Using extended‐duration audio recordings to survey avian species

Abstract

Point‐count surveys are widely used to infer avian presence and estimate species richness. Advancements in bioacoustic technology enable automated surveys that can supplement human‐based point‐count surveys with expanded temporal and spatial coverage. We surveyed birds in 13 Sierra Nevada and Cascade Range (CA, USA) montane meadows from May to August 2006 using 8 point‐count surveys and automated audio recorders (ARU) to compare species richness between the 2 methods and evaluate the use of ARUs as a monitoring tool. We analyzed species richness using 30 minutes of ARU data per point and 2 point‐count surveys. Automated audio‐recorder data revealed 14 species per meadow (56 species total) while point counts detected 16 species per meadow (67 species total). Automated audio recorders provided >1,100 additional hours of data with personnel effort similar to 2 point‐count surveys. An asymptote in species richness was reached for every meadow using ARU data and 8 of 13 meadows using 2 point‐count surveys. We detected 81 species during all 8 point‐count surveys. We used SonoBird (DNDesign, Arcata, CA) software to search for 24 species detected by point‐count surveys but not in the manually sampled subset of audio files. We detected 22 additional species, bringing the total audio‐file species detections to 85, 4 more than detected by 8 point‐count surveys. We conclude that audio recordings and analysis provide an alternative to avian point‐count surveys or as a supplement to increase their accuracy, particularly over larger temporal and spatial scales, or for species with low detectability. © 2012 The Wildlife Society.

Experimentally derived detection distances from audio recordings and human observers enable integrated analysis of point count data

“…First, some detections in HPC may be only visual, particularly of rare or of quiet species that are unavailable to ARUs, or rarely vocalizing species that are unlikely to be detected in short-duration recordings (Haselmayer andQuinn 2000, Hutto andStutzman 2009). Second, because ARUs provide a permanent record for review, there may be a negative bias associated with species detection in HPC relative to ARU recordings because people listening to ARU data can relisten to a sound (Tegeler et al 2012). This bias could be modeled as observer effects.…”

Autonomous recording units in avian ecological research: current use and future applications

“…Several studies also suggested that using both methods in combination could be more effective than either method alone (Celis-Murillo et al 2009, 2012, Tegeler et al 2012, Digby et al 2013, Alquezar and Machado 2015). Only one study in which humans performed better than ARUs reported that ARUs were not cost effective compared to point counts, but acknowledged the utility of a permanent record and recommended the use of portable recorders when conducting point counts (Hutto and Stutzman 2009).…”

“…ARUs can be set up or taken down in a matter of minutes and, although they require a minimum of two visits by field personnel, they require less field time in total compared with point counts in some cases (e.g., Holmes et al 2014). ARUs can be programmed to record for a similar duration as point counts (e.g., 3-10 min), but can make several recordings per day and multiple surveys can be done over several days or months (e.g., Goyette et al 2011, Tegeler et al 2012. The increased temporal effort makes ARUs a useful tool for studying rare or elusive species that vocalize infrequently , Cerqueira and Aide 2016.…”

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

“…Furthermore, the presence of a surveyor may affect detection, especially for cryptic species, species found at low densities, and species sensitive to human presence (Tegler et al. ). The combination of these factors and the density of vegetation in tropical rainforests highlights the need for alternative survey techniques.…”