Bird Protection

White stork got killed by electrocution. Photo: Langgemach, LUA.

Electrocution

Above all, power lines are a danger to birds. Every year several thousand birds die from electric shocks or collisions with power lines. Birds are electrocuted when their bodies happen to touch two areas on the power lines which have different voltages. If a bird perches on a power line, and then, almost at the same time touches another part of the power line carrying a different voltage, the current will pass through its body causing electric shock resulting in severe burns or death. Such accidents happen primarily with large birds on medium voltage power lines. 

Birds colliding with power lines

Many bird species are at risk of colliding with power lines. The two dimensional way in which birds see makes it difficult for them to actually catch sight of the lines. In particular, the earth wires at the very top, hanging individually and especially thin, are danger when birds try to fly over the more visible bunch of conductors. Particularly nocturnal birds and migratory birds are unable to get used to the presence of individual power lines, and are therefore most at risk of collision. Spcific mMarkers attached to the erth wires make the power lines more visible and can significantly reduce the collison risk for birds.

Link: NABU: Suggested Practices for Bird Protection on Power Lines

Landscape

Overhead power line near Krefeld. Photo: Schrader, DUH.

Wherever they are situated, power lines always alter the landscape. One important factor in route choice is people's acceptance.
Distances to housing therefore play a decisive role in planning procedures. When the route has been definitely decided then the question is: In which order should the pylons be erected so that they are optimally adapted to conditions in the locality?
In an ideal situation, the way they look from a distance and related visual axes would also be considered. However, in some regions overhead power lines run directly over residential areas or close to houses. Germany is densely populated, therefore, even when the best choice has been made from several possible choices, many power lines are still within sight of some residents.

EM-Fields

Electromagnetic fields around extra high power voltage lines

Overhead power lines (alternating current) are the main source of constant, low frequency electrical and magnetic fields, commonly known as electrosmog. People living close to such extra high voltage power lines are more exposed to electrosmog than others. 
 more

Links:

ICNIRP: Various studies

WHO: Electromagnetic fields and public health- Exposure to extremely low frequency fields 

NIEHS (USA): Assessment of Health Effects from Exposure to Power-Line Frequency Electric and Magnetic Fields