The Herring Gull 
Taken in San Luis Obispo County Photo by the Author 
THE MARINER 
with white. All birds which show mixed characters, such as black tail 
and wing-quills, with mottled plumage, etc., are juveniles of the second 
or third year. 
The most persistent juvenile characteristic in the case of the common 
larger gulls ( Larus glaucescens, occidentalism argentatus, californicus, dela- 
warensis, and brachyrhynchus) is a gradually diminishing area of black 
upon the beak (although this in its reduced form is an adult character¬ 
istic of L. calif ornicus and L. delawarensis). With advancing age gulls 
tend to become lighter in coloration; and in extreme examples (as in the 
case of certain Western Gulls) the black wing-tips bleach nearly to white¬ 
ness, although the characteristic pattern may still be dimly discerned. 
Size is also a very variable characteristic in the larger gulls, and 
it is impossible to distinguish Larus argentatus from glaucescens on the 
one hand, or calif ornicus on the other, from the standpoint ot size alone. 
And while we are about it, we may as well repeat that the color of 
the feet and legs (tarsi) affords one of the most valuable distinctions in 
the field recognition of all gulls. The Herring Gull belongs to the group 
having red legs, and only by this mark may it be infallibly separated 
from the California Gull which has gray-green legs. 
The Herring Gull begins to return from its northern breeding grounds 
