226 
CHARADRIIFORMES 
Field Marks. Size, smaller than a Herring Gull and larger than the Ring- billed, is 
generally suggestive. The red and black spot on the bill of the adult when seen is deter- 
minative. Yellowish or greenish legs distinguish it from the Herring Gull and the red on 
the bill from the Ring-billed. 
In juvenility it is never as dark as the Herring Gull in the first year. Eye-sight 
records of some plumages are unreliable. 
Nesting. On the ground, on low, flat islands, as a rule marshy, or near the water. 
Distribution. Western North America. Breeding in the interior in the Prairie 
Provinces (Saskatchewan and Alberta), north to the Arctic circle. Migrating to the 
Pacific coast of British Columbia southward. Winters south of our boundary. 
Many of the records of the Herring Gull breeding in the prairie lakes 
apply to this species. Owing to the similarity of the two birds their 
occurrences have not been well delimited. This is probably the common 
large gull breeding south of the Canadian National Railway tracks in 
Saskatchewan and Alberta. Its occurrence in Manitoba has yet to be 
recorded. 
54. Ring- billed Gull. le goIsland criard ou la mauve CRIARDE. Larus delauaren- 
sis. L, 19-75. Similar to the Herring and California Gulls, but slightly smaller, and 
having a black ring about the bill near the tip (Figure 
328) and with yellow legs and feet. 
Distinctions. East, central, and west. Smaller 
size, lack of red and the presence of dark ring on bill, 
and yellow legs, differentiate the Ring-bill from the 
Herring Gull. 
From the California Gull, smaller size, in duly 
sexed specimens, and lack of red on the bill. 
From the Short-billed Gull, larger size and 
presence of dark ring on bill. 
In juvenility, distinctions are finer. The following 
schedule of characters may assist: 
Figure 328 
Bill of Ring-billed Gull; 
scale, J. 
Figure 329 
Details of Ring-billed Gull: 
Wing of adult, tail of juvenile; scale, 
Medium-sized gull, L, 19-75. 
Comparatively light, much spotted; tail mottled, with exten- 
sive subterminal band; bill dark, with flesh-coloured base, 
feet dark or flesh-coloured First autumn 
Light; tail white with conspicuous band; bill yellowish with 
more or less ring; feet yellowish or flesh-coloured (Figure 
329) Immature 
Light; tail white; bill yellow or greenish yellow with dark ring; 
feet yellow; eyelids and gapes red Adult 
