Individual study: A review of the success of power line mitigation measures in reducing mortality of cranes
Davis C. (1998) A review of the success of major crane conservation techniques. Bird Conservation International, 8, 19-29
Cranes are among the most endangered birds in the world, with several species considered to be globally threatened. A number of crane conservation techniques exist, including legal protection, habitat protection, artificial feeding, manipulation of eggs, power line modification and captive breeding and releases. As part of a review of the relative success of these different techniques, this study provides a summary of the evidence for the effectiveness of power line mitigation measures in reducing mortality of cranes.
A literature review was conducted of the effectiveness of measures to modify, re-route or remove power lines in reducing mortality of cranes due to collisions. Modification of power lines was defined as the attachment of visual markers, such as swinging plates, coloured aviation balls or spiral vibration dampers. The responses of the affected crane populations were examined, with information on mortality used to evaluate the relative success of the mitigation measures.
Following the attachment of tags or tubes with coloured warning stripes and the partial removal or transfer of wires from particular trouble spots in Hokkaido, Japan, in the 1970s, the number of reported mortalities of red-crowned cranes Grus japonensis due to collisions with power lines decreased from 56 between 1970-1974 to 15 during 1980-1984 (Masatomi 1991). Marking of power lines at Monte Vista National Wildlife Refuge, Colorado, USA, with swinging metal plates or spiral vibration dampers reduced collision mortality of sandhill cranes Grus canadensis (and waterfowl) by 63% and 61% respectively (Brown and Drewien 1995). The use of yellow aviation balls on power lines near the Platte River in Nebraska also resulted in a significant reduction in collision mortality of sandhill cranes (Morkill and Anderson 1990).
The author concludes that the modification or removal of power lines is a worthwhile conservation technique, which is effective in reducing mortality in localised and endangered crane populations and sustainable over the long term.
Brown W.M. and Drewien R.C. (1995) Evaluation of two power line markers to reduce crane and waterfowl collision mortality. Wildlife Society Bulletin 23: 217-227.
Masatomi H. (1991) Population dynamics of red-crowned cranes in Hokkaido since the 1950s. Pp. 297-299 in Proceedings of the 1987 International Crane Workshop. International Crane Foundation, Baraboo, Wisconsin, USA.
Morkill A.E. and Anderson S.H. (1990) Effectiveness of marking powerlines to reduce sandhill crane collisions. Wyoming Cooperative Fish and Wildlife Research Unit, Laramie, Wyoming, USA.
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