V 
Ludvig, J, P . 12 
Ipsi- ' ' X 
Be havio r; 
Af& g-essive behavior ; Fighting, per se, is rare. This may be 
because territories are established. Actual contact was seen to occur 
only 5 times and each tine the contact ended the aggressive behavior 
of both participants. In one case both birds immediately left the 
roostj once one bird left; and the third tine both birds moved to a 
new place on the roost. 
I was able to distinguish 2 forms of hostile display. In the 
first case Boobies close together and already on the roost extend 
necks towards one another (sometimes only one bird does): if both 
birds extend necks the display ends after a short time with no contact. 
However, if one bird does not answer the threat by extending and facing, 
the other occasionally moves to attack. In all cases seen if the de¬ 
fending bird responds, this is enough to forstall or eliminate the 
incipient attack. Usually there is no voice. A second display is 
the Head-up-wings-lifted-tail-cocked display: Shis display is directed 
towards two classes of birds, a) Flying birds coming low over the roost 
showing signs of intending to land. Voice^is a medium pitched reedy 
gurgle. It is directed towards the inflight bird and voice gets 1 cruder, 
wings raised more as the bird nears the roost (17 occasions). 1/hen 
I •* 
\ 
given, the inflight bird always flow by the roost to cam back later to 
f 
try to land, often to be "warned away" several more timesj b) towards 
birds already on the roost- voice- similar reedy gurgle, but lower pitched 
