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Evaluating the Use of Autonomous Recording Units for Monitoring Yellow Rails and Other Nocturnal Wet Meadow Birds. Anna M. Sidie-Slettedahl , US Fish and Wildlife Service, South Dakota State University Rex Johnson, US Fish and Wildlife Service Todd Arnold, University of Minnesota
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Evaluating the Use of Autonomous Recording Units for Monitoring Yellow Rails and Other Nocturnal Wet Meadow Birds • Anna M. Sidie-Slettedahl, US Fish and Wildlife Service, South Dakota State University • Rex Johnson, US Fish and Wildlife Service • Todd Arnold, University of Minnesota • Jane Austin, USGS Northern Prairie Wildlife Research Center • Joshua Stafford, USGS South Dakota Cooperative Fish & Wildlife Research Unit • KC Jensen, South Dakota State University
Introduction • Limited knowledge of these species: • Yellow Rail • Nelson’s Sparrow • Le Conte’s Sparrow
Conservation • Loss and degradation of wetlands due to human activity • All three = Species of Greatest Conservation Need in MN • Yellow Rail = species of high concern • North American Waterbird Conservation Plan • Northern Prairie and Parkland Waterbird Conservation Plan
Systematic surveys are needed • USFWS & USGS: Standardized North American Marsh Bird Monitoring Protocols (Conway 2009) • However… • Tendencies to call at night = often times missed by surveys • Also… • Secretive habits • Cryptic coloration • Difficult to access habitat Dr. Jim Petranka
Autonomous Recording Units (ARUs) • Good candidates for surveying with ARUs that can be analyzed in a laboratory • Benefits: • Minimize observer biases • Permanent records of surveys • 24 hr/day data collection • Limited numbers of expert field observers • Disadvantages: • No visual detections • Estimating distances and numbers of birds? • Time spent going through recordings
Song Scope Bioacoustics Recognition Software • Ideally, you build “recognizers” to scan recordings
Main Objectives • Compare the detection probabilities of these three species using ARUs versus the standard marsh bird monitoring protocol. • Use ARU recordings to determine temporal (daily and seasonal) changes in species calling and environmental factors affecting detection, in order to improve survey efforts
Field Methods • 16 survey routes, 10 stations • 22 ARUs (per season; 1-4 ARUs/route) • SM1 Song Meter, Wildlife Acoustics • 10 min every 15 min, from 20:00 until 08:00
Field Methods • Standard Marsh Bird Protocol • Call-broadcast surveys--Yellow Rail call only • Start 1 hour after sunset • May-June = survey season • 4 times/season
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
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
Probability of Detection -Each species -Each survey repetition -Each survey method
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
How many 6 minute ARU recordings to be at least 95% sure of detection?
However • Because ARUs are in the field for longer periods than human observers, there are more cumulative opportunities for detection
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
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
Yellow Rail • Precipitation No precip. = 0.63(95%CI = 0.55 and 0.71) Precip. = 0.47(95%CI = 0.36 and 0.59)
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
Management Implications • Incorporate these factors into existing survey protocols to improve survey efforts • Standard surveys • Use of ARUs • Improvement of systematic surveys
Acknowledgements Funding: • HAPET – US Fish and Wildlife Service • Agassiz National Wildlife Refuge • South Dakota State University