Populations of breeding Swainson's Hawks (Buteo swainsoni), Red-tailed Hawks (B. jamaicensis), and Golden Eagles (Aquila chrysaetos) present in 1999 were compared with populations present between 1975 and 1982 at a 129-km2 site in north central Oregon. Populations of Red-tailed Hawks and Golden Eagles remained unchanged, but the number of Swainson's Hawks pairs increased from 15 to 17. In 1999 Golden Eagles used nests occupied between 1975 and 1982, and 7 of 31 pairs of Red-tailed Hawks used nests occupied in earlier years. No Swainson's Hawks nested in trees occupied earlier. Few changes in territorial boundaries were detected.
Janes, Stewart W.
"Breeding populations of Swainson's Hawks, Red-Tailed Hawks, and Golden Eagles in north central Oregon: 1975–1982 and 1999,"
Western North American Naturalist: Vol. 63
, Article 10.
Available at: http://scholarsarchive.byu.edu/wnan/vol63/iss3/10