20 
GULLS AND TERNS 
and legs black ; tarsus shorter than middle toe with claw ; hill yellow, 
with greatest depth at base ; tail slightly emarginate, or forked. Adults: 
hack and wings light bluish gray, five outer primaries tipped with black; 
rest of plumage pure white. Young: like adults, but with black or slaty 
on back of neck and across ear coverts. Length : 16.00-17.70, wing 12.25, 
bill 1.40-1.50. 
Distribution. — North Pacific and Bering Sea; south in winter casually 
to Lower California. 
Nest. — On inaccessible shelves of rock, made of grass and moss cemented 
with mud. Eggs: usually 2, gray, spotted with brown. 
The kittiwakes reach Alaska before the ice breaks up, and hunt 
for food in the tide cracks along shore. In the breeding season 
they take to the cliffs of the mainland or the rocky islands. From 
the end of August they hunt in the inner bays and mouths of small 
streams, but as they are strictly tide-water birds rarely go up the 
rivers. In October the ice forming on the bays drives them south. 
GENUS LARUS. 
General Characters. — Bill deeper through angle of lower mandible than 
through nostril; tail square across end ; hind toe small but perfect. 
KEY TO SPECIES. 
1. Size large, wing 15.00 or more. 
2. Wing without any black. 
3. Quills white or pale gray shading to white at ends. 
glaucus, p. 21. 
3'. Quills clear gray with white tips .... glaucescens, p. 21. 
2'. Wing quills partly black at all times. 
3. Mantle dark slaty gray in adult.occidentalis, p. 21. 
3'. Mantle light gray in adults. 
4. Lower mandible in adult with subterminal spot of red and spot of 
black.californicus, p. 23. 
4'. Lower mandible in adult with subterminal spot of red only. 
5. Mantle delicate pearl gray.argentatus, p. 22. 
5'. Mantle slightly darker gray.vegae, p. 23. 
l'.Size medium or small, wing under 15 (rarely over in delawarensis). 
2. Breast always dark slaty gray.heermauni, p. 24. 
2'. Breast always white in adult, mottled in young. 
3. Head never black ; white in adults. 
4. Bill yellowish, with black band near end in adults. 
delawarensis, p. 23. 
4'. Bill greenish, without black band. 
5. Third quill with subterminal white spot in adult. 
brachyrhynchus, p. 24. 
5'. Third quill without subterminal white spot in adult. 
canus, p, 24. 
3'. Head black in summer adults, size small. 
4. Bill and tips of outer quills black . . Philadelphia, p. 26. 
4'. Bill dark red in adult, quills not tipped with black. 
5. Three outer quills mainly black .... atricilla, p. 25. 
5'. Five outer quills with tips and base white . franklinii, p. 25. 
