2008

Waterfowl and breeding bird surveys were conducted at Abberton Reservoir Special Protection Area between 2004 and 2006 as part of a study related to an environmental impact assessment. A secondary finding of these surveys revealed a significant level of mortality in spring for mute swans Cygnus olor, and other waterbirds that were colliding with nearby overhead power lines. In the spring of 2004, nine mute swans were killed through collision with the 132Kv power lines, while in spring 2006, 21 were killed. In the summer of 2006, over 500 red "flight diverters" (320 mm long, 175 mm diameter) were installed at 5 m intervals along a 1.5 km length of the power lines. In the spring of 2007 only one mute swan was killed through power line collision, while in spring 2008 none were killed.

The perpendicular distances over which bird carcasses were found on the ground from under the overhead power cables ranged from 10-351 m. This should be taken into account when designing future collision mortality surveys for similar power lines. It is recommended that appropriate bird flight diverters are fitted as routine best practise when installing any new overhead power lines.