NORTH AMERICAN GULLS AND THEIR ALLIES. 
Forms Breeding in the Arctic but Occurring in the United States in Winter 
or in Migration. 
Skua (Megalestris shua). 
Pomarine jseger (Stercorarius pomarinus). 
Parasitic jseger (Stercorarius parasiticus). 
Long-tailed jaeger (Stercorarius longicau- 
dus). 
Ivory gull (Pagophila alba). 
Kittiwake (Rissa tridactyla tridactyla). 
Pacific kittiwake (Rissa tridactyla polli- 
caris) . 
Glaucous gull (Larus hyperboreus). 
Iceland gull (Larus leucopterus) . 
Kumlien's gull (Larus kumlieni). 
Great black-backed gull (Larus marinus). 
Short-billed gull (Larus brachyrhynchus) . 
Heermann's gull (Larus heermanni). See 
note. 
Bonaparte's gull (Larus Philadelphia). 
Sabine's gull (Xema sabini). 
Note. — Heermann's gull breeds south of the United States and migrates north 
after the breeding season. 
MIGRATION. 
All the gulls of North America are migratory, but the distances 
traversed by the several species in migration vary widely. Some of 
them, notably Ross's gull and the red-legged kittiwake, remain near 
the Arctic throughout the year, and retreat southward in winter for 
only a few hundred miles. At the other extreme is Sabine's gull, 
which breeds north of the Arctic circle and winters on the coast of 
Peru, more than 5,000 miles away. Franklin's gull does not breed 
so far north as Sabine's gull, but it goes enough farther south on the 
coast of Chile to make its migration route fully 5,000 miles in length. 
Most of the gulls and their allies travel much shorter distances in 
their migrations, and comparatively few individuals winter as far as 
2,000 miles from the breeding grounds. 
Two gull-migration routes deserve special mention: Bonaparte's 
gull breeds about fresh water in the subarctic parts of northwestern 
North America, whence many individuals in fall migration travel 
3,500 miles to the southeastward, reaching the Labrador coast by 
way of Hudson Bay before they turn southward toward their winter 
home on the coast of the South Atlantic States. The migration of 
Heermann's gull is unique among North American gulls, in that the 
species breeds south of the United States and at the end of the 
nesting season migrates north by thousands and swarms along the 
Pacific coast of the United States, even journeying to British Colum- 
bia. The birds remain on the California coast all winter and at the 
approach of the breeding season depart southward to their summer 
home. 
ANNOTATED LIST OF SPECIES. 
SKUA. Megalestris skua (BRtrNNiCH). 
The skua breeds in Iceland and on the Faroe and Shetland Islands. 
Though reported as breeding in North America, there seems to be 
no proof that it has ever nested in the Western Hemisphere, even in 
Greenland. The bulk of the birds winter off the coast of Europe 
south to Gibraltar, but the species is not rare at this season around 
