|Photo from Wikimedia Commons|
I think the main reason birds sit on high wires is because it’s a nice resting area. Power lines like trees, provide safe, high perches that allow smaller birds to survey the surrounding area for predators. Fall is when nesting is over and huge flocks begin to form.
However most birds do have a special middle-ear receptor called the Vitali organ, which can sense incredibly small changes in barometric pressure. A frenzy of activity at feeders and birds flying low or perching on low power lines could also be signs of the swiftly falling air pressure from an incoming storm.