.208 
grey ; wings and tail browner, latter barred 
with bluish grey and tipped with white ; 
below white with a broad slate brown 
moustachial stripe, the breast and abdomen 
with drop-shaped stripes and flanks barred ; 
bill bluish, tip black ; feet yellow. 
7*310a. Falco rusticolus islandus [partim] Briin- 
310b. 
nich, Orn. Bor., p. 2 (1764). 
Iceland Falcon. 
[Iceland. ] 
[Grey-backed form]. Slightly larger ; wing 
3 368, 2405 mm. ; above dark slate, barred 
with greyish white, the head streaked with 
dusky slate and buffish white; chin and 
throat white ; below white, chest streaked 
and belly and sides spotted with slaty 
black. 
Falco rusticolus alascanus Swann, Bull. 
B.O.C., xlii., p. 67 (1922). [2 Norton Bay, 
Alaska, Oct. 1879, E. W. Nelson, type in 
U.S. Nat. Mus., No. 96776.] 
{nom. nov. pro F. sacer [Forster] of Ridgw., 
nec auct.] 
Alaska Gyrfalcon. 
[Grey-backed form]. Smaller; wing g 
340-358, tail 210 mm.; wing 2 386-400, 
tail 220-230 mm. ; wing (type) 400 mm. ; 
darker, less grey than rusticolus, and with 
bars on wing-coverts and secondaries rather 
whiter and wider; above blackish slate, 
barred and edged with pale grey; head 
more uniform, hind neck mottled with 
white ; rump lighter and bluer ; primaries 
broadly barred with white on inner webs 
and with obsolete spots on outer webs ; 
tail evenly barred across with dark slate 
and greyish white; cheeks with distinct 
black moustachial stripe; below white, 
Iceland ; 
S. in winter to 
Brit. Isles, 
Europe and 
N.E. America. 
Alaska, breeding 
S. to 
St. Michael’s 
and Norton 
Bay, N. to 
Anderson 
River (?) ; in 
winter to 
S. Alaska, 
Prybilov Is., 
Brit. Columbia 
and Washington 
State. 
