(IVAR) - Final Report - Strategic Environmental Research and ...

The spring 2007 studies at the Cherry Point (Figure 4-2) and Patuxent River (Figure 4-4), as well
as the fall 2008 study at Elmendorf AFB (Figure 4-6), used eBirdRad avian radars with a 4º
parabolic dish antenna, nominally set at 4º-10º above horizontal. The 2007 study at Whidbey
Island (Figure 4-5) employed an AR-1 avian radar with a 20º array antenna 10 ; the 2008 study at
Whidbey Island used both an AR-1 and an eBirdRad unit.
At each location, “Visual Team” (VT) observation sites were selected around the facility, with
one VT site in each quadrant around, and at different distances from, the radar where possible.
Two-person teams were assigned to a subset of the VT sites during each 2-hour session,
depending upon how many personnel were available for that session. One member of each team
was the visual observer: This person attempted to locate and identify the targets called out by
the Radar Team. The other team member recorded the observation data on a field data form.
Similarly, a two-person “Radar Team” (RT) was assigned to the radar trailer: The radar operator
observed the targets being tracked on the DRP display, while the other team member recorded on
field data sheets information about the tracked targets that was called out by the radar operator.
The Radar and Visual Teams had two-way radios with which they could communicate with one
another.
In additional to the manually recorded VT and RT field data, copies of the digital “plots and
tracks” data files generated by the DRP during each session were saved for later analysis. A 5-
10 minute segment of raw digital data was also saved during each session should questions arise
later regarding the radar’s performance during that session.
Two and occasionally three 2-hour sessions were scheduled each day of a study. The goal was to
have an equal number of morning, mid-day, and evening sessions; the actual time of the sessions
depended on the season and latitude of the study location. During the initial, spring 2007
studies, only “RT-Calls” observations were made. In this scenario, the radar operator would
follow tracks on the DRP display and select one as a good candidate based on a variety of
criteria, including: the duration of the track, the separation from other targets with which it
might be confused, whether the nearest VT likely had an unobstructed view of the target, etc.
The radar operator would then broadcast a Request for Confirmation (RFC) to the VT that was in
the best position to observe the selected target. The broadcast would include the bearing and
distance of the target from the specified VT site. The radar operator would also activate the
image-capture function of the DRP to save a digital picture of the radar display when the RFC
was called.
If the specified or another VT observed a target that matched the position broadcast by the RT,
they would broadcast a confirmation to the RT and record the time, position, quantity, and
species of the observed target. If no team confirmed the specified target, the RT would cancel
that RFC, record it as a non-confirmation, and proceed to the next target.
“VT-Calls” observations were added to the visual confirmation methods in the fall 2008 studies.
In this scenario, if a VT observed a bird they thought was in the radar beam and no other RFC
was in effect at that time, they could broadcast an RFC to the RT, including the estimated bearing
and range from their position to the target. If the RT could match the broadcast description to a
target being tracked by the radar, the RT would broadcast a confirmation and
10
The effective coverage of the 20º antenna is 10º above the horizontal; the other half the beam is below the
horizontal (i.e., into the ground).
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