Improving passive acoustic monitoring methods for anuran amphibians in northern Alberta, Canada

• Author / Creator

  Cameron, Jillian

• The global decline of amphibian populations has been documented since the 1960’s. As such, amphibian monitoring programs are becoming increasingly important, in order to inform conservation strategies. Passive acoustic monitoring, i.e. recording the vocalizations produced by animals to detect them, is an increasingly common tool for anuran amphibians, allowing efficient collection of large amounts of data. I used autonomous recording units in wetlands across northern Alberta, Canada, to survey anurans during the breeding season. The overall goal of this thesis is to improve acoustic monitoring programs for anurans.
  First, I evaluated a method for visually scanning spectrograms as a more efficient means of processing recordings than the current standard of human listening. I assessed the effectiveness of visual scanning relative to human listening through generating occupancy models for four species of anurans based on data collected via the two techniques. Secondly, I evaluated patterns of calling behaviour in response to different light conditions at night, specifically the lunar phase and presence of light pollution, to help identify environmental conditions more favorable for detecting anurans through recordings. I also conducted a literature review to highlight the current knowledge of the effects of light on anuran breeding behaviour.
  I determined that visual scanning is more efficient for processing acoustic data than human listening. Listening to this set of recordings took 6.5 times longer than analysis via visual scanning. Occupancy estimates from models based on visual scanning data were comparable to those using listening data for all four study species. The development of a combination occupancy model, based on data from both analytical techniques, showed that including listening data from a sub-set of recording stations, in addition to data from visual scanning, improved model estimates. Visual scanning can be used to improve efficiency of acoustic processing and could be applied to non-amphibian species with similar vocalization characteristics, such as a high call rate, or are distinctive because of unique call frequencies or diel activity patterns. My second set of results suggest that lunar phase and light pollution did not have a strong effect on calling behaviour of boreal chorus frog or wood frog. In conjunction with the literature review, my results suggest that light levels could play a role in anuran behaviour but calling behaviour may not be the ideal metric for evaluating their effects. My research can help inform monitoring and conservation plans through improved methodology and a greater understanding of anuran behaviour.

• Subjects / Keywords

  • amphibian
  • bioacoustic
  • light
  • anuran
  • monitoring
  • occupancy

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-a9ya-ws46

• License

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