It must not be forgotten that the Northern falcons, or, as they are generally called, the gyrfalcons, are entitled to rank as British birds, although they are rare visitors to these Isles. They are (1) the gyrfalcon or Norwegian variety (_Falco gyrfalco_), (2) the Iceland falcon (_Falco islandus_), (3) the Greenland falcon (_Falco candicans_). The gyrfalcon is a very rare visitor here, two recorded specimens only having been obtained here and one of these is doubtful. The Iceland falcon is a rare visitor also, although identified examples have been obtained here from time to time. The Greenland falcon is an irregular winter and spring visitor, but there are more recorded instances of this species than in the case of the Iceland falcon. The former bird, the prevailing ground colour of which is white, is the most beautiful of all birds of prey. By some authorities it is considered merely a race of the Iceland falcon, which it resembles in size and habits. The eggs of the two birds resemble one another. All these Northern falcons are about the same size and larger than, though very similar in structure to, the peregrine falcon. Speaking generally, the difference in length is about 5 inches, in wing 2 inches. They have been very highly valued in Europe for hawking, and, as would be expected from their superior size and similar structure, are undoubtedly faster than peregrines. Writing in the _Field_ for March 15, 1923, Major Radclyffe says:[13] “All the gyrfalcons are much faster on the wing than peregrines, and having trained and flown both species of these falcons for many years I have been enabled to prove this beyond doubt.” The swift has still to be considered. There are three species of swifts which rank as British birds: the common swift (_Cypselus apus_), the Alpine swift (_Cypselus melba_), and the spine-tailed or needle-tailed swift (_Acanthyllis caudacuta_ or _Chaetura caudacuta caudacuta_). The Alpine swift is a rare visitor here, only about thirty having been satisfactorily identified at different times from April to October in different parts of these islands, but chiefly in the southern part of England. It breeds in mountains throughout Central Europe, and eastwards to India. The spine-tailed swift is even a rarer visitor here, only two recorded instances of specimens having been obtained--one in Essex in 1846 and one (said to have been in company with another) in Hampshire in 1879. It breeds in the mountains of North-eastern Asia, and in winter goes as far south as Australia. [Illustration: THE SPINE-TAILED SWIFT. By V. R. BALFOUR-BROWNE.]