Electricity transmission and distribution grids are expanding rapidly worldwide which has significant negative impacts on biodiversity. In particular, overhead power lines still continue to increase in number as well as in overall area. Birds of many species are vulnerable to interactions with electrical transmission systems. Depending on the type of construction used, power poles and power lines may cause fatal injuries for birds. This is particularly true for large birds such as raptors, storks, herons and similar creatures. Collisions and electrocutions are still an important, continuing mortality factor for several species of birds, despite measures to ameliorate this issue being implemented by utilities
This is particularly significant where dense constructions of power lines intersect with migratory routes, for example, in Central Europe or the Western United States.
Power lines need to be designed to minimize the loss of bird life and consequent disruption of power transmission. Unfortunately large metal lattices, such as pylons and cellular transmission towers can be attractive nesting sites for some kinds of birds, which can prove problematical: not simply birds getting electrocuted, but branches and feces can cause power interruptions. If the interlopers are from protected species, then the power company may not be able to remove the nest if there are eggs or young inside.
Raptors often find transmission towers extremely useful perches to look out for prey: this is particularly the case where those lines are in areas of few trees.
Utilities need to ensure that there is an Avian Protection Plan. Power lines will need to ensure there is adequate separation between components to reduce the potential for electrocution: this might be as much as 60 inches (150 cm) for large species like eagles.
The Avian Protection Plan should identify bird-protective construction designs, retrofitting options, approved avian protection devices, careful siting and construction, as well as other procedures to ensure avian protection.