Using Theoretical Flight Speeds to Discriminate Birds from Insects in Radar Studies

Cabrera‐Cruz, Sergio A.; Mabee, Todd J.; Villegas-Patraca, Rafael

doi:10.1525/cond.2013.110181

Cited by 15 publications

(13 citation statements)

References 30 publications

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“…I kept only tracks with airspeeds greater or equal to 7m/s. Using this airspeed as a cut-off point may likely keep some faster flying insects and eliminate some slower migration birds but will assure that the majority of tracks are comprised of bird migrants (Cabrera-Cruz et al 2013).…”

Section: Separating Insect Tracks From Bird Tracksmentioning

confidence: 99%

Does the Lake Huron Shoreline Influence Distributions, Altitudes, and Flight Directions of Nocturnally Migrating Birds?

Villeneuve¹,

Thomas²

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Section: Separating Insect Tracks From Bird Tracksmentioning

confidence: 99%

Does the Lake Huron Shoreline Influence Distributions, Altitudes, and Flight Directions of Nocturnally Migrating Birds?

Villeneuve¹,

Thomas²

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“…Typically, differentiation between bird and insect targets in radar data is carried out by calculating respective airspeeds (Schmaljohann et al 2008, Cabrera-Cruz et al 2013, however, at wind energy sites wind speeds may be sufficiently high to cause the passive movement of insects to overlap flight speeds associated with birds. I have demonstrated that a high proportion of insect contamination can be filtered based on the target characteristics measured by radR.…”

Section: Discussionmentioning

confidence: 99%

“…Otter, unpublished data). In most cases these non-vertebrate aerial targets were moving at a lower speed relative to other targets on the radar monitor and were often moving in a different trajectory, mirroring passive movement with wind currents characteristic of insects (Cabrera-Cruz et al 2013 ). These targets were recorded by the radar as oblong-shaped, low-intensity targets and were detected primarily at closer ranges ( e.g., <750 m).…”

Section: 5 Filtering/or Non-vertebrate Aerial Targetsmentioning

confidence: 99%

“…The capture and processing of these digital radar data also allowed for the collection of detailed information on timing of occurrence, target location and size from which variables such as speed, trajectory and bearing can be determined. Size estimates can be used to discriminate avian targets from non-avian targets, such as insects or other radar clutter that may be present (Larkin 1991, Cabrera-Cruz et al 2013 ). In addition, size estimates may also be used to differentiate targets into different avian taxa.…”

Section: Bird Movements and Collision R Iskmentioning

confidence: 99%

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Movement patterns of noctural avian migrants at a wind energy project in northeast British Columbia

d'Entremont¹

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In North America, the migration corridors of passerine birds between breeding and non-breeding grounds are relatively well documented, and along these corridors passerines generally move in a broad-front fashion interspersed with stopover periods in which to rest and replenish fuel stores. Understanding movement patterns at individual locations along these routes is required to identify whether anthropogenic developments, such as wind energy installations, can lead to disruption or collision risk during migrations. Wind energy installations are becoming more numerous in the corridors along migration routes as they use the same wind resources exploited by migratory birds. Documenting collision risk to nocturnal migrants, particularly passerines, through the collection of accurate data on the movement patterns and flight altitudes at wind energy sites during both pre-operational and operational phases is needed to correctly assess the level of risk to these birds.Using standard marine radar units equipped with an inexpensive digital interface system, I automated the detection and extraction of radar echo signatures or target information for nocturnal migrants (Chapter 2) at a wind energy site in northeast British Columbia. Using the open source software program radR, I identified optimal values for input criteria to automatically detect and track these migrants with high accuracy from the digital radar data, when compared to known, manually-tracked targets (R 2 = 0.94). The program was also effective in reducing the amount of insects that were detected and tracked.Use of the auto-tracking software also increased the number of detected targets by over 500~0 compared to the real-time collection of radar data.Using radR, I analyzed the micro-scale movements of nocturnal migrants during the pre-operational and operational periods of the wind energy project (Chapter 3). Despite variations in wind conditions between seasons, migrants showed consistent directionality and general trends of broad-front migration at altitudes typically above the height of wind turbines. In the spring, migrants were predominantly utilizing favourable tailwinds, but when wind conditions changed, migratory direction at the micro-scale level appeared to remain constant. In the fall, migrants were rarely moving with favourable winds and were predominantly facing headwind or crosswind conditions. Regardless, at the micro-scale level nocturnal migrants were not significantly adjusting their movements around the wind energy facility during the operational period and their typical migratory behaviour was not placing them in potential collision risk situations. The data collection and results of my work has also contributed to additional papers.

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“…Research applications include: estimating movements and numbers of threatened species (e.g. marbled murrelets; Burger, 2001); identifying dense migratory areas (Desholm et al 2014); studying effects of weather on migratory behavior (Kahlert et al 2012) and passage rates (Thomas et al 2011); assessing theoretical flight speeds (Cabrera-Cruz et al 2013); and understanding the influence of topography on migration (Williams et al 2001).…”

Section: Figurementioning

confidence: 99%

A Simulation Model of the Detection Patterns of Birds Using Marine Radars

Souliere¹

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Many bird radar studies provide estimates of the number of birds flying past a given area, but very few of these actually estimate detectability. One of the challenges in radar ornithology is estimating the probability of detection of flying targets with altitude and distance. I estimated the detection patterns associated with three marine radars by using a combination of field trials and simulation modelling, and estimated the probabilities of correctly and incorrectly detecting birds in relation to altitude. Field trials were conducted between December 18 th 2015 and January 08 th 2016 in Russell, Ontario, using radars to detect an aluminum sphere suspended below weather balloons. The results indicate considerable variation in power among radar units. The nominal beam width (+/-3dB) was 4 degrees and effective beam width as measured by the blip size was 7 degrees. Models of beam shape and return echo strength from these trials were implemented into a simulation model. The results indicate detectability varies with altitude, with few birds detected in the lower altitude bands relative to the highest. Many simulated birds were classified as two different birds when crossing the beam twice. The algorithm to remove background clutter was only partially successful, as there were many false detections, especially in the lowest altitude bands near the radar. Future bird radar studies should include data on detection probabilities, using the approaches described here or other comparable approaches.iii ACKNOWLEDGMENTS I would like to express my sincere gratitude to my supervisor Dr. Charles M. Francis for his guidance and unwavering support during this endeavor, for his patience in trying times and for sharing his wealth of knowledge.A special thanks goes to my committee members for their insightful comments and generous feedback, especially so given the topic of my thesis. I thank Dr. Lenore Fahrig, Dr.My sincere appreciation goes to Dr. Philip D. Taylor and John M. Brzustowski for their invaluable advice in helping me structure the framework of my thesis and offering practical solutions to radar and simulation technicalities.

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Using Theoretical Flight Speeds to Discriminate Birds from Insects in Radar Studies

Cited by 15 publications

References 30 publications

Does the Lake Huron Shoreline Influence Distributions, Altitudes, and Flight Directions of Nocturnally Migrating Birds?

Does the Lake Huron Shoreline Influence Distributions, Altitudes, and Flight Directions of Nocturnally Migrating Birds?

Movement patterns of noctural avian migrants at a wind energy project in northeast British Columbia

A Simulation Model of the Detection Patterns of Birds Using Marine Radars

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