Biased detection of bird vocalizations affects comparisons of bird abundance among forested habitats
Biased detection of bird vocalizations affects comparisons of bird abundance among forested habitats
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DOI：
10.2307/1370236
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发表时间：
1997-02-01
期刊：
影响因子：
3.1
通讯作者：
Schieck, J
中科院分区：
文献类型：
--
作者：
Schieck, J
对鸟类的社区研究往往依赖于从鸟类发声计数中获得的丰度估计，但并非所有栖息地都能同样检测到发声。我广播9种鸟类的发声，以评估在四个森林栖息地（年轻，成熟，和老白杨为主的森林，和白色云杉为主的森林）之间的鸟类发声检测的偏见，并在广播的高度，广播是否发生在叶片形成之前或之后，广播发声的频率。几乎所有的广播发声都是在距离扬声器50米处检测到的。然而，在100米的扬声器，27%的广播发声未被检测到，检测是最高的白色云杉林，最低的年轻白杨林，和中间的成熟和老白杨林。广播的检测呈负相关的最低频率的发声，广播从冠层比广播从灌木层，和更高的广播前比后叶片形成。我重新分析了从一项研究中获得的丰度数据，该研究涉及在年轻和年老的白杨为主的森林中野生鸟类的点计数。栖息地之间的偏见，在检测的发声有中度的影响，由此产生的措施，鸟类的栖息地偏好。我建议，如果超过50米的检测距离用于鸟类普查内的森林栖息地，那么森林类型之间的比较应谨慎解释，除非研究人员证明，有偏见的检测发声不影响他们的结论。
Community studies of birds often rely on abundance estimates that are obtained from counts of bird vocalizations, yet vocalizations are not equally detectable in all habitats. I broadcast vocalizations for nine bird species to evaluate biases in detection of bird vocalizations among four forested habitats (young, mature, and old aspen dominated forests, and white spruce dominated forests), and in relation to height of the broadcast, whether the broadcast occurred before or after leaf formation, and the frequency of the broadcast vocalization. Virtually all of the broadcast vocalizations were detected at 50 m from the speaker. However, at 100 m from the speaker, 27% of the broadcast vocalizations were not detected and detection was highest in white spruce forest, lowest in young aspen forest, and intermediate in mature and old aspen forests. Detection of broadcasts was negatively related to the minimum frequency of the vocalization, higher for broadcasts from the canopy than for broadcasts from the shrub layer, and higher for broadcasts before than after leaf formation. I reanalyzed abundance data that were obtained from a study involving point counts of wild birds in young and old aspen-dominated forest. Biases among habitats in the detection of vocalizations had moderate influence on the resulting measures of habitat preferences for birds. I suggest that if a detection distance of more than 50 m is used for bird censuses within forested habitats, then comparisons among forest types should be interpreted cautiously unless the researchers demonstrate that biased detection of vocalizations does not affect their conclusions.