Cue counting is a method developed for estimating vocally active wildlife density by dividing the density of cues (number of cues per unit area surveyed per unit time) by the average cue rate (ACR) at which individuals vocalize. It has been used successfully to estimate whale density using passive acoustic monitoring, but its efficacy has had limited testing in birds. We tested whether cue counting can be used to infer bird abundance using autonomous recording units and estimated the minimum effort required to obtain a reliable cue rate at individual and population levels. We recorded Dupont's Lark (Chersophilus duponti) vocalizations at 31 sites where traditional field censuses were also performed. We estimated the ACR using three methodologies: directional recordings, recordings from an online database of bird sounds (xeno-canto), and behavioral field studies. The ACRs estimated using directional recordings and behavioral field studies were similar, and bird numbers were over and underestimated by 0.8 and 10%, respectively (74–77% of the sampling sites were well estimated). However, the ACR estimated using xeno-canto recordings was much higher than those estimated using the other two methods, and bird numbers were underestimated by 41%. We also performed a cost-effectiveness assessment of the number of individuals and recording durations needed to optimize the estimation of a reliable ACR. We found that ACR estimates were more efficient if long (25 min) recordings were used when < 4 males were recorded, whereas 5-min recordings were more efficient for ≥ 20 males. We conclude that cue counting can be useful to infer bird density around recorders but requires an accurate measure of the ACR. Further research should evaluate the effectiveness of passive cue counting on a large number of species and under different circumstances.

中文翻译：

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使用无源声波监测评估提示计数以估算鸟类密度：估算可靠提示率的建议

提示计数是通过将提示的密度（每单位时间所调查的单位面积的提示数量）除以个人发声的平均提示速率（ACR）来估算声乐活动性野生动植物密度的一种方法。它已成功用于通过被动声波监测估算鲸鱼密度，但其功效在鸟类中的测试受到限制。我们测试了提示计数是否可以使用自主记录单元来推断鸟的数量，并估算了在个人和种群水平上获得可靠提示率所需的最小工作量。我们在31个地点进行了杜邦的百灵鸟（Chersophilus duponti）发声记录，这些地点还进行了传统的现场普查。我们使用三种方法对ACR进行了估算：定向记录，鸟声音在线数据库（xeno-canto），和行为现场研究。使用定向记录和行为现场研究估计的ACR相似，鸟类数量分别被高估和低估了0.8％和10％（正确估计了74-77％的采样地点）。但是，使用异种Canto记录估算的ACR远​​远高于使用其他两种方法估算的ACR，鸟类数量被低估了41％。我们还对人数进行了成本效益评估，并记录了优化可靠ACR估计所需的持续时间。我们发现，如果录制的男性少于4个，则使用长时间（25分钟）的录制，ACR估计会更有效，而对于≥20个男性，录制5分钟的录制更有效。我们得出结论，提示计数可能有助于推断记录仪周围的鸟类密度，但需要准确测量ACR。进一步的研究应评估在多种情况下和不同情况下被动提示计数的有效性。