^°'i9i4'^^] Strong, Habits of the Herring Gull. 27 



lens, and the other a folding tripod camera size 3j X 4j inches with 

 both a lens shutter and a focal-plane curtain shutter. The smaller 

 camera was more often used, and frequently with only one of the 

 two combinations of the convertible lens which it carried. I have 

 found a convertible lens exceedingly useful in bird photography as a 

 long-focus lens is frequently needed. It has been my experience 

 that it is not practicable to use large diaphragm openings in bird 

 photography because of the flatness of the field which they involve 

 when the camera is as near as is necessary for photographing 

 birds. I rarely use an opening larger than U. S. 8 or F. 11. 



'' III. Social or Community Relationships. 



An interesting analysis of a Herring Gull community has been 

 made by Herrick.^ He speaks of "family-units" and "family 

 domains" which he says are guarded "with relentless vigilance." 

 These precincts may be small and close together in a crowded 

 breeding place. 



There is also much evidence of cooperation. Thus Herrick men- 

 tions the fact that Herring Gulls will "attack a common enemy, 

 such as bird, beast or man, with a certain degree of concerted ac- 

 tion." 



Herring Gulls are frequently to be seen together in flocks away 

 from a breeding place. Mackay,- however, did not regard them as 

 truly gregarious. Thus he says "they apparently only come to- 

 gether when there is some particular reason for doing so, as for 

 instance something to eat, or to roost on some sand shoal or rest, 

 and not apparently because they like to be together." Lucas ^ 

 disagreed with this conclusion as follows : " I should have said that 

 gulls scattered in search of food at high water, but came together 

 sociably at other times." My own observations agree with those 

 of Lucas. These birds are usually to be seen in the company of 



> Herrick, F. H. 1909. Organization of the Gull Community. Proc. Seventh 

 International Zool. Cong., Boston, 1907, 3 pp. 



2 Mackay, G. H. Habits, of the American Herring Gull (Larus argentatus 

 smithsonianus). Auk, Vol. IX, 1892, no. 3, pp. 221-228. 



3 Lucas, F. A. Habits of the Herring Gidl. Auk, Vol. IX, no. 4, pp. 388-9. 



