Passive Acoustic Monitoring of Gunshot Activity in Cooking Lake-Blackfoot Provincial Recreation Area

In the past, monitoring hunting behavior has been limited to self-reported numbers. However, the ability of autonomous recording units to monitor soundscapes may make them suitable for assessing spatio-temporal shooting patterns. Our goal for this project was to find out if it is possible to use acoustic monitoring to track human activity, and if there were differences in seasonal or daily shooting intensities. We hypothesized that shooting intensity would decrease from September to November and from the afternoon till morning due to people being less likely to go shooting in cooler temperatures. A grid of 91 ARU’s were deployed between September 2nd and November 30th, 2018 in Cooking Lake-Blackfoot Provincial Recreation Area. They were set to record continuously between sunrise and sunset with some recording during the night as well. We selected a random subset of 30 minute recordings, visualized them using spectrograms; visual representations of sound with time on the x-axis and frequency on the y-axis, and counted the gunshots in each. We compared differences in gunshot detections between months and different times of day using analysis of variance (ANOVA). There were no statistical differences found in seasonal or daily shooting intensities. One reason for this may be that sample sizes were low, due to the time needed to manually process recordings. We demonstrated that ARU’s can be used to provide us with an accurate way of assessing shooting patterns and therefore, be useful for monitoring other human behaviors such as detecting poachers, or assessing compliance with hunting laws.

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Passive Acoustic Monitoring Reveals Spatio-Temporal Distributions of Antarctic and Pygmy Blue Whales Around Central New Zealand

Frontiers in Marine Science ◽

10.3389/fmars.2020.575257 ◽

2021 ◽

Vol 7 ◽

Author(s):

Victoria E. Warren ◽

Ana Širović ◽

Craig McPherson ◽

Kimberly T. Goetz ◽

Craig A. Radford ◽

...

Keyword(s):

New Zealand ◽

Acoustic Monitoring ◽

Critically Endangered ◽

Blue Whale ◽

Passive Acoustic Monitoring ◽

Animal Populations ◽

Spatio Temporal ◽

Species Specific ◽

Passive Acoustic ◽

Blue Whales

Effective management of wild animal populations relies on an understanding of their spatio-temporal distributions. Passive acoustic monitoring (PAM) is a non-invasive method to investigate the distribution of free-ranging species that reliably produce sound. Critically endangered Antarctic blue whales (Balaenoptera musculus intermedia) (ABWs) co-occur with pygmy blue whales (B. m. brevicauda) (PBWs) around New Zealand. Nationally, both are listed as “data deficient” due to difficulties in access and visual sub-species identification. PAM was used to investigate the distributions of blue whales via sub-species specific song detections in central New Zealand. Propagation models, incorporating ambient noise data, enabled the comparison of detections among recording locations in different marine environments. ABW detections peaked during austral winter and spring, indicating that New Zealand, and the South Taranaki Bight (STB) in particular, is a migratory corridor for ABWs. Some ABW calls were also detected during the breeding season (September and October). PBW calls were highly concentrated in the STB, particularly between March and May, suggesting that an aggregation of PBWs may occur here. Therefore, the STB is of great importance for both sub-species of blue whale. PBW detections were absent from the STB during parts of austral spring, but PBWs were detected at east coast locations during this time. Detection area models were valuable when interpreting and comparing detections among recording locations. The results provide sub-species specific information required for management of critically endangered ABWs and highlight the relative importance of central New Zealand for both sub-species of blue whale.

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