Assessing collision risk in white-tailed eagles Haliaeetus albicilla using laser range-finder technology Simon HULKA 1, David MCLEOD 1, Jesper LARSEN 2
Natural Research (Projects) Ltd 2 Vattenfall Vindkraft A/S 1
Eagles of Palearctic: study and conservation 20-23 September 2013, Elabuga, Russia.
Unaided visual method
Problems associated with unaided visual method Estimates relate to ground surface Between-site differences Between-observer differences above risk at risk below risk
Laser range-finder monitoring
Range up to ca. 8km for a 2.3 x 2.3m target Location data accurate to Âą 5m Height data to Âą 3 m at 1000m
Images: ww.vectronix.com
Seconds at risk height per hour of observation 80m turbine hub
123m turbine hub
Collision risk mortality estimates 80m turbine hub Parameter Flight risk volume (Vw) Rotor radius Combined rotor swept volume (Vr) Vr * (max rotor depth (d) + bird length (l)) Bird occupancy (n) Bird occupancy of rotor swept vol (b) Bird transit time (t) Number of transits through rotors Estimated collisions with no avoidance Estimated number of collisions allowing for avoidance Collision risk estimate allowing for avoidance equivalent to one bird every
123m turbine hub Value 930000 2162.25 101894 285302 0.07 82.33 0.22 382.24 32.56
Unit m^3 m^2 m^3 m^3 hrs / yr bird-secs secs per year per year
0.65
per year
1.5
years
Parameter Flight risk volume (Vw) Rotor radius Combined rotor swept volume (Vr) Vr * (max rotor depth (d) + bird length (l)) Bird occupancy (n) Bird occupancy of rotor swept vol (b) Bird transit time (t) Number of transits through rotors Estimated collisions with no avoidance Estimated number of collisions allowing for avoidance Collision risk estimate allowing for avoidance equivalent to one bird every
Value Unit 1130000 3192.25 150431 421207 0.04 51.05 0.22 237.00 20.65
m^3 m^2 m^3 m^3 hrs / yr bird-secs secs per year per year
0.41
per year
2.4
years
Benefits Flights with accurate data points Field data entry reduced Between-observer bias reduced Portability
Some limitations Cost Non-continuous height and location data Distance between rangefinder fixes varies
Future improvements Between-rangefinder height estimates
May et. al. 2011
Brownian Bridge movement model
May, R., Nygürd, T., Dahl, E. L. & Bevanger, K. 2013. Habitat utilization in white-tailed eagles Haliaeetus albicilla and the displacement impact of the Smøla wind-power plant. Wildlife Society Bulletin, 37, 75-83.
Integrating with GPS / GIS
http://cintos.org/LiDAR_images/index.html
Some alternatives Radar
http://www.detect-inc.com/avian.html
GPS/satellite telemetry
Summar y Laser range-finder method provides more reliable , accurate estimates of eagle flight behaviour. Improved flight data improves our ability to assess the likelihood of eagles colliding with wind turbines and powerlines prior to there construction. Improved assessments better inform decision-making about the location and design of these developments. Portability of the technology make it particularly suited to; • remote or difficult to access areas where use of radar is impractical; • studies of non-breeding and migrating eagle aggregations where tagging is impractical.
Acknowledgeme nts Project Coordinators Mike Madders Jesper Larsen Mike McGrady Simon Hulka
Collision Risk Model Analysis Dave Mcleod
Fieldwork Jan Pettersson