Collision and electrocution by powerlines are considered to be a major cause of death for large-bodied bird species such cranes and raptors. Given that the number of powerlines is set to rise in the coming years, mitigation measures are urgently required to reduce the negative impact of powerlines on birds.
Power lines are a major cause of non-natural mortality for various species of birds across the globe (Lehman et al. 2007; Jenkins et al. 2010). In the United States alone, it is estimated that up to 64 million birds are killed each year at power lines (Loss et al. 2014). Collisions with wires affects large-bodied and migratory species characterized by low flight manoeuvrability (e.g. cranes, swans and bustards), whilst electrocutions on pylons significantly affect large raptors (Rubolini et al. 2005; Andriushchenko & Popenko 2012).
Ludwig’s Bustard Neotis ludwigii is a large and wide-ranging bird endemic to south-west Africa. Due to its field of vision, when scanning for foraging sites it is blind to what lays ahead making it extremely susceptible to collisions with power lines during its daily flights to and from roost sites (Martin & Shaw 2013). An estimated 4,000-11,900 birds are killed annually on high-voltage transmission lines (Jenkins et al. 2011). With the population estimated to be 114,000 (Shaw et al. 2015), the current level of mortality is unsustainable. This resulted in the up listing of its conservation status from Least Concern to Endangered.
In South Africa, mortality from power lines is widely considered to be an important contributory factor in the decline in range and numbers of the Endangered Cape Vulture Gyps coprotheres and the Critically Endangered African White backed Vulture G. africanus. Vultures routinely perch and roost on power line structures. Due to their large wingspan they can easily span the distance between energized and ground components of power lines (Lehman et al. 2007). Vultures are long lived species with low reproductive rates and low natural mortality rates; increases in the mortality rate, as a result of electrocution, upset the population dynamics and lead to a regional population decline. Population models indicate that Cape Vulture populations in areas with high concentration of powerlines are likely to go extinct, from electrocution mortality alone, within 20–35 years (Boshoff et al. 2011).
The global network is growing at a rate of about 5% annually, due to increasing energy demands. Unless appropriate mitigation measures are put in place the number of bird fatalities is likely increase (Perez-Garcia et al. 2011). In Spain, the Spanish Imperial Eagle Aquila adalberti (Vulnerable) loses 30% of juveniles to electrocution on power lines each year. Simple, inexpensive alterations to the design of power line poles could reduce annual mortality by more than 50% (Janss and Ferrer 2001).
Related Case Studies in other sections
Andriushchenko Yu, A. and Popenko, V. M. (2012) Birds and power lines in Steppe Crimea: positive and negative Impacts, Ukraine. Raptors Conserv. 24: 35–41.
Boshoff, A. F., Minnie, J. C., Tambling, C. J. and Michael, M. D. (2011) The impact of power line-related mortality on the Cape Vulture Gyps coprotheres in a part of its range, with an emphasis on electrocution. Bird Conserv. Int. 21: 311-327.
Janss, G. F. E. and Ferrer, M. (2001) Avian electrocution mortality in relation to pole design and adjacent habitat in Spain. Bird Conserv. Int. 11: 3–12.
Jenkins, A.R., Shaw, J.M., Smallie, J.J., Gibbons, B., Visagie, R. and Ryan, P.R. (2011) Estimating the impacts of power line collisions on Ludwig’s Bustards Neotis ludwigii. Bird Conserv. Int. 21: 303-310.
Jenkins, A. R., Smallie, J. J. and Diamond, M. (2010) Avian collisions with power lines: a global review of causes and mitigation with a South African perspective. Bird Conserv. Int. 20: 263–278.
Lehman, R. N., Kennedy, P. L. and Savidge, J. A. (2007) The state of the art in raptor electrocution research: a global review. Biol. Conserv. 126: 159–174.
Loss, S. R., Will, T. and Marra, P. P. (2014) Refining estimates of bird collision and electrocution mortality at power lines in the United States. Plos One. 9(7): e101565. doi:10.1371/journal.pone.0101565
Martin, G. R. and Shaw, J. M. (2010). Bird collisions with power lines: failing to see the way ahead? Biological Conservation. 143: 2695-2701
Perez-Garcia, J. M., Botella, F., Sanchez-Zapata, J. A. and Moleon, M. (2011). Conserving outside protected areas: edge effects and avian electrocutions on the periphery of Special Protection Areas. Bird Conserv. Int. 2: 296-302
Rubolini, D., Gustin, M., Bogliani, G. and Garavaglia, R. (2005) Birds and powerlines in Italy: an assessment. Bird Conserv. Int. 15: 131–145.
Shaw, J. M.; Jenkins, A. R.; Allan, D. G.; Ryan, P. G. 2015. Population size and trends of Ludwig’s Bustard Neotis ludwigii and other large terrestrial birds in the Karoo, South Africa. Bird Conserv. Int. 26: 69-86.
Compiled: 2004 Last updated: 2017
BirdLife International (2017) Collisions and electrocutions pose real threats for young and migrating birds. Downloaded from http://www.birdlife.org on 28/10/2020