来源：《科学美国人》2022年4月号
Rachel Carson’s classic best seller about ecological threats, Silent Spring, started a wave of American environmentalism. It played a direct role in the 1972 decision by the newly formed U.S. Environmental Protection Agency to ban use of the pesticide DDT. It will be 60 years ago this June that the public was introduced to Carson’s arguments, as her book chapters were serialized in the New Yorker magazine. The coming anniversary makes this a good time to consider whether the book achieved one of her major goals: protecting wildlife and, in particular, birds.
蕾切尔·卡森关于生态威胁的经典畅销书《寂静的春天》掀起了美国环保主义的浪潮。它在1972年成立不久的美国环境保护署禁止使用杀虫剂滴滴涕(DDT)的决定中发挥了直接作用。60年前的6月，当卡森的书以章节的形式在《纽约客》杂志上连载时，公众开始了解她的观点。即将到来的周年纪念是一个很好的时机来考虑这本书是否达到了她的一个主要目标：保护野生动物，特别是鸟类。
Carson took a complex technical subject—the damaging effects of persistent pesticides—and expressed it in one simple, poetic image: a spring in which no birds sang. She asked us to imagine what it would be like to awaken in the morning to a world without these songs. She wrote with grace, and she made us feel the loss. But how well have we acted on Carson’s warnings?
卡森研究了一个复杂的技术主题——持久性杀虫剂的破坏性影响，并用一个简单而富有诗意的形象表达了这一主题：一个没有鸟儿歌唱的春天。她让我们想象一下，如果早晨醒来，看到一个没有鸟叫声的世界，会是什么样子。她写得很优雅，让我们感到失落。但我们对卡森的警告采取了多少行动呢？
With some exceptions, we haven’t been very successful, and neither have birds. In 2019, a major study showed that 29 percent of North American birds have vanished since 1970. The study was notable because of its sweep: it integrated data across scores of species and the different biomes birds live in, and it used a variety of approaches to validate its counts; an article published by the Audubon Society called the result “a sobering picture” of widespread avian decline. Grasslands were the hardest hit, with a documented loss of more than 700 million breeding individuals—a decline of more than 50 percent. But major declines occurred in every biome save wetlands and in nearly every species.
除了一些例外，我们并没有取得很大的成功，鸟类也如此。2019年，一项重大研究表明，自1970年以来，29%的北美鸟类已经消失。这项研究之所以引人注目，是因为它的广度：它整合了几十种鸟类和鸟类生活的不同生物群系的数据，并使用了多种方法来验证其计数；奥杜邦协会发表的一篇文章称，这一结果为鸟类普遍减少的“一幅发人深省的画面”。草原是受影响最严重的生物群系，据记录，草原失去了超过7亿只繁殖个体，降幅超过50%。除湿地外的所有生物群系和几乎所有物种都出现了种群大幅下降。
Still, the 2019 bird study, despite its grim results, also suggests that protecting biodiversity is not a lost cause. One important exception in the otherwise bleak picture the study painted is wetlands. There bird abundance increased 13 percent. What distinguishes wetlands from other ecological areas? One answer is that wetlands have been especially shielded from excessive industrial activity for a long time. The areas have been under a host of legal protections on the federal, state and tribal level. Some of these laws prioritized wetlands for their diverse ecological value. Others safeguarded such areas because they are important to navigation and commerce, fisheries, flood control and water supplies.
尽管2019年的鸟类研究结果令人沮丧，但它也表明，保护生物多样性并非注定失败。在这项研究所描绘的黯淡图景中，一个重要的例外是湿地。那里的鸟类数量增加了13%。湿地与其他生态区域的区别是什么？一个原因是长期以来，湿地一直受到保护，不受过度工业活动的影响。这些地区一直受到联邦、州和部落层面的一系列法律保护。其中一些法律优先考虑湿地的多样性生态价值。其他法律保护这些区域，因为它们对航运、商业、渔业、防洪和供水至关重要。
The other encouraging exception in the bird study was raptors, a group that includes the majestic bald eagle. Raptor numbers have increased by 15 million individuals. Bald eagles were on the verge of extinction at the time Carson wrote, but they recovered in large part as a result of the ban on DDT. A news story published by the Audubon Society notes that “the numbers show that taking steps like wildlife management, habitat restoration and political action can be effective to save species.” Scientists have documented the current threat to biodiversity. Their data also show that if we act on this information, we can change the outcome.
鸟类研究中另一个令人鼓舞的例外是猛禽，包括雄伟的白头海雕。猛禽数量增加了1500万只。卡森写《寂静的春天》时，白头海雕已濒临灭绝，它们的恢复在很大程度上是由于对DDT的禁令。奥杜邦协会发表的一篇新闻报道指出，“这些数字表明，采取野生动物管理、栖息地恢复和政治行动等措施可以有效地拯救物种。”科学家们已经记录了当前对生物多样性的威胁。他们的数据还表明，如果我们根据这一信息采取行动，我们可以改变结果。