They're all over the place here, and they are for larger birds (Hawks, Crows, Falcons, Eagles...) In a 5 mile lineset I drive most every day they went from triangular to horizontal with these bird things; back and forth a number of times... Where there's a three phase airswitch bar (if that is even the right name...) I can understand, but is there an advantage to two of these per pole vs. the triangular pattern?
They are both perches and guards. As a perch it keeps the bird further away from the energized equipment, and as a guard, at least in the pic above, on the lower arm, it seems to discourage a bird from landing on the lower arm.
From the zine article mentioned above
[This message has been edited by rmiell (edited 02-08-2006).]