Evaluating the Use of Autonomous Recording Units for Monitoring Yellow Rails

and Other Nocturnal Wet Meadow BirdsAnna M. Sidie-Slettedahl, US Fish and Wildlife Service, South Dakota State

UniversityRex Johnson, US Fish and Wildlife Service

Todd Arnold, University of MinnesotaJane 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

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

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?

6 Minute Surveys

Species 1 2 3 4 5

YERA 72.6% 92.3% 97.8% . .

LCSP 53.2% 80.7% 93.1% 97.8% .

NESP 51.1% 75.9% 88.0% 94.0% 97.0%

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)

Le Conte’s Sparrow

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

• HAPET – US Fish and Wildlife Service

• Agassiz National Wildlife Refuge

• South Dakota State University

Funding: