Use of autonomous audio recordings for the rapid inventory of birds in the white-sand forests of the Peruvian Amazon

Abstract

White‐sand forests are patchily distributed ecosystems covering just 5% of Amazonia that host many specialist species of birds not found elsewhere, and these forests are threatened due to their small size and human exploitation of sand for construction projects. As a result, many species of birds that are white‐sand specialists are at risk of extinction, and immediate conservation action is paramount for their survival. Our objective was to evaluate current survey methods and determine the relative effect of the size of patches of these forests on the presence or absence of white‐sand specialists. Using point counts and autonomous recorders, we surveyed avian assemblages occupying patches of white‐sand forest in the Peruvian Amazon in April 2018. Overall, we detected 126 species, including 21 white‐sand forest specialists. We detected significantly more species of birds per survey point with autonomous recorders than point counts. We also found a negative relationship between avian species richness and distance from the edge of patches of white‐sand forest, but a significant, positive relationship when only counting white‐sand specialists. Although we detected more species with autonomous recorders, point counts were more effective for detecting canopy‐dwelling passerines. Therefore, we recommend that investigators conducting surveys for rare and patchily distributed species in the tropics use a mixed‐method approach that incorporates both autonomous recorders and visual observation. Finally, our results suggest that conserving large, continuous patches of white‐sand forest may increase the likelihood of survival of species of birds that are white‐sand specialists.

Acoustic monitors and direct observations provide similar but distinct perspectives on bird assemblages in a lowland forest of eastern Ecuador

“… Leach et al (2016) sampled birds in a rainforest in Queensland and found that point counts led to greater estimations of species richness because of additional species detected visually. Similarly, Stevens et al (2019) found that point counts were more useful for canopy passerines in white-sand forests of Amazonia. On the other hand, Alquezar & Machado (2015) found that the two methods gave similar results in cerrado vegetation with visual detections at point counts not contributing additional species.…”

“…Acoustic monitors have proven to be useful for sampling bird species in a variety of habitats, including both temperate ( Celis-Murillo, Deppe & Allen, 2009 ; Depraetere et al, 2011 ; Cook & Hartley, 2018 ) and tropical ( Bueno et al, 2012 ; De Camargo, Roslin & Ovaskainen, 2019 ; Stevens et al, 2019 ) forests. They have been used to provide descriptions of bird species richness, community composition, and change in such communities over space and time ( Towsey et al, 2014 ; De Camargo, Roslin & Ovaskainen, 2019 ; Stevens et al, 2019 ). Recordings from acoustic monitors also have been used to develop acoustic indices that provide information on diversity, without identification of individual species ( Depraetere et al, 2011 ; Towsey et al, 2014 ; Aide et al, 2017 ).…”

Simultaneous passive acoustic monitoring uncovers evidence of potentially overlooked temporal variation in an Amazonian bird community

“…2014). Stevens et al . (2019) used ARUs at heights of 2-5m and documented decreased detection rates of canopy-dwelling mixed flock species relative to point counts, but found no such effects in habitats with shorter, smaller trees, supporting the idea that the distance between recorder and canopy height meaningfully influences detection rates of canopy species.…”

Monitoring canopy bird activity in disturbed landscapes with automatic recorders: A case study in the tropics

“…The system can be therefore considered as simple, efficient and accessible to non-experts. Several studies have shown that similar PAM systems can be as informative as point count sampling technique traditionally used in conservation programs (Haselmayer and Quinn, 2012;Shonfield and Bayne, 2017;Stevens et al, 2019).…”