Birds sit on power lines because they like the high vantage point and because it protects them from ground predators. From power lines, birds can also search for insects and rodents at their leisure.
Birds find power lines convenient places to perch and preen or to congregate in groups. They sometimes even grow comfortable enough to build nests there. Power lines are a perch of choice because of their height; before they came along birds settled for tall trees and other high structures.
Birds don't have to worry about electrocution because they usually only touch one wire at a time, and touching two is required to allow electricity to flow through an organism. One power line is an open circuit that is safe. However, two connected power lines create a closed circuit, causing damage. Smaller birds are more likely to roost on power lines unscathed. However, large birds with long wingspans such as owls, eagles and hawks are more likely to touch another power line with their spread wings accidentally. More than 174 million birds are electrocuted every year, 1,000 of which are large birds electrocuted because of transmission lines. However, not all electrocutions are a result of power lines.