The Herring Gull 



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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, occidental-is, argentatus, californicus, dela- 

 warensis, and brachyrhynchiis) is a gradually diminishing area of black 

 upon the beak (although this in its reduced form is an adult character- 

 istic of L. californicus 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 californicus on the other, from the standpoint of 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 



1396 



