Evaluating survey methods for the Yellow Rail: comparison of
human surveys and autonomous recording units Kiel Drake and Danica
Hogan
Slide 3
Background Status of the Yellow Rail Federally listed as spp.
of special concern in Canada Elusive species that is predominantly
nocturnal Occupies habitats that are not covered by roadside
surveys (i.e. not well-sampled by existing monitoring programs)
Knowledge of breeding distribution, occurrence and abundance is
incomplete
Slide 4
Surveys for Yellow Rails Human Surveys YERA occur in places
that can be difficult to access Survey efforts need to be nocturnal
Intensive survey protocol that employs call broadcast sampling and
2 visits to each station Observers count individual calling males
using auditory cues and determine (i.e., guess) distances to
individuals Autonomous Recording Units ARUs: programmable, digital
recorder that can enhance sampling opportunities Studies show that
listeners of recordings detect similar to greater numbers of
spp.
Slide 5
Study Objectives 1.Compare estimates of occupancy, abundance,
and detection probabilities that emanate from human surveys and ARU
recordings. 2.Gain a better understanding of seasonal and diurnal
variation in calling behaviour. ?
Slide 6
Study Site: near Foam Lake, SK
Slide 7
Methods: sampling Human Surveys Conducted point-count surveys
24 May-11 July between 22:00-03:00 hrs. (2011-2013) 2-5 human
surveys per station. Standardized marsh bird monitoring protocol:
10-min survey, call-broadcast sampling, and minute-by- minute
tracking of individuals. Autonomous Recording Units Programed to
record for 5-min at the beginning of each hour between 18:00-09:00
hrs. ARUs remained at each station for several days during
deployment Recordings were processed in a lab setting
Slide 8
Methods: lab-based listening Listeners used noise cancelling
headphones, a spectrogram, and were permitted to pause/rewind
during processing Survey results entered directly into a database
YERA were counted using both aural cues and visual cues from the
spectrogram
Study Objectives 1.Compare estimates of occupancy, abundance,
and detection probabilities that emanate from human surveys and
processing of recordings. 2.Gain a better understanding of seasonal
and diurnal variaiton in calling behaviour. ?
Slide 12
Objective 1: analysis N-mixture models in the R package
unmarked Fits hierarchical models of wildlife occurrence and
abundance Requires a repeated-measures type of sampling design;
spatial sampling is an explicit component of the problem.
Accommodates counts of individuals that may not be uniquely
recognized Unmarked provides a unified framework for analysis
recognizing that observations are generated by a combination of (1)
a state process determining abundance/occupancy and (2) a detection
process that yields observations conditional on the state
process.
Slide 13
Objective #1 Results: Human v. ARUs (N)
Slide 14
Slide 15
Objective #1 Results: Human v. ARUs (p)
Slide 16
Objective #1 Results: Human v. ARUs ( )
Slide 17
Objective #1 Results: Human v. ARUs ( p )
Slide 18
Discussion
Slide 19
ARUs have a smaller overall sampling radius due to internal
microphone noise. ARUs are probably more consistent (among units)
at hearing than people are at hearing and determining distance to
calling birds. What is the area being surveyed by ARUs when the
target species is Yellow Rail?
Slide 20
Experiment: ARU detection of YERA calling
Slide 21
Preliminary Results: ARUs & calling YERA
Slide 22
Study Objectives 1.Compare estimates of occupancy, abundance,
and detection probabilities that emanate from human surveys and
processing of recordings. 2.Gain a better understanding of seasonal
and diurnal variation in calling behaviour. ?
Slide 23
Objective #2 Results: diurnal variation ARU data 2011-2013 n
6,100
Slide 24
Objective #2 Results: seasonal variation ARU data 2011-2013
22:00-03:00 hrs n 3,081
Slide 25
Study Objectives 1.Compare estimates of occupancy, abundance,
and detection probabilities that emanate from human surveys and
processing of recordings. ARUs provide more precise estimates of
abundance and are likely more consistent in the area that is
surveyed. 2. Gain a better understanding of seasonal and diurnal
phenology of calling behaviour. Highest rate of detection occurred
between 23:00-0300hrs and approximately May 23- June 30.
Slide 26
Partners & Sponsors Environment Canada/Canadian Wildlife
Service Saskatchewan Fish &Wildlife Development Fund
Saskatchewan Water Security Agency Service Canada HRDC Science
Horizons Wildlife Habitat Canada
