Estimating bird detection distances in sound recordings for standardising detection ranges and distance sampling

1) Autonomous sound recorders are increasingly used to survey birds, and other wildlife taxa. Species richness estimates from sound recordings are usually compared with estimates obtained from established methods like point counts, but so far the comparisons were biased: Detection ranges usually differ between the survey methods, and bird detection distance data are needed for standardizing data from sound recordings. 2) We devised and tested a method for estimating bird detection distances from sound recordings, using a reference recording of test sounds at different frequencies, emitted from known distances. We used our method to estimate bird detection distances in sound recordings from tropical forest sites where point counts were also used. We derived bird abundance and richness measures and compared them between point counts and sound recordings using unlimited radius and fixed radius counts, as well as distance sampling modelling. 3) First we show that it is possible to accuratel...1) 自主声学记录仪（Autonomous Sound Recorders）正愈发广泛地应用于鸟类及其他野生动物类群的调查工作。基于声学录音的物种丰富度估算结果，通常会与样点计数（point counts）这类成熟调查方法得到的估算值进行对比，但截至目前此类对比均存在系统性偏差：不同调查方法的有效探测范围往往存在差异，若要标准化声学录音的调查数据，需获取鸟类探测距离的相关参数。2) 我们开发并验证了一种可从声学录音中估算鸟类探测距离的方法，该方法依托在已知距离处播放的不同频率测试声音的参考录音。我们将该方法应用于同时开展了样点计数的热带森林样地，以此估算声学录音中的鸟类探测距离。我们推导得到鸟类多度与物种丰富度指标，并分别采用不限半径计数、固定半径计数以及距离抽样建模（distance sampling modelling）的分析手段，对比了样点计数与声学录音的相关调查结果。3) 首先我们证实，能够精准地……