人類發(fā)出的噪音——從交通的喧鬧聲到重機(jī)械的咆哮聲——對(duì)于鳥類是有害的，是因?yàn)樵诟咴胍舻貐^(qū)發(fā)現(xiàn)的鳥類已經(jīng)越來越少了,，這已經(jīng)不是什么秘密了,。
然而有一些物種，特別是那些吟唱低調(diào)歌曲的大型鳥類,，如西部唐納雀,，卻特別容易受到人造噪音的折磨。
美國(guó)博爾德市科羅拉多大學(xué)的動(dòng)物學(xué)家Clinton D. Francis和同事日前在《科學(xué)公共圖書館—綜合》上報(bào)告了這一研究成果,。
研究人員計(jì)算了位于美國(guó)新墨西哥州北部響尾蛇峽谷野生動(dòng)植物保護(hù)區(qū)內(nèi)的鳥類和鳥巢數(shù)量,，這一地區(qū)毗鄰著數(shù)以千計(jì)的天然氣井，其中大多數(shù)都安裝了不停咆哮的壓縮機(jī)——想一想聆聽15米開外的摩托車的感覺,。
在對(duì)從黑頜蜂鳥到北美哀鳩的30余種鳥類進(jìn)行調(diào)查后,，研究人員發(fā)現(xiàn)，更大型的鳥類——例如北美哀鳩和西部唐納雀——會(huì)遠(yuǎn)離這些噪音,。
研究人員表示,，這些大型鳥類可能是被迫離開這些吵鬧的地區(qū)的，這是因?yàn)樾[的機(jī)械淹沒了它們低沉的叫聲,，從而使得鳥類很難聽到彼此的叫聲,。
而體型較小的鳥類——例如褐斑翅雀鹀——則會(huì)唱出一些高調(diào)的歌曲，這些物種似乎沒有受到影響,，這或許是因?yàn)樗鼈兊慕新曇廊荒軌蛏w過機(jī)械的轟鳴,。
研究人員指出,，從物理學(xué)的角度來看,，噪聲是發(fā)聲體做無規(guī)則振動(dòng)時(shí)發(fā)出的聲音,。從環(huán)境保護(hù)的角度看，凡是妨礙到人們正常休息,、學(xué)習(xí)和工作的聲音,，以及對(duì)人們要聽的聲音產(chǎn)生干擾的聲音，都屬于噪聲,。作為一種引起人煩躁,、或因音量過強(qiáng)而危害人體健康的聲音，噪聲對(duì)動(dòng)物的危害同樣不容小覷,。（生物谷 Bioon.com）
doi:10.1371/journal.pone.0027052
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PMID:
Noise Pollution Filters Bird Communities Based on Vocal Frequency
Clinton D. Francis, Catherine P. Ortega, Alexander Cruz
Background Human-generated noise pollution now permeates natural habitats worldwide, presenting evolutionarily novel acoustic conditions unprecedented to most landscapes. These acoustics not only harm humans, but threaten wildlife, and especially birds, via changes to species densities, foraging behavior, reproductive success, and predator-prey interactions. Explanations for negative effects of noise on birds include disruption of acoustic communication through energetic masking, potentially forcing species that rely upon acoustic communication to abandon otherwise suitable areas. However, this hypothesis has not been adequately tested because confounding stimuli often co-vary with noise and are difficult to separate from noise exposure. Methodology/Principal Findings Using a natural experiment that controls for confounding stimuli, we evaluate whether species vocal features or urban-tolerance classifications explain their responses to noise measured through habitat use. Two data sets representing nesting and abundance responses reveal that noise filters bird communities nonrandomly. Signal duration and urban tolerance failed to explain species-specific responses, but birds with low-frequency signals that are more susceptible to masking from noise avoided noisy areas and birds with higher frequency vocalizations remained. Signal frequency was also negatively correlated with body mass, suggesting that larger birds may be more sensitive to noise due to the link between body size and vocal frequency. Conclusions/Significance Our findings suggest that acoustic masking by noise may be a strong selective force shaping the ecology of birds worldwide. Larger birds with lower frequency signals may be excluded from noisy areas, whereas smaller species persist via transmission of higher frequency signals. We discuss our findings as they relate to interspecific relationships among body size, vocal amplitude and frequency and suggest that they are immediately relevant to the global problem of increases in noise by providing critical insight as to which species traits influence tolerance of these novel acoustics.
