Assessing Collision Risk in White-Tailed Eagles Using Laser Range-Finder Technology

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