Individual study: A review of the effectiveness of marking power lines and removing earth wires to reduce avian collision mortality
Jenkins A., Smallie J. & Diamond M. (2010) Avian Collisions with Power Lines: A Global Review of Causes and Mitigation with a South African Perspective. Bird Conservation International, 20, 263-278
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Thicken earth wire to reduce incidental bird mortality
A literature review (Jenkins et al. 2010) describes how a paired site study in Colorado, USA (Brown et al. 1987), found that replacing 50% of the earth wire from 3.2 km of 115 kV wire with an earth wire three times thicker than normal had no effect on crane Grus spp. collision mortality compared to the span with a normal thickness earth wire.
Brown, W. M., Drewien, R. C. & Bizeau, E. G. (1987) Mortality of cranes and waterfowl from powerline collisions in the San Luis Valley, Colorado. 128–136 Proceedings of the crane workshop, 1985 Platte River Whooping Crane Maintenance Trust, Grand Island, Nebraska
Remove earth wires to reduce incidental bird mortality
A literature review (Jenkins et al. 2010) described a before-and-after trial (Brown et al. 1987) that found an 80% reduction in collision mortality of sandhill cranes Grus canadensis and whooping cranes G. americana following removal of the earth wire from a 3.2 km span of 116 kV line in Colorado, USA.
Brown, W. M., Drewien, R. C. & Bizeau, E. G. (1987) Mortality of cranes and waterfowl from powerline collisions in the San Luis Valley, Colorado. 128–136 Proceedings of the crane workshop, 1985 Platte River Whooping Crane Maintenance Trust, Grand Island, Nebraska.
Mark power lines to reduce incidental bird mortality
A 2010 literature review (Jenkins et al. 2010) found significant reductions in bird mortality following the marking of power lines in the USA and South Africa. A before-and-after trial over two years in Indiana (Crowder 2000), USA, found significantly reduced mortality with both Bird Flight Diverters (BFDs, 73% fewer fatalities) and larger ‘Swan Flight Diverters’ (50% fewer). The reviewers noted that there was considerable variability in collision rates across all sites. A before-and-after trial over three years in Karoo, South Africa (Anderson 2002) found a 67% reduction in collision mortality following the marking of both earth wires of 10 km of 132 kV line with BFDs (30 cm long) every 10 m. The same study also found that spans marked with BFDs and ‘flappers’ (loosely suspended polycarbon discs) had 52% lower collision mortality than spans marked just with BFDs, and 80% lower collision mortality than the same spans prior to marking. Spans with just flappers had 60% lower mortality than those with BFDs but the results are inconclusive. The reviewers noted a considerable decrease in blue crane Anthropoides paradiseus and Ludwig’s bustard Neotis ludwigii (the main species colliding with the line) populations in the area following marking.
Anderson, M. D. (2002) Large terrestrial bird powerline project. Unpublished report Eskom, Johannesburg.
Crowder, M. R. (2000) Assessment of devices designed to lower the incidence of avian power line strikes. Masters of Science Thesis, Purdue University, East LaFayette, IN. 91p.