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Hot stuff in the bushes: thermal imagers and the detection of fossorial burrows in vegetated sites
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  • Tarnya Cox,
  • Robert Matthews,
  • Grant Halverson,
  • Stephen Morris
Tarnya Cox
NSW Department Primary Industries
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Robert Matthews
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Grant Halverson
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Stephen Morris
New South Wales Department of Primary Industries
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Abstract

1. 1. Thermal imaging technology is a developing field in wildlife management. Most thermal imaging work in wildlife science has been limited to larger ungulates and surface-dwelling mammals. Little work has been undertaken on the use of thermal imagers to detect fossorial animals and/or their burrows. Survey methods such as white-light spotlighting can fail to detect the presence of burrows (and therefore the animals within), particularly in areas where vegetation obscures burrows. Thermal imagers offer opportunity to detect the radiant heat from these burrows, and therefore the presence of the animal, particularly in vegetated areas. Thermal imaging technology has become increasingly available through the provision of smaller, more cost-effective units. Their integration with drone technology provides opportunities for researchers and land managers to utilise this technology in their research/management practices. 2. We investigated the ability of both consumer (AUD$65,000) mounted on drones to detect rabbit burrows (warrens) and entrances in the landscape as compared to visual assessment. 3. Both types of imager and visual inspection detected active rabbit warrens when vegetation was scarce. The presence of vegetation was a significant factor in detecting entrances (P<0.001, α=0.05). The consumer imager did not detect as many warren entrances as either the professional imager or visual inspection (P=0.009, α=0.05). Active warren entrances obscured by vegetation could not be accurately identified on exported imagery from the consumer imager and several false-positive detections occurred when reviewing this footage. 4. We suggest that the exportable Hz rate was the key factor in image quality and subsequent false positive detections. This feature should be considered when selecting imagers. Thermal imagers are a useful additional tool to aid in identification of entrances for active warrens and professional imagers detected more warrens and entrances than either consumer imagers or visual inspection.

Peer review status:UNDER REVIEW

15 Sep 2020Submitted to Ecology and Evolution
16 Sep 2020Assigned to Editor
16 Sep 2020Submission Checks Completed
24 Sep 2020Reviewer(s) Assigned