Action: Thicken earth wire to reduce incidental bird mortality
A literature review found no evidence that thickening the earth wire had any impact on collision mortality of cranes Grus spp.
Removing earth wires is not always practical, given their protective nature. However, they can be rendered more visible by thickening the wire.
Supporting evidence from individual studies
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