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

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• It takes several scans (nominally, three) for the DRP’s tracking algorithm to determine<br />

whether a pattern of detections for a target warrants elevation to a confirmed track. This<br />

can add another ~8 seconds to the time uncertainty between the eBirdRad <strong>and</strong> TI-VPR<br />

tracks for a given target.<br />

• The complications of these factors are compounded when a large numbers of birds are<br />

flying <strong>and</strong> being sampled by both systems. With so many targets in the area, it is difficult<br />

to say for certain which targets are the same for both systems.<br />

We decided a more practical approach to confirming targets with thermal imagery was to treat the<br />

data from the two methods as samples (of the population of birds migrating overhead) <strong>and</strong> to<br />

correlate the counts of birds passing through the field of view of the TI-VPR with the counts of<br />

eBirdRad tracks that passed within a 250 m radius of the TI-VPR (see polygons in Figure 6-6<br />

<strong>and</strong> Figure 6-7). On this basis, we performed the following comparisons of the eBirdRad <strong>and</strong><br />

the TI-VPR sampling results:<br />

1. Compared 5-min segments of eBirdRad <strong>and</strong> TI-VPR data, overall (green <strong>and</strong> yellow with<br />

yellow <strong>and</strong> red in Figure 6-8).<br />

2. Compared 5-min segments of TI-VPR birds at the same altitude as the radar beam<br />

(yellow in Figure 6-8).<br />

3. Compared 1-hour sessions for TI bird counts, overall (green <strong>and</strong> yellow with yellow <strong>and</strong><br />

red in Figure 6-8).<br />

4. Compared 1-hour segments for TI birds that are at the same altitude as the radar beam<br />

yellow in Figure 6-8).<br />

Results<br />

The comparisons of bird counts in the TI-VPR <strong>and</strong> those in the sample polygon of the eBirdRad<br />

co-varied significantly. The correlation of overall counts within 5-minute segments from<br />

eBirdRad <strong>and</strong> TI-VPR was highly significant (r = 0.829, v = 94, P < 0.001, Figure 6-10). The<br />

correlation of counts within 5-minute segments from TI-VPR at the same altitude as the radar<br />

beam of eBirdRad was lower but also highly significant (r = 0.639, v = 94, P < 0.001, Figure<br />

6-11). The correlation of overall counts from the TI-VPR <strong>and</strong> eBirdRad for each 1-hour session<br />

was highly significant (r = 0.943, v = 6, P < 0.001, adjusted R 2 = 0.8716; Figure 6-12), <strong>and</strong> the<br />

correlation of counts from the TI-VPR at the same altitude as the radar beam of eBirdRad for<br />

each 1-hour session was also highly significant (r = 0.952, v =6, P

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