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Objective 1: Comparing the Two Survey Methods
Methods:• Isolated all 6 minute recorded standard surveys
(172 in total)• Use “recognizers” to automatically detect and
identify target species calls on recordings
• NO!! Ran into problems: missed detections and too many false positives
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Manual Scan Method
• Resorted to the “Manual Scan” Method• Quickly visually and
aurally scan through recording to detect target species
• Robust design occupancy model in Program MARK
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1 2 3 40
0.2
0.4
0.6
0.8
1
Yellow Rail
Standard Survey
ARU
Survey Repetition
1 2 3 40
0.2
0.4
0.6
0.8
1Le Conte’s Sparrow
Survey Repetition
1 2 3 40
0.2
0.4
0.6
0.8
1Nelson’s Sparrow
Survey Repetition
Probability of Detection
-Each species-Each survey repetition-Each survey method
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Why?
• Most calls not detected on ARU recording, but that were detected during Standard Survey, were too faint or not “strong” enough to be recorded by ARU– Reduced detection by ARUs was likely due to
human observers being able to detect birds at greater distances
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However
• Because ARUs are in the field for longer periods than human observers, there are more cumulative opportunities for detection
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Objective 2: Factors affecting detection
• Looking at temporal and environmental variables that may affect calling and/or detection of these species
• Generalized linear mixed models in R– Presence/absence from 3035 three minute
recordings, from 43 ARU stations– Hourly weather data
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Variables of Interest• Random effect = Survey Site • Fixed effects =
– Year – Julian day– Precipitation (yes or no)– Temperature– Wind speed– Atmospheric pressure– Moonlight– Hours after sunset
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Yellow Rail• Precipitation
No precip. = 0.63 (95%CI = 0.55 and 0.71)Precip. = 0.47 (95%CI = 0.36 and 0.59)
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Le Conte’s Sparrow
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Nelson’s Sparrow• Precipitation
No precip. = 0.22 (95%CI = 0.16 and 0.30)
Precip. = 0.08 (95%CI = 0.03 and 0.16
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Management Implications
• Incorporate these factors into existing survey protocols to improve survey efforts– Standard surveys– Use of ARUs
• Improvement of systematic surveys
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Acknowledgements
• HAPET – US Fish and Wildlife Service
• Agassiz National Wildlife Refuge
• South Dakota State University
Funding: