project news

Birds & Bats: Life on the Line

News item submitted by Flora O'Brien & Ben Margerison
News item dated 6 Dec 2010


Power lines have long been recognised as death traps for birds. Electrocution by power lines is an issue particularly for birds of prey, such as the Bonelli's Eagle (Aquila fasciata) and the endangered Iberian Imperial Eagle (Aquila adalberti), since their large wing span may mean they touch two parallel power lines at once. As the global demand for energy has risen, more and more power lines are sprouting up all over the world.

Birds are electrocuted if they come into contact with either two wires or a wire and a live pylon simultaneously. Additionally, birds have been known to die from collision with power lines, particularly with earth wires as they are less visible. The risk of fatality by electrocution from a power line or pylon depends on the model. A paper published in the Journal of Wildlife Management reports a model from which the risk of electrocution can be calculated, taking into account both the technical design of the pylon and the surrounding landscape. Reviewing a decade of work by researchers from the University to Barcelona, the study investigated the effectiveness of anti-electrocution measures over 210,000 hectares in the Barcelona pre-littoral mountains.  The article concluded that preventative measures can be very effective in reducing the frequency of electrocution-related bird fatalities. One of the best ways to prevent the death of birds by power lines is to lay the lines underground, as has already been done in several countries such as Germany; unfortunately this is not practically and financially feasible in all countries.

In addition, there is a possibility that power lines could pose a threat to bat populations, such as those being studied by the Frontier team on Mafia Island, Tanzania. It has indeed been reported that bats are being killed by the power lines, especially large species. In 2011, it is hoped that Frontier can gain funding for a new project to assess the effect that power lines could have upon mortality amongst the eight bat species found on Mafia Island. Species of fruit bats such as Pteropus seychellensis comorensis, which are large flyers, share some characteristics with the bird species that are particularly affected by overhead power lines, and could therefore be affected as well. Currently there is very little information on the effect of power lines on bats, this project could therefore shed light onto what could be an important conservation issue for bats.


Find out more about the Frontier Tanzania Marine project.