Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

Providing evidence to improve practice

Individual study: Marking earth wires with yellow aviation balls reduces avian collision mortality in South Carolina

Published source details

Savereno A.J., Savereno L.A., Boettcher R. & Haig S.M. (1996) Avian Behavior and Mortality at Power Lines in Coastal South Carolina. Wildlife Society Bulletin, 24, 636-648


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Mark power lines to reduce incidental bird mortality Bird Conservation

A paired sites study in 1991-4 in coastal wetlands in South Carolina, USA (Savereno et al. 1996), found a 53% reduction in collision mortalities at a 3.9 km span of 115 kV transmission lines where the static wires were marked, compared to a 1.2 km unmarked span. A higher proportion of birds approaching marked wires at the most dangerous height (between transmission wires and earth wire) reacted to them, compared to unmarked wires (98% of 9,819 flocks vs. 89% of 4,209 flocks respectively) and fewer crossed the wires at this height (4% vs. 24%). However, overall, a higher percentage of birds reacted to lines at unmarked spans (40% of 17,391 flocks vs. 34% of 64,512 flocks). The experimental span was marked with yellow aviation balls (30 cm in diameter with a vertical black stripe) at 61 m intervals, staggered to give the appearance of a 30.5 m spacing.