Evaluation of autonomous recording unit performance in detecting Black-billed Cuckoos

Author

Jenna L. Asnault, University of Montana, MissoulaFollow

Graduation Year

2023

Graduation Month

May

Document Type

Thesis

Degree Name

Bachelor of Science

School or Department

Wildlife Biology

Major

Wildlife Biology

Faculty Mentor Department

Wildlife Biology

Faculty Mentor

Erim Gomez

Faculty Reader(s)

Creagh Breuner, Erick Green, Anna Noson

Keywords

ARU, cuckoo, detection, performance, distance

Subject Categories

Biodiversity | Other Animal Sciences | Research Methods in Life Sciences | Zoology

Abstract

Black-billed Cuckoos (Coccyzus erythropthalmus) are classified as a species of concern in Montana and have declined due to habitat loss and fragmentation. Cuckoos are challenging to study, as they do not move or call frequently in the presence of people. This makes researching and managing these birds difficult. Autonomous acoustic survey methods offer the potential to be more effective than traditional avian survey methods. Autonomous recording units (ARUs) are small, programmable, relatively inexpensive acoustic detectors, and have been used in several other studies. Cuckoos, however, nest and perch in dense riparian vegetation, potentially limiting the detection capabilities of ARUs. I investigated the detection distance of ARUs and how that changes in the presence of varying levels of vegetation density. I set up thirteen 200-meter transects in locations in western Montana. Each site had different levels of vegetation density, from open landscape to dense foliage. We mounted an ARU to a 2 m PVC pipe at one end of the transect, then played Black-billed Cuckoo calls from a speaker at 50 m intervals. I then analyzed how well the ARU detected the calls at each distance interval and examined how that changed with increased vegetation density. Detection capability decreased as distance increased, then detection decreased further as vegetation increased. Detection also varied depending on the various call types used by cuckoos. These results suggest an ARU can detect a coo call, the most common call type, within 47 m, a kowlp call within 125 m, and a long call within 131 m at a detectability score of 3 in areas with no vegetation. In moderate vegetation, the ARU could detect a coo call within 83 m, a kowlp call within 89 m, and a long call within 92 m. In dense vegetation, the ARU could detect a coo call at about 45 m, a kowlp call at about 31 m, and a long call at about 35 m. These results demonstrate the detection capabilities of ARUs across distances and with varying vegetation densities. I recommend that researchers employ a pilot study on ARUs to evaluate the efficacy of call detection across different distances and environments for their target species.

GLI Capstone Project

no

Recommended Citation

Asnault, Jenna L., "Evaluation of autonomous recording unit performance in detecting Black-billed Cuckoos" (2023). Undergraduate Theses, Professional Papers, and Capstone Artifacts. 536.
https://scholarworks.umt.edu/utpp/536