Ramesh Vijay, Sundar Pavithra, Srivathsa Meghana, Symes Laurel
K Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA.
Project Dhvani, Bangalore, India.
Philos Trans R Soc Lond B Biol Sci. 2025 Jun 12;380(1928):20240054. doi: 10.1098/rstb.2024.0054.
Bird species vary widely in their diurnal vocalization patterns, and the drivers of this variation are not well understood. Using passive acoustic monitoring, we examined species-specific vocal activity patterns at dawn and dusk for a tropical bird community in the Western Ghats biodiversity hotspot in India. We tested whether environmental factors (e.g. signal transmission conditions, ambient light, and resource availability) and social factors (e.g. territoriality) best-explained patterns of diurnal variation in vocal activity. Overall, we found that species-specific vocal activity was significantly higher at dawn ( < 0.05). Phylogenetic generalized least squares regressions revealed that territoriality and diet both predicted stronger dawn-biased activity. Specifically, highly territorial birds (standardized effect size (SES) = 1.20, lower donfidence interval (LCI)= 0.24, upper confidence interval (UCI) = 2.16, = 0.01) and omnivores (SES = 0.82, LCI = -0.04, UCI = 1.68, = 0.06) had higher levels of vocal activity at dawn. Surprisingly, we failed to find any evidence in support of environmental factors in explaining dawn-biased vocal activity. Our multi-taxon approach allowed us to assess the vocal activity patterns for an entire tropical bird community. Future research must incorporate additional geographic locations and combine visual and aural observations to better understand the drivers of diurnal variation in vocal activity.This article is part of the theme issue 'Acoustic monitoring for tropical ecology and conservation'.
鸟类物种在其昼夜发声模式上差异很大，而这种差异的驱动因素尚未得到很好的理解。我们通过被动声学监测，研究了印度西高止山脉生物多样性热点地区一个热带鸟类群落在黎明和黄昏时特定物种的发声活动模式。我们测试了环境因素（如信号传输条件、环境光和资源可用性）和社会因素（如领地性）是否能最好地解释发声活动的昼夜变化模式。总体而言，我们发现特定物种的发声活动在黎明时显著更高（<0.05）。系统发育广义最小二乘回归显示，领地性和饮食都预测了更强的黎明偏向性活动。具体来说，高度领地性的鸟类（标准化效应大小（SES）=1.20，下限置信区间（LCI）=0.24，上限置信区间（UCI）=2.16，=0.01）和杂食性鸟类（SES = 0.82，LCI = -0.04，UCI = 1.68，=0.06）在黎明时的发声活动水平更高。令人惊讶的是，我们没有找到任何证据支持环境因素能解释黎明偏向性发声活动。我们的多分类群方法使我们能够评估整个热带鸟类群落的发声活动模式。未来的研究必须纳入更多地理位置，并结合视觉和听觉观察，以更好地理解发声活动昼夜变化的驱动因素。本文是主题为“热带生态与保护的声学监测”的一部分。
