Monitoring Raptor Movements with Satellite Telemetry and Avian Radar Systems: An Evaluation for Synchronicity

Abstract

Avian radar technologies have the potential to serve an important role in the quantification of bird movements and determining patterns of bird use in areas where human–wildlife conflicts might occur (e.g., airports, wind energy facilities). Ground-truthing studies are needed to help wildlife managers understand the biological meaning of radar information, as the capabilities and limitations of these technologies are relatively unknown. We conducted a study to evaluate the efficacy of three X-band marine radar sensors for tracking red-tailed hawks (Buteo jamaicensis) on or near the airfield at Chicago’s O’Hare International Airport from September 2010 to May 2014. Specific information regarding red-tailed hawk locations derived from satellite telemetry was used to determine how frequently the three radar sensors provided corresponding tracks of these avian targets (i.e., synchronized monitoring). We examined various factors (e.g., bird altitude and distance to the radar) to determine if they had any influence on the frequency of synchronicity between satellite telemetry locations and radar tracks. We found evidence that as the distance between a hawk and the radars increased, the radars’ ability to detect and track known avian targets decreased. Overall, the frequency of synchronization events for red-tailed hawks was low. Of the 1977 red-tailed hawk locations that should have been visible to the radar sensors, 51 of these bird movements were tracked by at least one of the radar sensors (2.6%). This study provides a new methodology for evaluating the performance of radar systems for tracking birds and determining what factors might influence overall performance.

Field validation of avian radar surveys: effects of differences in species and flock sizes on echoes

“…A more constructive discussion of height can be made if it is considered an elevation angle, since the range of observable heights varies with elevation angle and distance. Previous studies (along with this study) have shown a positive effect on POD at elevation angles below 15 degrees [21,35]. In general, an increase in elevation angle can be assumed to increase the radar cross-section of a bird in ight with its wings spread horizontally.…”

“…However, the high installation cost and strict radio laws and regulations make it inapplicable for widespread use. In contrast, X-band marine radar, the least expensive and least regulated, has been used widely for bird surveys and validated for observation accuracy [18,21,[32][33][34][35]. However, most previous validation studies of radar accuracy have focused on the trajectory output produced by the respective tracking software [21,22,31,35].…”

“…In contrast, X-band marine radar, the least expensive and least regulated, has been used widely for bird surveys and validated for observation accuracy [18,21,[32][33][34][35]. However, most previous validation studies of radar accuracy have focused on the trajectory output produced by the respective tracking software [21,22,31,35]. In general, the initial data obtained from the radar is two-dimensional signal intensity data (hereafter referred to as "raw data").…”

“…In recent studies generating trajectories of ying birds, echo images from marine radar have been used more generally than raw data [18,21,[32][33][34][35][36]. The reason for this may be the di culty in acquiring and handling raw data, as it cannot be acquired by a radar system alone but requires additional equipment, and the volume of raw data is much larger than that of images.…”

Bird Detection and Overall Bird Situational Awareness at Airports

“…By extracting the information of bird behaviors on a macro scale, we are able to obtain the knowledge on bird species, ight altitudes, and different migration patterns (Lin et al, 2022). However, it remains extremely challenging to obtain accurate data on ying birds (Washburn et al, 2022). With the development of information technology, numerous technologies have been applied individually or in combination, such as radar detection (Chen et al, 2009), image recognition (Rai et al, 2022), bioacoustic monitoring (Yang et al, 2022), thermal infrared imaging (Vanhellemont and Ruddick, 2014), etc., to identify and detect ying birds.…”