8 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



Enemies. — Manniche (1910) relates the following two incidents in 

 which the gyrfalcons were attacked by other birds: 



A falcon was in the most violent manner attacked by two Ravens. The 

 quarrelling birds flew for a while around high up in the air uttering angry cries, 

 after which the Ravens descended and took place side by side on a rock evidently 

 lurking after Lemmings, the holes of which were numerous around the place. The 

 falcon also settled with the same intention on another rock some 50 meters from 

 the Ravens. At my approach the birds rose again in the air and immediately 

 continued their battle. The Ravens seemed much superior to the falcon, which 

 therefore showed an inclination to fly away to avoid their rough treatment. 



The battle at last took place just over my head, and I shot one Raven in order 

 to make the fight more even. 



Frightened by the shot the two other birds flew away in different directions, but 

 they soon met again, and took up the battle nearer to the coast. Here the falcon 

 got relief from two birds of its own kin, and now the Raven was obliged to depart 

 hastily, while the three falcons settled on the summit of a rock. 



Not rarely I observed falcons pursued by Skuas (Lestris longicauda) . At the 

 end of August the young Skuas will frequently be sitting around on stones, still 

 cared for by their parents, which with extreme violence will guard their offspring 

 against attacks from falcons. The Skuas exceed by far the Gyrfalcons in ability 

 of flight, and the falcons therefore always wish to escape the pursuit and retire to 

 the rocks. Most frequently 3 or 4 Skuas would join in an attack; the battle would 

 usually be fought out immensely high up in the air. 



Field marks. — This bird can be recognized as a falcon by its long 

 pointed wings and its manner of flight, rapid wing beats with occasional 

 short sailings, or a stationary, hovering flight. But only by its greater 

 size can it be known as a gyrfalcon. If it has a wholly white breast 

 and is mainly white above, it is an adult white gyrfalcon; even young 

 birds of this race are nearly white below and largely white above. 

 All other gyrfalcons are considerably mottled or streaked on the under 

 parts and dark colored above. Gyrfalcons are not likely to be seen 

 within the United States except in winter. 



Winter. — Some of the gyrfalcons remain far north throughout the 

 winter, wherever they can find a sufficient food supply. But, as the 

 ptarmigans migrate southward, many of the falcons have to follow 

 them. White gyrfalcons are much commoner in winter than in sum- 

 mer in southern Greenland. Bernhard Hantzsch (1929), writing of 

 northeastern Labrador, says: 



It most probably does not breed until northward of our district, but reaches it 

 occasionally as a visitor and migrant. The birds, especially in autumn, regularly 

 follow the flights of the ptarmigan which make their favorite food. However, 

 they feed upon everything else possible, apparently not only on living creatures. 

 The inhabitants not seldom find them during the winter in the baited fox-traps, 

 by which the birds become annoying to them. These more or less light winter 

 visitors and migrants are far more frequent than the dark breeding birds; indeed, 

 in many years of abundant snow they are said to occur in rather large numbers. 



Mr. Turner says that this "bird is far more numerous from Septem- 

 ber to April than at other times" in Ungava. At this season it 



