Cf. North, Nests and Eggs of Australian Birds, Sydney, 1889, pp. 11-13.
Cf. Ibis, 1879, pp. 413, 414.
Professor Newton and other writers seem to consider that the true Gyr-Falcon only inhabits Scandinavia and H. candicans Greenland and Arctic America; but this does not preclude occurrences elsewhere. Cf. however, Ibis, 1889, pp. 143-144.
Cf. H. Gadow, Bronn's Thier-Reich, Aves, Syst. Theil. 1893, pp. 160-164.
H. Gadow, Bronn's Thier-Reich, Aves, Syst. Theil. 1893, p. 176.