棲地流失、環境變遷威脅 美國1/3鳥類亮警訊 | 台灣環境資訊協會-環境資訊中心

棲地流失、環境變遷威脅 美國1/3鳥類亮警訊

2009年03月24日
摘譯自2009年3月19日ENS美國,華府報導;薛郁欣編譯;蔡麗伶審校

I'iwi是一種夏威夷的鳥類,屬於易為滅絕的物種;攝影:Jack Jeffrey ;圖片提供:美國內政部。最近一份最完整的美國鳥類報告書顯示,超過800種鳥類物種中有近1/3受到環境變遷、棲地流失、外來物種的影響而瀕臨滅絕。

19日由美國內政部長沙拉薩 (Ken Salazar) 發布的這份報告, 是由美國漁業與野生動物署( U.S. Fish and Wildlife Service )、 美國地質調查局( U.S. Geological Survey ) 、州政府野生動物局、以及非政府組織共同合力完成。

「就如50年前瑞秋卡森撰寫的《寧靜的春天》一樣,今日鳥類是大地 、水資源與生態系統健康的警鐘,」沙拉薩說明,「從新英格蘭的岸鳥、密西根的鶯、夏威夷的鳴禽,我們正目睹著備受威脅而數量持續下降的現象,而應該敲起環境警鐘。我們需要一起努力,確保不會在自己的森林、田野、後院裡感到死寂,就像是瑞秋卡森曾經警告過的。」

夏威夷為美國鳥類物種流失最多的地區。在夏威夷,有超過 1/3 的鳥類已列於瀕危物種法案上。自西元 300 年於此地拓墾後,已有 71 種鳥類滅絕、另有 10 種已經消失 40 年,而很可能早已滅絕。

自然保育組織夏威夷分會( The Nature Conservancy of Hawaii )科學暨文化資深顧問岡博士(Dr. Sam Gon III)表示,太多的夏威夷鳥類生存在邊緣,此時正需要經濟支援,用來因應破壞與原始棲地流失等主要威脅。

「為了控制棲地流失與環境退化,以及受到疾病與外來物種入侵等直接威脅,應考量一個英雄般的努力,並以更多支持針對夏威夷的棲地保育。」岡博士說。

西部草鷚,一種草原鳥類,因數量減少而在1929年被指定為國家保育類動物;攝影:John and Karen Hollingsworth ;圖片提供:FWS「在原生森林中早已證明,當我們正努力穩定棲地恢復一個物種的同時,更多同時是讓這片棲地的其他物種都能共享其成。」

這份報告呼籲對保育稀有鳥類的夏威夷森林給予更大的支持,並消除外來掠食物種、先捕捉正在繁衍的物種以避免他們面臨滅絕的威脅。

其他地方的鳥類也有危險。草原鳥類是另一群快速消失的物種,其中 48% 鳥類物種已列於保育,55%的鳥類數量明顯下降。

對生物燃料的需求量增加之後,減少了農場復育計畫的範圍。如果沒有適當的風力發電位址,也會造成草原碎裂、影響鳥類築巢活動。這一類的例子如: 小草原松雞。

全球暖化預期會增加乾旱的可能,而減少草原生產力,致使鳥類減少食物來源。然而,而改變草原作為農業利用、注入除蟲劑、以及其他化學污染等,都已經破壞了鳥類棲地。

外來植物與動物是主要的威脅,例如家貓與流浪貓每年殺害數千萬鳥類。類似海鳥等島嶼鳥類,更因為在地面上築巢習性,引來老鼠、狐狸、貓、狗、 棕蓑貓等的捕食。

美國城市、郊區、與商業發展速率越來越快,已經威脅到每個主要的棲地完整、並造成溼地接受自然河水補足的功能、破壞沿海鹽水草澤、並造成森林、莽原、草原等的破碎與死亡。鳥類也因碰撞建物而死亡。

大部分美國森林生態系統都已經受到伐木、道路、實驗林、以及林火抑制防火道的興築而破碎。美國近大西洋的西北部有超過85%的老熟林都已經開發,使得仰賴老熟林環境的北美斑點梟以及斑海雀都已面臨滅絕壓力。

西岸較乾旱的地區已有30%鳥類數量正在下降、過度放牧也使草原生產力下降、並造成河岸地區的植被裸露,也因此鳥類覓食與生育的棲地消逝。海洋的過度捕撈也促使鳥類飢餓與築巢失敗。

不過,這份報告提出那些受到棲地復育及保育的地區,出現物種數量增加的現象,特別是水鳥。這項結果顯示一個雀躍的希望,正是保護那些凋零的族群的方式可能是有用的。

美國鳥類現況》(2009 U.S. State of the Birds Report)整合了將近 40 年以來 3 個長期鳥類族群調查資料,這份資料則由數千名市民科學家與專業生物學家所完成的。

在這場記者會當中,來自康乃爾鳥類研究室的費茲派翠克(John Fitzpatrick)形容這次報告的產出是靠「居民與科學的交會」,獲得了全場的笑聲。他說:「這篇報告的數據並不是由少數無用的科學家收集的,而是由數十萬發現科學有趣的個人參與所貢獻而來。每年只要花上幾分鐘,我們就能夠開始建立起一個龐大的資料庫,不僅顯示出廣泛的科學資料,也包括更小的棲地資訊!因此,我們才能蒐集到更龐大的資料。」

這些數據由美國地質測量局與加拿大野生動物部所執行的北美鳥類繁殖調查而來( North American Breeding Bird Survey)。這項計畫自1968年開始,在超過4000個區域,由志工參與觀察365個物種所共同完成的。

此報告以國家奧杜邦學會( National Audubon Society)對聖誕節鳥類計數方式( Christmas Bird Count )描述120種在美國渡冬的候鳥數量趨勢。

於羅里達州的木鸛一影,亦為聯邦政府列為瀕危物種之ㄧ;攝影:Mehmet Karatay而針對 13 種水鳥的趨勢則由美國漁業與野生動物服務部與加拿大野生動物部( Canadian Wildlife Service )由先驅與野生動物學家進行水鳥生育族群與棲地調查。

「鳥類是提醒我們有關棲地破壞、環境變遷、過去短視近利環境政策的醒鐘,而這些破壞造成了嚴重後果。我們必須向各個層次的政策與實地行動,強調氣候暖化與主要棲地的流失的嚴重性。」國家奧杜邦學會主席福歷可(John Flicker)說。

「這份報告清楚強調亟需個體、合作體、政府的行動,開始行動就能有所改變。一起努力,我們可以救援,不只是我們的鳥類、而是支持我們整體的環境。」他說。

「奧杜邦以往便傳達這樣的訊息,而今,感謝所有在2009年美國鳥類現況報告中參與的每份子。在加入國會議員、聯邦政府、保守黨立法委員的協助之前,鳥類的警告會比以往讓更多美國人關注到。」

美國漁業與野生動物署會在歐巴馬政權之下獲得比布希政府時代受到更多的經濟支援。「當我們回顧過去十年,內政部預算持續減少,直到成為聯邦機構預算支援最少的部門。這影響了漁業與野生動物的執行,因為他們沒有經費完成工作。」他說。

「振興經濟方案補助魚類與野生動物服務,這筆經費會在下幾個星期就能夠上路。」沙拉薩承諾。

美國鳥類保育協會思洛德(Darren Schroeder)說:「 花費在鳥類保育上的經費會經由更廣大的受益者回饋,賞鳥活動每年對經濟收入貢獻了450億美元,但這些鳥類卻正在減少。1/3的夏威夷鳥類列名瀕滅名單上,但過去的行政經費只佔了ESA物種恢復經費的4%。」

秘書長沙拉薩說對瀕危鳥種的列名與否將由科學家決定,「科學家會給予我們方向,」他說這項報告是「行動的響鐘」。他認為歐巴馬政府會負責處理環境變遷這項「艱鉅但必需的行動」。「我們正目睹我們對鳥類物種的影響,歐巴馬總統曾表示,我們會以新的策略對抗氣候變遷。」

U.S. Birds Struggling to Survive Habitat Loss, Climate Change
WASHINGTON, DC, March 19, 2009 (ENS) -

Nearly one-third of the more than 800 bird species in the United States are endangered, threatened or in decline due to climate change, habitat loss, and invasive species, finds the first comprehensive report ever produced on U.S. bird populations.

At a news conference in Washington today, Secretary of the Interior Ken Salazar released the report, which was developed by a partnership among the U.S. Fish and Wildlife Service, the U.S. Geological Survey, state government wildlife agencies and nongovernmental organizations.

"Just as they were when Rachel Carson published "Silent Spring" nearly 50 years ago, birds today are a bellwether of the health of land, water and ecosystems," Salazar said. "From shorebirds in New England to warblers in Michigan to songbirds in Hawaii, we are seeing disturbing downward population trends that should set off environmental alarm bells. We must work together now to ensure we never hear the deafening silence in our forests, fields and backyards that Rachel Carson warned us about."

In Hawaii, more birds are in danger of extinction than anywhere else in the United States. More than one-third of all bird species listed under the Endangered Species Act occur in Hawaii and 71 bird species have gone extinct since people came to the islands in about 300 AD. At least 10 more bird species have not been seen in 40 years and may be extinct.

Dr. Sam Gon III, senior scientist and cultural advisor for The Nature Conservancy of Hawaii, said that too many Hawaiian bird species are on the brink and more money is needed to address the primary cause destruction and loss of native habitat.

"Considering the heroic efforts that are needed to control habitat loss and degradation, as well as direct threats such as disease and invasion by non-native plants and animals, much more support should be directed toward habitat protection in Hawaii," Gon said.

"It's been shown in our native forests, for example, that when efforts are made to stabilize habitat for one species, the benefits are enjoyed by the many species that share that habitat," he said.

The report calls for greater investment to protect remaining Hawaiian forests that shelter rare birds, elimination of invasive predators, and captive breeding of endangered species before they too vanish into extinction.

Elsewhere birds are also in trouble, the report finds. Grassland birds are among the fastest declining birds in North America - 48 percent are of conservation concern and 55 percent are showing significant declines.
High commodity prices and demand for biofuels contribute to reduced acreage for farm conservation programs. Wind turbines, if improperly sited, can fragment grasslands and disrupt nesting activity of birds such as lesser prairie-chickens.

Global warming is expected to increase drought conditions in grassland regions, leading to reduced food for birds. Conversion of grasslands to agriculture has destroyed habitat and pumped pesticides and other toxics into the environment.

Invasive plants and animals are major threats. Domestic and feral cats kill hundreds of millions of birds each year. Island nesting birds, particularly seabirds, are vulnerable since they nest on the ground or in burrows and are preyed upon by rats, foxes, cats, dogs, and mongooses.

The accelerated pace of urban, suburban, and commercial development in the United States threatens the integrity of every major habitat, from continued draining of wetlands and destruction of coastal marshes, to loss and fragmentation of forests, aridlands, and grasslands because of suburban sprawl. Many birds die when they collide with buildings.

Most U.S. forest ecosystems have been fragmented by logging, road building, tree plantations, and fire suppression. More than 85 percent of old-growth forest in the Pacific Northwest has been eliminated, leading to the listing of the Northern spotted owl and marbled murrelet as threatened under the Endangered Species Act.

In arid regions of the West where 30 percent of bird species are in decline, excessive grazing has degraded grasslands and denuded streamside areas where most bird species forage and breed. Overfishing in oceans has led to bird starvation and nesting failures.

Yet, the report finds places where habitat restoration and conservation have reversed previous declines, particularly in waterfowl species, offering hope that action to save vanishing populations might still be effective.

Covering the past 40 years, "The U.S. State of the Birds," synthesizes data from three long-running bird population surveys conducted by thousands of citizen scientists and professional biologists.

At the news conference, John Fitzpatrick from the Cornell Lab of Ornithology earned laughs and agreement from all speakers with his comment that "citizen science rocks."

"Data in this report were collected not by a few pinhead scientists but by millions of individuals who found that science is fun," Fitzpatrick said. "With a few minutes a year we can begin to pull together massive databases that show us not just the broad base but the smaller habitats - we are getting huge amounts of data."

Data comes from the North American Breeding Bird Survey, administered by the U.S. Geological Survey and Canadian Wildlife Service, and conducted at more than 4,000 sites by volunteer observers, providing data for 365 breeding species since 1968.

For 120 species that breed elsewhere but winter within the U.S., the report used trends from the National Audubon Society's Christmas Bird Count.

Trends for 13 waterfowl species were provided by the U.S. Fish and Wildlife Service and Canadian Wildlife Service from the Waterfowl Breeding Population and Habitat Survey, conducted by pilots and wildlife biologists.

"The birds are sending us a wake-up call that the habitat destruction, climate change and shortsighted environmental policies of the past are combining to take a serious toll. We must address the warming of our climate and the loss of vital habitat through policy and on-the-ground action at every level," warned said John Flicker, president of the National Audubon Society.

"This report makes clear the need for urgent individual, collective and government action, and leaves little doubt that taking action can make a difference. Together, we can safeguard not only our birds, but the environment that sustains us all," he said.

"Audubon has sent this message before, and now, thanks to all who played a role in the 2009 U.S. State of the Birds Report, the birds' warning will be heard by more Americans than ever before –  including our representatives in Congress and in our state capitals, and policy-makers in our communities."

Secretary Salazar said the U.S. Fish and Wildlife Service will be better funded by the Obama administration than it had been during the Bush years. "When we look back to last decade you see the Department of the Interior budget continued to decline to be one of bottom end budgets of all federal agencies. This impacts the Fish and Wildlife Service," he said, "because they don't have the funding to get the job done.

"The stimulus package funds the Fish and Wildlife Service, and the money will be out on the ground in the next couple of weeks," the secretary promised.

Money invested in bird conservation will pay back big dividends, said Darren Schroeder of the American Bird Conservancy. "Bird watching contributes $45 billion to our economy every year, but many species are in decline and some are threatened with extinction. One-third of all birds listed under the Endangered Species Act are Hawaiian birds, but under the previous administration they got only four percent of ESA species recovery funds.

Secretary Salazar said the listing and delisting of endangered bird species will be guided by science. "Science will show us the way." He called the report "a clarion call to action."

Salazar said the Obama administration will take on "the difficult but necessary undertaking of dealing with climate change."

"We are seeing we are having impacts on our bird species," the secretary said. "President Obama says we will have a new strategy for climate change for America.