Large falcons (genus Falco) do not build their own nests and, in North America at least, usually nest on high cliffs. Occasionally they nest in abandoned stick nests built by another large bird on the cliff. In Asia and particularly South Africa, they sometimes nest in stick nests on electrical transmission towers. This use of electric transmission towers was recently (1980) reported for the Prairie Falcon (Falco mexicanus) in North America but is unknown, except for 1 anecdotically documented use of an "electric-power pole" at the turn of century in California, for the Peregrine Falcon (Falco peregrines) in North America. Here we report such nesting of the peregrine in North America and additional tower nestings for the Prairie Falcon.
Bunnell, Stephen T.; White, Clayton M.; Paul, Don; and Bunnell, S. Dwight
"Stick nests on a building and transmission towers used for nesting by large falcons in Utah,"
Great Basin Naturalist: Vol. 57
, Article 10.
Available at: http://scholarsarchive.byu.edu/gbn/vol57/iss3/10