n. 
SIXTH WEEK. April 7 through April IS. 
Rather a good week. Weather "better. Gulls progressing. 
The first egg was discovered on April 12. 
References. 
" Attack Call 0 . Used on ground (M. April 13, 16). 
Upward. Preparatory to attack (M. April 13, 16).(M. April 12, 
4). During fierce dispute (M. April 13, 22). Immediately after 
""blunted" attack (very aggressive?) (M. April 13, 22). Alternating 
with Choking during "boundary dispute (M. April 13, 27). 
Definitely directed at a flying bird (M. April 13, 26). 
Forward . Very often mates F at one another during disputes 
with neighbors, or intruders, for instance (M. April 13, 13). It 
is very common before an advance or an actual attack, for 
instance (M. April 12, 2-3; M. April 13, 20). 
Relaxed bird (Semi E ?) attacks intruder who has been in 
lengthy F (M. April 13,19). 
Head away from opponent (M. April 9, 4). 
Female in F longer than male (M» April 11 , 4 ) . 
Mutual Display , Getting less elaborate this week. Very often 
only the E is seen. 
# 
Erect. Adopted by birds before fleeing, (M. April 13, 15-16). 
Extreme, thin neck, E adopted by bird who has been attacked (M. 
A.£fil 13, 19). Bird, advancing in "alarm" E, eventually driven 
Adopted by birds before attacking, (M. April 9, 2). Attack 
"aggressive" E at bird who does hot display, but flees immediately 
(M. April 13, 10-18-19). . .... ,,, 
"Showing nape" in E still common, for instance (M. April 13, 
4 1G ^Tail raised above wing is not uncommon, several discussions 
(M. April 12, 5; M. April 13, 21). 
Head-flagging. By partners, after U and F at flying birds 
(M. April 11 , 4 rr 
Pecking at ground . Following semi-aerial fight (M. April 9, 
4). From ll? during Mutual (M. April 11, 4). After Choking (M. 
April 11, 6). 
Choking . Description, and discussion, of Choking Call. 
Comparison with the male’s feeding call (M# April IS* 13-14-l3~^u-*io ) # 
