Conservation Biology Group

Threats and solutions

Electrocution of birds and collision with power lines: Solutions to a global problem

Power lines are infrastructures that might cause negative impacts on the environment. Some of these impacts are electrocutions and collisions of birds that kill hundreds of thousands every year. Electrocution occurs on distribution lines (15-66 kV), when a bird comes into contact with two wires or when it perches on a conductive pylon (for example, a metal structure) and comes into simultaneous contact with a wire. On the other side, collision occurs on both distribution and transport lines, when the bird collides with one of the wires, generally the earth wire, which is less visible. Nevertheless, two studies conducted by the Biology Conservation Group try to reduce these threats to birds.

Bird death by electrocution is a global problem that has been aggravated by increases in the energy demand of certain regions and is particularly prevalent in natural areas where the introduction of power lines is a cause of significant disruption to local species. In Catalonia, electrocution is the primary cause of death of the Bonelli’s Eagle (Aquila fasciata), and across the rest of the Iberian Peninsula it affects particularly large numbers of the endangered Iberian Imperial Eagle (Aquila adalberti) and many other ecologically valuable species. In the United States, the problem has a particular impact on the highly symbolic Bald Eagle (Haliaeetus leucocephalus). In Africa, common victims include the Cape Vulture (Gyps coprotheres) and the Egyptian Vulture (Neophron percnopterus).

In Catalonia, there are more than 1000 different models of electricity pylons, which pose different levels of threat to birds. The article published in the Journal of Wildlife Management confirms the validity of the predictive model designed by the UB research group to determine the risk of electrocution according to pylon design and location, as well as verifying the effectiveness of corrective measures implemented at electrocution blackspots. According to this study, the threat posed by a pylon depends on the electrotechnical design and the natural features around it. If we apply the predictive model we can correct power lines more effectively without having to apply measures to entire spans of the transmission network. The model makes it possible to select and act on the most dangerous pylons and correct them effectively. Applying correction measures to only 6 % of the most dangerous pylons could reduce bird mortality by up to 70%.

The article reviews more than ten years of pioneering work by the UB team on the detection and correction of potentially dangerous pylons and the evaluation of anti-electrocution measures over an area of 210,000 hectares in the Barcelona pre-littoral mountains. In the design of the predictive tool, the team modelled the risk of bird electrocution posed by 3,869 electricity pylons. Next, the team worked with power companies to apply corrective measures to the most dangerous pylons identified by the model (those with wires or connectors above the cross-arms and located in natural habitats or areas selected by bird species for specific activities). The study confirms that these anti-electrocution measures are effective and reduce the number of birds electrocuted in their natural habitats.

Raptors or crows that are accustomed to use the electrical pylons as hunting lookouts or as places to rest
The article published in the Journal of Wildlife Management confirms the effectiveness of corrective measures designed by the UB to avoid bird death by electrocution

On the other hand, the article published in the journal Bird Conservation International suggest that collision is more serious than previously thought on the survival of endangered species such as the Bonelli’s Eagle. Collision with power lines is a lesser-known problem than electrocution and is harder to detect because it can occur at any point along the transmission line. In the case of power lines, the bird collides with one of the wires, generally the earth wire, which is less visible. In the study, the Group presents a predictive model for determining which lines and spans create the greatest risk of collision, describing the most effective strategies for reducing the number of accidents caused by transmission lines. The results of the article, based on a radio-tracking study of Bonelli’s Eagle populations in the Barcelona and Tarragona area, suggest that collision risk is influenced by a number of factors, including the topography of surrounding terrain and the proximity of lines and pylons to nests and other areas used frequently by local species.

These studies were supported by the Miquel Torres Foundation, the Barcelona Regional Council and the companies FECSA-ENDESA, Estabanell i Paysa S.A., Electra Caldense S.A. and Red Eléctrica de España, S.A. With these studies, the Group proposes conservation strategies to the authorities and companies working on environmental issues in regions affected by the impact of power lines.

For further information:
  • TINTÓ, A., REAL, J. & MANYOSA, S. 2010 Predicting and correcting electrocution of birds in mediterranean areas. Journal of Wildlife Management, 74(8): 1852-1862. doi: 10.2193/2009-521
  • ROLLAN, À., REAL, J., BOSCH, R., TINTÓ, A. & HERNÀNDEZ-MATÍAS, A. 2010. Modelling the risk of collision with power lines in Bonelli’s Eagle Hieraaetus fasciatus and its conservation implications. Bird Conservation International, 20: 279-294. doi: 10.1017/S0959270910000250