180 . Strong, Habits of the Herring Gull. LApril 



was moved slowly, whereas the shining steel of the knife blade came 

 into view suddenly. 



In spite of the failure of the gulls to be disturbed by possible 

 glimpses of the man inside the tent, there is abundant evidence that 

 these birds see unusually well, as compared with most birds, in 

 weak light. As will be discussed in the section of this paper which 

 deals with the nocturnal activities of gulls, these birds are often 

 active at night. My captive gulls if very hungry will eat in con- 

 siderable darkness when their food is placed in a customary position, 

 even when it is not easy for me to make out more than the bare 

 outlines of the pieces of food. Thus on May 3, 1913, I fed my 

 gulls at about 8 P. M. The sky was clouded, and there was barely 

 enough light to follow the movements of the birds from a position 

 about fifteen feet away. The birds, which were thoroughly hungry, 

 moved about somewhat uncertainly but they fed promptly from the 

 two dishes in which their food was placed. When these birds were 

 still partly in the nestling down plumage, on the evening of July 8, 

 1911, I made some notes on their movements at night. There 

 was some light from the moon which was at half phase. I found 

 the birds swimming or standing at the edge of the water in their 

 enclosure, and they seemed to move easily in the semi-darkness. 



During even the darker portion of the night that I spent on 

 Middle Strawberry Island, I had plenty of auditory evidence 

 that both adult and young gulls were more or less active when it 

 was too dark for me to see anything of the birds. The moon set 

 about 1 : 00 A. m., and there was no light except that furnished by 

 the stars. Adult birds were evidently flying occasionally, and juve- 

 nals were occasionally heard peeping. 



On many occasions, food has been brought to my captive gulls 

 in paper wrappers. Often the package has been placed on the 

 ground more or less completely open. When the paper is flapped 

 by wind, the gulls show a good deal of apprehension. At one time 

 they would not approach the package, although they could see that 

 food was inside. They have become more accustomed to the 

 flapping paper but have not entirely lost their fear of it. This 

 experiment has been attempted only occasionally. 



Even when there has been no flapping paper, great distrust has 

 been shown for the package, when the contents were covered by 



