T. Cade 1958 Falco vestigiales 24 July Colville River - ca 20 min. above Chistat While we were at a peregrine aerie - on the right limit below the double-knife blade bluff - a large bluish gray falcon - larger than the 9 peregrines - which I thought must be a gyrfalcon - flew into the area from down river - apparently attracted by the diving and screaming of the peregrines. At once it attacked the 9 peregrines and bound to their legs. They fell fluttering through the air for several yards before breaking loose. This did not deter the peregrines, however, which in turn began stooping at the gyrfalcon. I took a long shot at the gyrfalcon but missed. Thereupon, this caused it to fly off down river with the peregrines in hot pursuit. The falcons stayed with them for about 2 minutes then returned. This was the only gyrfalcon seen on the trip between Colamreogazik and Chistat - a stretch where a total of 6 nesting sites is known. The correlation between nesting of gyrfalcons and numbers of ptarmigan is therefore perfectly confirmed by this year's situation.