Vocalization and acoustic activity pattern of the Bolivian Bamboo Rat (<i>Dactylomys boliviensis</i>) from southwestern Amazon through passive acoustic monitoring

Abstract The Bolivian Bamboo Rat (Dactylomys boliviensis)—a large arboreal rodent found in the western Amazon—is known for its distinctive vocalizations and frequent presence in bamboo-dominated forests. While some aspects of its vocalizations have been briefly described, variability in its vocal patterns and times of acoustic activity remain largely unknown. Using passive acoustic monitoring (PAM), we investigated and characterized vocalizations in a southwestern region of the Amazon, analyzing acoustic activity patterns and the influence of bamboo forest coverage and moon illumination. The study was conducted at 165 sites in the Madre de Dios region of Peru during the dry seasons of 2017 and 2018, recording 63 vocalizations over 20,790 recorder days. We found no significant variability in vocalization characteristics or structure in this region, suggesting that previous reports might be biased due to the influence of the observer on the activity of animals and the lack of temporal and spatial independence of data. The vocalization of this species followed a distinct pattern of sequential pulses, averaged 28.76 pulses, lasted 31.27 s, and did not show harmonics below 400 Hz. The acoustic activity pattern comprised 2 peaks during the night: 1 between 1 to 2 h and another between 3 and 5 h after sunset. The extent of bamboo-dominated forest cover and moon illumination did not seem to affect the vocalization parameters or nocturnal acoustic activity of this species. Based on our findings, we highlight the benefits of PAM and advocate for its use in future studies on vocal and elusive mammals. Finally, we suggest that future studies should focus on how factors such as the vegetation type and habitat heterogeneity might influence vocal variation, acoustic activity, and occurrence of this species.