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Providing evidence to improve practice

Individual study: Use of yellow aviation balls on the earth wire of transmission lines reduces collision mortality in sandhill cranes Grus canadensis near the Platte River, Nebraska

Published source details

Morkill A.E. & Anderson S.H. (1991) Effectiveness of Marking Powerlines to Reduce Sandhill Crane Collisions. Wildlife Society Bulletin, 19, 442-449


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 replicated, paired sites study (Morkill & Anderson 1991) in south-central Nebraska, USA, between 1988-1990, found that marking the static wire of nine spans of high-voltage transmission wire reduced collision mortality in sandhill cranes Grus canadensis by 66% compared with unmarked spans (11 fatalities vs. 25). Crane flocks were also more likely to increase altitude (454 flocks vs. 397) or change direction gradually (114 vs. 92) when flying close to marked spans, but were less likely to react quickly (and potentially dangerously) to marked spans (19 vs. 36) or show no reaction (1,200 vs. 768). Experimental spans were 1-2.5 km in length and marked with yellow aviation balls (30 cm in diameter with a vertical black stripe) at 100m intervals, staggered to appear more closely spaced.