RICHMOND, Va. (AP) – Bridges in coastal Virginia have played a key role in helping boost the breeding population of large birds.The Center for Conservation Biology at the College of William and Mary says peregrine falcons have consistently nested on the Robert O. Norris bridge, which spans the Rappahannock River, for 21 years.The center said bridges have supported more than 30 percent of the known breeding population in the state for peregrine falcons since 1993.The conditions of the bridges mimic those of cliff formations not naturally found on the coast. Virginia’s large bird population has made a dramatic comeback in recent years after being decimated by DDT and other pollutants.