverine's snowpack habitat will be greatly reduced and fragmented in the coming years due to climate warming, thereby threatening the species with extinction," the Service said Friday in a statement announcing the proposal.

"The wolverine has a reputation for killing prey many times its size, but it's no match for global climate change, which is shrinking spring snowpack across the West," said Noah Greenwald, the Center's endangered species director, who describes the mammals as "fierce, solitary hunters."

"Their dependence on persistent spring snowpack for denning makes them severely threatened by climate change," said Greenwald.

Persistent, stable snow greater than five feet deep appears to be a requirement for natal denning, because it provides security for offspring and buffers cold winter temperatures, the Service says.

Nevertheless, the Service does not consider activities "such as snowmobiling and backcountry skiing, and land management activities like timber harvesting and infrastructure development, to constitute significant threats to the wolverine."

As a result, the Service is proposing a special rule under the Endangered Species Act that, even if the wolverine is listed as a threatened species these types of activities would be allowed to continue and would  not be prohibited or regulated.

However, intentional killing of wolverines would be prohibited.   The Service is seeking input on whether or not it is appropriate to prohibit incidental take of wolverine in the course of legal trapping activities directed at other species, if states have programs in place to minimize the chances of this occurring.

"This proposal would give us the flexibility to tailor the protections for the wolverine provided by the ESA to only those things that are necessary," said Noreen Walsh, director of the Service's Mountain-Prairie Region.

"Scientific evidence suggests that a warming climate will greatly reduce the wolverine's snowpack habitat," Walsh said. "We look forward to hearing from our state and local partners and members of the public and scientific community on these proposals as we work to ensure the continued recovery of the species."

A 90-day comment period, beginning today, is being provided to allow the public and stakeholders an opportunity to comment on these proposals.  During that time, the Service will seek peer review from qualified members of the scientific community to ensure that our final decision is based on solid science.

The Service will make a final determination a year from now on whether to add the wolverine to the Federal List of Endangered and Threatened Wildlife based on the best available science. The Service will also decide whether or not it is prudent to designate critical habitat for the wolverine, and whether such a designation would be beneficial to this species given the threat to its habitat is climate change.

The Service is simultaneously proposing a special rule under Section 10(j) of the ESA that would facilitate reintroduction of the species to its historical range in Colorado. The reintroduction effort, which is still under consideration, would be led by the Colorado Department of Parks and Wildlife.

More than 90 percent of wolverine habitat in the Lower 48 states is located on federally-owned land; the rest is on state, private or tribally owned land.

Currently, wolverines occur within the North Cascades Range in Washington and the Northern Rockies of Montana, Idaho, Wyoming and a small portion of Oregon.

One individual male wolverine is known to inhabit the Sierra Nevada and one male wolverine resides in the southern Rocky Mountains. Both are recent migrants to these areas.

Wolverines once existed also in the Sierra Nevada of California and the southern Rocky Mountains in the states of Colorado, Wyoming, and New Mexico.

※ 全文及圖片詳見:ENS